Just like boats, airplanes, or other forms of transporation there are going to be some spacecraft that are general purpose and others that are drastically optimized for a specific task.

General Ship Types

Yes, the line between general ship types and specialized ship types is a bit fuzzy. I did the best I could.


The traveling-public gripes at the lack of direct Earth-to-Moon service, but it takes three types of rocket ships and two space-station changes to make a fiddling quarter-million-mile jump for a good reason: Money. The Commerce Commission has set the charges for the present three-stage lift from here to the Moon at thirty dollars a pound. Would direct service be cheaper?

A ship designed to blast off from Earth, make an airless landing on the Moon, return and make an atmosphere landing, would be so cluttered up with heavy special equipment used only once in the trip that it could not show a profit at a thousand dollars a pound! Imagine combining a ferry boat, a subway train, and an express elevator.

So Trans-Lunar uses rockets braced for catapulting, and winged for landing on return to Earth to make the terrific lift from Earth to our satellite station Supra-New York.

The long middle lap, from there to where Space Terminal circles the Moon, calls for comfort—but no landing gear. The Flying Dutchman and the Philip Nolan never land; they were even assembled in space, and they resemble winged rockets like the Skysprite and the Firefly as little as a Pullman train resembles a parachute.

The Moonbat and the Gremlin are good only for the jump from Space Terminal down to Luna . . . no wings, cocoon-like acceleration-and-crash hammocks, fractional controls on their enormous jets.

From SPACE JOCKEY by Robert Heinlein (1947)

The British Interplanetary Society (BIS) in general, and Sir Arthur C. Clarke in particular figured that there were three main types of spacecraft needed for the exploration of space: Space Ferry, Orbit-to-Orbit, and Airless Lander. Each is optimized for their own particular area of use.

More recently, orbital propellant depots and their related tanker ships also seem like a good piece of infrastructure. There are some sample realistic designs here, here, here, here and here. Not to mention here and here.

However, space warships are an entirely different kettle of fish.

More facetiously:


Warfare in the densely-populated Gilgamesh Cluster is almost incessant, and befitting their way of life. Gilgamite civilization has developed inexpensive and highly efficient spaceships. Vector One ships convey materials from planetary surfaces to orbit. Vector Two ships transport material between planets of a stellar system. And Vector Three ships range through the interstellar lanes.

Vector Three ships, comprising a central cylinder and detachable cargo and cabin pods, are more than simple transports, however. When war threatens, the merchant marine is recalled, the cargo pods are removed, and weapon pods are installed. Within months, an interstellar fleet can be converted from merchant-men to men-of-war.

(ed note:
Vector One ships travel in one dimension: the altitude from the planetary surface.
Vector Two ships travel in two dimensions: the two dimensional plane of the stellar system's ecliptic.
Vector Three ships travel in three dimensions: the three dimensional volume of interstellar space.)
From VECTOR 3 tabletop wargame by Greg Costikyan (1979)

“Since the days of Charan Rashuri, commander of Pride of Earth, it has been the ship commander’s obligation to recognize a moment of transition for those among his crew new to the Survey branch,” Neale began.

“I have no doubt that some among you have invested the outcrossing with far more meaning than it deserves. It is an occasion for the exchange of theater insignia. You give up the blue Orbital or yellow System ellipse you now wear. You receive the black Intersystem ellipse. But the difference in color is meaningless in itself.”

Then why do you vets call us lessers? Thackery wondered, fingering his own System insignia absently.

“Contrary to what many of you believe, this is not a promotion. The Service does not honor you by doing this. All we do here today is to mark the beginning of an opportunity for honor—honor you will have to bring to yourself in the months and years ahead. You wear the black ellipse, but you have not yet earned it.”

From ENIGMA by Michael Kube-McDowell (1986)

Type: Space Ferry

The space ferry concept is what evolved into the NASA space shuttle. Its function is to boost payload into orbit, though you can think of it as an "atmospheric lander." Refer to the section on Surface To Orbit.

These are sometimes called "interface vehicles" because their function is to transport payload through the interface boundary between Terra's atmosphere and airless space. In H. Beam Piper's scifi novels he calls them "cargo lighters", after the pre-1960s flat-bottomed barges used to transfer goods and passengers to and from moored seagoing ships.

The idea was to re-use as much of the rocket as possible, which is why the classic Collier Ferry Rocket's third stage has wings and the lower stages had drag skirts (About two decades after I wrote the prior sentence SpaceX put grid fins on the lower stage of their reusable launch vehicles, for the same reason).

In Robert Heinlein's Space Cadet, the rocket is launched from a rocket sled going up the side of Pike's Peak. Nuclear powered rockets could boost more massive payloads were it not for NIMBY, but a space elevator could boost so much more cheaply and efficiently.

Hop Davis estimates that space ferries launching from Terra will require a delta-V budget of around 10 kilometers per second (with orbital propellant depot) and require a thick atmosphere for aerobraking. It will require a bit more if there is no orbital depot, but not much more because coming down it uses aerobraking instead of propellant. The delta-V budget means they will probably have to be multi-stage if they are chemical rockets (good luck getting permission to use nuclear rockets). They will require a propulsion system with a thrust-to-weight ratio above 1.0.

Type: Orbit-to-Orbit

Orbit-to-orbit spacecraft never land on any planet, moon, or asteroid.

Therefore they are free to use efficient propulsion systems with a thrust-to-weight ratio below 1.0, such as ion drives or VASIMR. They require no landing gear or parachutes. If there ain't no landing gear, it is an orbit-to-orbit. No streamlining is required either. They require no ablative heat shields unless they are designed to perform aerobraking to burn off delta-V without requiring propellant (like the Leonov in the movie 2010 The Year We Make Contact).

Hop Davis estimates that a orbit-to-orbit spacecraft will require a delta-V budget of only 3 to 4 kilometers per second, if orbital propellant depot are available. Otherwise it will be twice that, with along with a dramatic reduction in payload capacity. 4 km/s is well within the capabilities of a chemical rocket, but any higher and you will probably need staging or a propulsion system with more exhaust velocity.

The old image of orbit-to-orbit ships look like dumb-bells, the front ball is the cargo and habitat module, the rear is the propellant and radioactive atomic drive. The stick in between is a way to substitute distance for lead radiation shielding.

The Basic Solid Core NTR or Reusable Nuclear Shuttle would make admirable backbones for an orbit-to-orbit spacecraft. Liquid hydrogen propellant and fissionables for fuel.


A ferry service of chemically-fuelled rockets linked the station to the planet beneath, for by law no atomic drive unit was allowed to operate within a thousand kilometres of the Earth’s surface. Even this safety margin was felt by many to be inadequate, for the radioactive blast of a nuclear propulsion unit could cover that distance in less than a minute.

(ed note: this implies an exhaust velocity of about 16,000 meters per second. This could be done by a liquid or gas core nuclear thermal rocket with molecular hydrogen propellant, or a solid-core nuclear thermal rocket using atomic hydrogen as propellant.)

And the third, of course, was the Ares, almost dazzling in the splendour of her new aluminium paint.

Gibson had never become reconciled to the loss of the sleek, steamlined spaceships which had been the dream of the early twentieth century. The glittering dumb-bell hanging against the stars was not his idea of a space-liner; though the world had accepted it, he had not. Of course, he knew the familiar arguments——there was no need for streamlining in a ship that never entered an atmosphere, and therefore the design was dictated purely by structural and power-plant considerations. Since the violently radioactive drive-unit had to be as far away from the crew quarters as possible, the double-sphere and long connecting tube was the simplest solution.

It was also, Gibson thought, the ugliest; but that hardly mattered since the Ares would spend practically all her life in deep space where the only spectators were the stars. Presumably she was already fuelled and merely waiting for the precisely calculated moment when her motors would burst into life, and she would pull away out of the orbit in which she was circling and had hitherto spent all her existence, to swing into the long hyperbola that led to Mars.

(ed note: the Ares can travel from Terra to Mars in three months flat.)

“Five seconds, four, three, two, one”

Very gently, something took hold of Gibson and slid him down the curving side of the porthole-studded wall on to what had suddenly become the floor. It was hard to realise that up and down had returned once more, harder still to connect their reappearance with that distant, attenuated thunder that had broken in upon the silence of the ship. Far away in the second sphere that was the other half of the Ares, in that mysterious, forbidden world of dying atoms and automatic machines which no man could ever enter and live, the forces that powered the stars themselves were being unleashed. Yet there was none of that sense of mounting, pitiless acceleration that always accompanies the take-off of a chemically propelled rocket.

The Ares had unlimited space in which to manoeuvre; she could take as long as she pleased to break free from her present orbit and crawl slowly out into the transfer hyperbola that would lead her to Mars. In any case, the utmost power of the atomic drive could move her two-thousand-ton mass with an acceleration of only a tenth of a gravity; at the moment it was throttled back to less than half of this small value.

(ed note: implies thrust of 1.962×106 Newtons, about 2 megaNewtons)

When Space Station One had vanished completely, Gibson went round to the day side of the ship to take some photographs of the receding Earth. It was a huge, thin crescent when he first saw it, far too large for the eye to take in at a single glance. As he watched, he could see that it was slowly waxing, for the Ares must make at least one more circuit before she could break away and spiral out towards Mars.

Gibson was still watching at the observation post when, more than an hour later, the Ares finally reached escape velocity and was free from Earth. There was no way of telling that this moment had come and passed, for Earth still dominated the sky and the motors still maintained their muffled, distant thunder. Another ten hours of continuous operation would be needed before they had completed their task and could be closed down for the rest of the voyage.

(ed note: one-half of a tenth of a gravity of acceleration is 0.4905 m/s2
One hour is 3,600 seconds.
0.4905×3,600 = 1,765 m/s, which is about Low Earth Orbit escape velocity of 1,800 m/s.
1+10 hours = 39,600 seconds.
0.4905×39,600 = 19,423 m/s, which is very short of solar escape velocity of 525,000 m/s
but which is impressively larger than the Terra-Mars Hohmann delta V of 5,590 m/s.
Terra-Mars Hohmann takes about 8 months, 26,000 m/s will get you to Mars in 1 month, so I guess 19,423 m/s getting you to Mars in three months sounds reasonable.
Delta V of 19,423 m/s and exhaust velocity of 16,000 m/s implies a mass ratio of 3.4, which is large but not unreasonable.
Keeping in mind that more delta V will be required for Mars capture.)

It was impossible to believe that the Ares was now racing out from the Earth’s orbit at a speed so great that even the Sun could never hold her back.

As the ship was spherical, it had been divided into zones of latitude like the Earth. The resulting nomenclature was very useful, since it at once gave a mental picture of the liner’s geography. To go “North” meant that one was heading for the control cabin and the crew’s quarters. A trip to the Equator suggested that one was visiting either the great dining-hall occupying most of the central plane of the ship, or the observation gallery which completely encircled the liner. The Southern hemisphere was almost entirely fuel tank, with a few storage holds and miscellaneous machinery. Now that the Ares was no longer using her motors, she had been swung round in space so that the Northern Hemisphere was in perpetual sunlight and the “uninhabited” Southern one in darkness. At the South Pole itself was a small metal door bearing a set of impressive official seals and the notice: “To be Opened only under the Express Orders of the Captain or his Deputy.” Behind it lay the long, narrow tube connecting the main body of the ship with the smaller sphere, a hundred metres away, which held the power plant and drive units. Gibson wondered what was the point of having a door at all if no one could ever go through it; then he remembered that there must be some provision to enable the servicing robots of the Atomic Energy Commission to reach their work.

Strangely enough, Gibson received one of his strongest impressions not from the scientific and technical wonders of the ship, which he had expected to see in any case, but from the empty passenger quarters — a honeycomb of closely packed cells that occupied most of the North Temperate Zone.

From THE SANDS OF MARS by Sir Arthur C. Clarke (1951)

The hold was a large hemispherical room with a thick central column which carried the controls and cabling to the other half of the dumb-bell-shaped spaceship a hundred metres away. It was packed with crates and boxes arranged in a surrealistic three-dimensional array that made very few concessions to gravity.

Anything more unlike the early-twentieth-century idea of a spaceship than the Star Queen would be hard to imagine. She consisted of two spheres, one fifty and the other twenty metres in diameter, joined by a cylinder about a hundred metres long. The whole structure looked like a matchstick-and-plasticine model of a hydrogen atom. Crew, cargo and controls were in the larger sphere, while the smaller one held the atomic motors and was — to put it mildly — out of bounds to living matter.

The Star Queen had been built in space and could never have lifted herself even from the surface of the Moon. Under full power her ion drive could produce an acceleration of a twentieth of a gravity, which in an hour would give her all the velocity she needed to change from a satellite of the Earth to one of Venus.

Hauling cargo up from the planets was the job of the powerful little chemical rockets. In a month the tugs would be climbing up from Venus to meet her

From "BREAKING STRAIN" by Arthur C. Clarke (1949)

Space travel had never been inexpensive, but early in the century an economic watershed had been crossed, like a saddle in low hills that nevertheless marks a continental divide. Nuclear technology moved into its most appropriate sphere, outer space; the principles were sufficiently simple and the techniques sufficiently easy to master that private companies could afford to enter the interplanetary shipping market. With the shippers came the yards, the drydocks, the outfitters.

The Falaron shipyards, one of the originals, orbited Earth two hundred and fifty miles up. Presently the only vessel in the yards was an old atomic freighter, getting an overhaul and a face lift—a new reactor core, new main engine nozzles, refurbished life-support systems, new paint inside and out. When all the work was done the ship was to be recommissioned and given a new, rather grand, name: Star Queen.

The huge atomic engines had been mounted and tested. Spacesuited workers wielding plasma torches were fitting new holds, big cylinders that fastened to the thin central shaft of the ship below the spherical crew module.

Star Queen, though of a standard freighter design, was a spacecraft quite unlike anything that had been imagined at the dawn of modern rocketry—which is to say it looked nothing like an artillery shell with fins or the hood ornament of a gasoline-burning automobile. The basic configuration was two clusters of spheres and cylinders separated from each other by a cylindrical strut a hundred meters long. The whole thing somewhat resembled a Tinkertoy model of a simple molecule. The forward cluster included the crew module, a sphere over five meters in diameter. A hemispherical cage of superconducting wires looped over the crew module, partially shielding the crew against cosmic rays and other charged particles in the interplanetary medium—which included the exhaust of other atomic ships. Snugged against the crew module's base were the four cylindrical holds, each seven meters across and twenty meters long, grouped around the central strut. Like the sea-land cargo containers of the previous century, the holds were detachable and could be parked in orbit or picked up as needed; each was attached to Star Queen's central shaft by its own airlock and was also accessible through outside pressure hatches. Each hold was divided into compartments which could be pressurized or left in vacuum, depending on the nature of the cargo.

At the other end of the ship's central strut were bulbous tanks of liquid hydrogen, surrounding the bulky cylinder of the atomic motor's reactor core. Despite massive radiation shielding, the aft of the ship was not a place for casual visits by living creatures—robot systems did what work needed to be done there.

For all its ad hoc practicality. Star Queen had an air of elegance, the elegance of form following function. Apart from the occasional horn of a maneuvering rocket or the spike or dish of a communications antenna, the shapes from which she had been assem­bled shared a geometric purity, and all alike shone dazzling white under their fresh coats of electro-bonded paint.

Two days later heavy tugs moved Star Queen into launch orbit, beyond the Van Allen belts. The atomic motor erupted in a stream of white light. Under steady acceleration the ship began a five-week hyperbolic dive toward Venus.

Still, things might have been worse. Star Queen was fourteen days into her trajectory and had twenty-one days still to go to reach Port Hesperus. Thanks to her upgraded engines she was travelling much faster than the slow freighters, the tramp steamers of the space-ways who were restricted to Hohmann ellipses, those long tangential flight paths that expended minimum energy by just kissing the orbits of Earth and Venus on opposite sides of the sun. Passenger ships equipped with even more powerful gaseous-core reactors, or fast cutters using the still-new fusion drives, could slice across from planet to planet in as little as a fortnight (2 weeks), given favorable planetary alignments—and given a profit margin that allowed them to spend an order of magnitude more on fuel—but Star Queen was stuck in the middle of the equation. Her optimal acceleration and deceleration determined both her launch window and her time of arrival.

Type: Airless Lander

These are designed for landing on bodies that have no atmosphere, but you probably could get away with using them on Mars. They evolved into NASA's Apollo Lunar Module. So they will require some sort of landing gear. But no streamlining. They will require a propulsion system with a thrust-to-weight ratio near 1.0, depending on the surface gravity of the bodies they are designed to land on. This probably means chemical propulsion, maybe a solid-core NTR. Hop Davis estimates that airless lander spacecraft will require a delta-V budget of around 5 kilometers per second if orbital and surface propellant depots are available. Otherwise it will be twice that, with along with a dramatic reduction in payload capacity.

For sample designs, go to the Lander page.

Type: Shuttlecraft

So the smart way to design is to use an orbit-to-orbit spacecraft to travel between planets, and at a planetary destination use locally based surface-to-orbit services: either a space ferry, airless lander or surface-to-orbit installation at a spaceport.

But what if there are no locally available surface-to-orbit services? If NASA dispatches a Mars mission, there ain't no Martian space shuttles to ferry the crew down to the surface.

Making the entire spacecraft land-able is often a bad idea. For one, optimizing a spacecraft for both orbit-to-orbit and surface-to-orbit operations will probably result in an inefficient ship with the disadvantages of both and the advantages of neither. If you are designing with a weak propulsion system, it might not even be possible. And even if your propulsion system is up to the task, often it is better to park your ticket home in orbit where it is safe while other means are used to send crew into a possibly dangerous situation.

The standard solution is for the main spacecraft to carry small auxiliary spacecraft as landers, either aerodynamic space ferries or airless landers. The popular term from Star Trek is "Shuttlecraft".

A large space ferry shuttlescraft on modestly sized orbit-to-orbit spacecraft can make the ship look like an arrow.

The traveling-public gripes at the lack of direct Earth-to-Moon service, but it takes three types of rocket ships and two space-station changes to make a fiddling quarter-million-mile jump for a good reason: Money.

The Commerce Commission has set the charges for the present three-stage lift from here to the Moon at thirty dollars a pound. Would direct service be cheaper? A ship designed to blast off from Earth, make an airless landing on the Moon, return and make an atmosphere landing, would be so cluttered up with heavy special equipment used only once in the trip that it could not show a profit at a thousand dollars a pound! Imagine combining a ferry boat, a subway train, and an express elevator. So Trans-Lunar uses rockets braced for catapulting, and winged for landing on return to Earth to make the terrific lift from Earth to our satellite station Supra-New York. The long middle lap, from there to where Space Terminal circles the Moon, calls for comfort-but no landing gear. The Flying Dutchman and the Philip Nolan never land; they were even assembled in space, and they resemble winged rockets like the Skysprite and the Firefly as little as a Pullman train resembles a parachute.

The Moonbat and the Gremlin are good only for the jump from Space Terminal down to Luna . . . no wings, cocoon-like acceleration-and-crash hammocks, fractional controls on their enormous jets.

From SPACE JOCKEY by Robert Heinlein (1947)

Type: Tanker

Many aerospace engineers have pointed out that all of these spacecraft can be far more cheap and efficient if there were orbital depots of propellant and/or fuel established in various strategic locations where space travel is desired. This will necessitate some sort of tanker-type spacecraft to keep the depots supplied. They will be a species of orbit-to-orbit spacecraft optimized to carry huge amounts of propellant, and hopefully be unmanned drones or robot controlled. They can use an efficient propulsion system with thrust-to-weight ration below 1.0, ion or VASIMR. Like standard orbit-to-orbit, probably a delta-V budget of 4 km/sec, unless they are in a real hurry.

There will also be a species of airless lander optimized to carry propellant to planetary based depots, this is called a "lighter". As all landers the propulsion thrust to weight ratio will have to be near 1.0, probably chemical propulsion. As standard airless lander, probably a delta-V budget of 5 km/sec. The lighter will probably be designed to land a single modular tank from the cluster carried by the tanker.

Examples of tankers include Dr. Parkinson's Lighter and Tanker, Kuck Mosquitos, Zuppero Water Ships, and Zuppero Lunar Water Trucks.

Type: Tug

Space Taxis, Space Pods, and Space Tugs are covered in the Spacesuit section.

Type: Cargo Ship

(ed note: The Cargo ship section is quite long, click the Hide button if you want to skip over this section)

If spacecraft actually lands on a planet it may be a belly-lander instead of a tail-sitter, for ease of cargo loading/unloading. Otherwise it is like unloading cargo from the 25th floor window of a skyscraper.

Conventional cargo spacecraft have a conventional ship arrangement: a rocket engine aft of a cargo hold. You know, like pretty much every rocket you've ever seen: engines on the bottom.

The hold is an enclosed area to store cargo in, sections of which may or may not be pressurized. Unpressurized sections are for cheaper storage of inert durable cargo, e.g., raw ore. Pressurized sections are more expensive storage for delicate cargo that can be easily ruined by temperature and pressure extremes, e.g., produce and live animals.

The cargo hold may be rigged with attachment points for cargo containers. The hatches may be such to allow accessing individual containers. Alternatively the hold might be basically a huge tank. This is used for bulk cargo: liquids, gases, asteroid ore dust or gravel, grain, etc.

Cargo spacecraft might not bother with an enclosed area at all. Instead cargo containers are carried on the outside of spacecraft, attached to the ship's spine.

Unconventional cargo spacecraft have the rocket engine before the cargo hold. The engines are on the top.

This uses a waterskiing arrangement, with the engine and everything acting like a waterbound motorboat, dragging the cargo behind like a water skier. The rocket exhaust is angled such that it doesn't incinerate the cargo (but angled just barely enough to minimize thrust cosine loss). If the spacecraft carries relatively few cargo cans it is a Space Truck. If it carries long strings of cargo cans it is a Space Train. Yes, the boundary between a truck and a train is totally arbitrary.

Conventional cargo spacecraft may or may not be capable of landing on a planet (airless or with atmosphere). If the cargo ship cannot land and the local infrastructure is primitive, the cargo ship may have to carry landing shuttles to ferry cargo to and from the surface. If the local infrastructure is advanced, the ship can rent shuttle services from the local spaceport.

Unconventional cargo spacecraft are highly unlikely to be capable of landing at all. Certainly not if the planet has an atmosphere.


      The Bluegrass Cat was a modular container hauler, a design that had barely changed in 50 years – a control deck and living quarters at the top and a fusion candle at the tail, connected by a long shaft, which mounted dozens of cargo pods, some of them rotating slowly around the ship’s axis. She was long, thin and ugly: a freight train in space.

     (apparently some of the cargo requires gravity. In my nomenclature, space freight trains have their engines on the front, not the rear. But nobody listens to me {wink}.).

     Her cargo to Zhuxing, the Chinese colony world orbiting Zeta Doradus, had been precision tools manufactured only on Earth, and she was departing with a load of Zhuxing’s native version of blue-green algae. This particular species was neither blue-green nor algae, but the microbes, reddish under a microscope, played a similar ecological role. They were one of the most efficient natural photosynthesizers yet discovered, and, without them, Zhuxing would have been an uninhabitable wet rock. They would fetch a high dollar on some of the colony worlds where oxygen was wanting.

     On this run the Cat carried a second cargo, two bored American intelligence officers who had spent the last sixteen days monitoring government communications on Zhuxing while the ship sat moored at an orbital freight terminal.

     The Cat’s American owners, sympathetic to Washington’s interests, provided free, no-questions-asked transit to government agents on some of its vessels. It was a secret arrangement, and a good one for both sides; U.S. intelligence agencies could quietly move around their people to foreign planets without setting up cumbersome front companies or relying on passenger liners, and the shipping line found itself deliciously free of certain regulatory pressures that its competitors faced.

From THROUGH STRUGGLE, THE STARS by John Lumpkin (2011)

Cargo Containers

For transporting huge amounts of cargo, a safe bet is that the space industries will settle on a standard cargo container size. Because in the real world this lead to the miracle of Containerization. Which transformed global trade and built, nay even changed the world.

They would allow standardized design of cargo holds, they work well with space trucks and space trains, heck they work well as inert cargo vessels. Surface to Orbit services would probably be optimized to accommodate standard cargo container form factors.

Each of the eight corners contains a twistlock to bolt them to the cargo bay floor or for stacking. Shipping containers for valuable cargo often include burglar alarms.

Standarized cargo containers would become ubiquitous and cheap enough to find secondary markets for just the empty containers.

In the real world there are DIY people who alter shipping containers into inexpensive houses. In a RocketPunk future such containers can be tansformed into crude habitat modules by adding a few incidentals (plugging leaks, a bare bones life-support system, an airlock). Add some engines and you have a scratch-built spacecraft. Ikea in Space will probably offer inexpensive habitat modules based on shipping containers.

A new interstellar space colony on a shirt-sleeve habitable planet might bring along a commercial Farm From A Box to jump-start their agricultural self-sufficiency. Everything you need for a quick farm, neatly packed inside a shipping container. It's a kit!

Other "kits" mounted inside shipping containers include water treatment plants and electrical power generators. The military has shipping container kits containing medical surgery theaters, command and control facilities, and missile launchers.

And science fiction authors looking for an interesting (comments) background situation for their novel can pick up a few hints by doing a web search for news containing the search term "cargo container."

Eric Tolle was of the opinion that hexagonal cargo containers would probably be for bulk dry goods, Liquids would would best in cylinders or spheres, and containerized shipping would be best in rectangular cargo pods.



An intermodal container is a large standardized shipping container, designed and built for intermodal freight transport, meaning these containers can be used across different modes of transport – from ship to rail to truck – without unloading and reloading their cargo. Intermodal containers are primarily used to store and transport materials and products efficiently and securely in the global containerized intermodal freight transport system, but smaller numbers are in regional use as well. These containers are known under a number of names, such as simply container, cargo or freight container, ISO container, shipping, sea or ocean container, sea van or (Conex) box, sea can or c can.

Intermodal containers exist in many types and a number of standardized sizes, but ninety percent of the global container fleet are so-called "dry freight" or "general purpose" containers, durable closed steel boxes, mostly of either twenty or forty feet (6.1 or 12.2 m) standard length. The common heights are 8 feet 6 inches (2.6 m) and 9 feet 6 inches (2.9 m) – the latter are known as High Cube or Hi-Cube containers.

Just like cardboard boxes and pallets, these containers are a means to bundle cargo and goods into larger, unitized loads, that can be easily handled, moved, and stacked, and that will pack tightly in a ship or yard. Intermodal containers share a number of key construction features to withstand the stresses of intermodal shipping, to facilitate their handling and to allow stacking, as well as being identifiable through their individual, unique ISO 6346 reporting mark.

In 2012, there were about 20.5 million intermodal containers in the world of varying types to suit different cargoes. Containers have largely supplanted the traditional break bulk cargo – in 2010 containers accounted for 60% of the world's seaborne trade. The predominant alternative methods of transport carry bulk cargo – whether gaseous, liquid or solid – e.g. by bulk carrier or tank ship, tank car or truck. For air freight, the lighter weight IATA-defined unit load device is used.

Ninety percent of the global container fleet consists of "dry freight" or "general purpose" containers – both of standard and special sizes. And although lengths of containers vary from 8 to 56 feet (2.4 to 17.1 m), according to two 2012 container census reports about 80% of the world's containers are either twenty or forty foot standard length boxes of the dry freight design. These typical containers are rectangular, closed box models, with doors fitted at one end, and made of corrugated weathering steel (commonly known as CorTen) with a plywood floor. Although corrugating the sheet metal used for the sides and roof contributes significantly to the container's rigidity and stacking strength, just like in corrugated iron or in cardboard boxes, the corrugated sides cause aerodynamic drag, and up to 10% fuel economy loss in road or rail transport, compared to smooth-sided vans.

Standard containers are 8-foot (2.44 m) wide by 8 ft 6 in (2.59 m) high, although the taller "High Cube" or "hi-cube" units measuring 9 feet 6 inches (2.90 m) have become very common in recent years. By the end of 2013, high-cube 40 ft containers represented almost 50% of the world's maritime container fleet, according to Drewry's Container Census report.

About 90% of the world's containers are either nominal 20-foot (6.1 m) or 40-foot (12.2 m) long, although the United States and Canada also use longer units of 45 ft (13.7 m), 48 ft (14.6 m) and 53 ft (16.15 m). ISO containers have castings with openings for twistlock fasteners at each of the eight corners, to allow gripping the box from above, below, or the side, and they can be stacked up to ten units high. Regional intermodal containers, such as European and U.S. domestic units however, are mainly transported by road and rail, and can frequently only be stacked up to three laden units high. Although the two ends are quite rigid, containers flex somewhat during transport.

Container capacity is often expressed in twenty-foot equivalent units (TEU, or sometimes teu). A twenty-foot equivalent unit is a measure of containerized cargo capacity equal to one standard 20-foot (6.1 m) long container. This is an approximate measure, wherein the height of the box is not considered. For example, the 9 ft 6 in (2.9 m) tall high-cube, as well as 4-foot-3-inch half-height (1.3 m) 20-foot (6.1 m) containers are equally counted as one TEU. Similarly, extra long 45 ft (13.72 m) containers are commonly designated as two TEU, no different than standard 40 feet (12.19 m) long units. Two TEU are equivalent to one forty-foot equivalent unit (FEU).

In 2014 the global container fleet grew to a volume of 36.6 million TEU, based on Drewry Shipping Consultants' Container Census. Moreover, in 2014 for the first time in history 40-foot High cube containers accounted for the majority of boxes in service, measured in TEU.

Manufacturing prices for regular, dry freight containers are typically in the range of $1750—$2000 U.S. per CEU (container equivalent unit), and about 90% of the world's containers are made in China. The average age of the global container fleet was a little over 5 years from end 1994 to end 2009, meaning containers remain in shipping use for well over 10 years


Other than the standard, general purpose container, many variations exist for use with different cargoes. The most prominent of these are refrigerated containers (a.k.a. reefers) for perishable goods, that make up six percent of the world's shipping boxes. And tanks in a frame, for bulk liquids, account for another 0.75% of the global container fleet.

Although these variations are not of the standard type, they mostly are ISO standard containers – in fact the ISO 6346 standard classifies a broad spectrum of container types in great detail. Aside from different size options, the most important container types are:

  • General-purpose dry vans, for boxes, cartons, cases, sacks, bales, pallets, drums, etc., Special interior layouts are known, such as:
    • rolling-floor containers, for difficult-to-handle cargo
    • garmentainers, for shipping garments on hangers (GOH)
  • Ventilated containers. Essentially dry vans, but either passively or actively ventilated. For instance for organic products requiring ventilation
  • Temperature controlled – either insulated, refrigerated, and/or heated containers, for perishable goods
  • Tank containers, for liquids, gases, or powders. Frequently these are dangerous goods, and in the case of gases one shipping unit may contain multiple gas bottles
  • Bulk containers (sometimes bulktainers), either closed models with roof-lids, or hard or soft open-top units for top loading, for instance for bulk minerals. Containerized coal carriers and "bin-liners" (containers designed for the efficient road and rail transportation of rubbish from cities to recycling and dump sites) are used in Europe.
  • Open-top and open-side containers, for instance for easy loading of heavy machinery or oversize pallets. Crane systems can be used to load and unload crates without having to disassemble the container itself. Open sides are also used for ventilating hardy perishables like apples or potatoes.
  • Platform based containers such as:
    • flat-rack and bolster containers, for barrels, drums, crates, and any heavy or bulky out-of-gauge cargo, like machinery, semi-finished goods or processed timber. Empty flat-racks can either be stacked or shipped sideways in another ISO container
    • collapsible containers, ranging from flushfolding flat-racks to fully closed ISO and CSC certified units with roof and walls when erected.

Containers for Offshore use have a few different features, like pad eyes, and must meet additional strength and design requirements, standards and certification, such as the DNV2.7-1 by Det Norske Veritas and the European standard EN12079: Offshore Containers and Associated Lifting Sets.

A multitude of equipment, such as generators, has been installed in containers of different types to simplify logistics – see containerized equipment for more details.

Swap body units usually have the same bottom corner fixtures as intermodal containers, and often have folding legs under their frame so that they can be moved between trucks without using a crane. However they frequently don't have the upper corner fittings of ISO containers, and are not stackable, nor can they be lifted and handled by the usual equipment like reach-stackers or straddle-carriers. They are generally more expensive to procure.


Basic dimensions and permissible gross weights of intermodal containers are largely determined by two ISO standards:

  • ISO 668:2013 Series 1 freight containers—Classification, dimensions and ratings
  • ISO 1496-1:2013 Series 1 freight containers—Specification and testing—Part 1: General cargo containers for general purposes

Weights and dimensions of the most common standardized types of containers are given below. Values vary slightly from manufacturer to manufacturer, but must stay within the tolerances dictated by the standards. Empty weight (tare weight) is not determined by the standards, but by the container's construction, and is therefore indicative, but necessary to calculate a net load figure, by subtracting it from the maximum permitted gross weight.

20'40'40' high-cube45' high-cube48'53'
Length19 ft 10.5 in
(6.058 m)
40 ft 0 in
(12.192 m)
40 ft 0 in
(12.192 m)
45 ft 0 in
(13.716 m)
48 ft 0 in
(14.630 m)
53 ft 0 in
(16.154 m)
Width8 ft 0 in
(2.438 m)
8 ft 0 in
(2.438 m)
8 ft 0 in
(2.438 m)
8 ft 0 in
(2.438 m)
8 ft 6 in
(2.591 m)
8 ft 6 in
(2.591 m)
Height8 ft 6 in
(2.591 m)
8 ft 6 in
(2.591 m)
9 ft 6 in
(2.896 m)
9 ft 6 in
(2.896 m)
9 ft 6 in
(2.896 m)
9 ft 6 in
(2.896 m)
Length19 ft 3 in
(5.867 m)
39 ft 5 4564 in
(12.032 m)
39 ft 4 in
(11.989 m)
44 ft 4 in
(13.513 m)
47 ft 6 in
(14.478 m)
52 ft 6 in
(16.002 m)
Width7 ft 8 1932 in
(2.352 m)
7 ft 8 1932 in
(2.352 m)
7 ft 7 in
(2.311 m)
7 ft 8 1932 in
(2.352 m)
8 ft 2 in
(2.489 m)
8 ft 2 in
(2.489 m)
Height7 ft 9 5764 in
(2.385 m)
7 ft 9 5764 in
(2.385 m)
8 ft 9 in
(2.667 m)
8 ft 9 1516 in
(2.691 m)
8 ft 11 in
(2.718 m)
8 ft 11 in
(2.718 m)
Width7 ft 8 18 in
(2.340 m)
7 ft 8 18 in
(2.340 m)
7 ft 6 in
(2.286 m)
7 ft 8 18 in
(2.340 m)
8 ft 2 in
(2.489 m)
8 ft 2 in
(2.489 m)
Height7 ft 5 34 in
(2.280 m)
7 ft 5 34 in
(2.280 m)
8 ft 5 in
(2.565 m)
8 ft 5 4964 in
(2.585 m)
8 ft 10 in
(2.692 m)
8 ft 10 in
(2.692 m)
Internal volume1,169 cu ft
(33.1 m3)
2,385 cu ft
(67.5 m3)
2,660 cu ft
(75.3 m3)
3,040 cu ft
(86.1 m3)
3,454 cu ft
(97.8 m3)
3,830 cu ft
(108.5 m3)
gross weight
66,139 lb
(30,000 kg)
66,139 lb
(30,000 kg)
68,008 lb
(30,848 kg)
66,139 lb
(30,000 kg)
67,200 lb
(30,500 kg)
67,200 lb
(30,500 kg)
Empty weight4,850 lb
(2,200 kg)
8,380 lb
(3,800 kg)
8,598 lb
(3,900 kg)
10,580 lb
(4,800 kg)
10,850 lb
(4,920 kg)
11,110 lb
(5,040 kg)
Net load61,289 lb
(27,800 kg)
57,759 lb
(26,199 kg)
58,598 lb
(26,580 kg)
55,559 lb
(25,201 kg)
56,350 lb
(25,560 kg)
56,090 lb
(25,440 kg)

Reporting mark

Each container is allocated a standardized ISO 6346 reporting mark (ownership code), four letters long ending in either U, J or Z, followed by six digits and a check digit. The ownership code for intermodal containers is issued by the Bureau International des Containers (International container bureau, abbr. B.I.C.) in France, hence the name BIC-Code for the intermodal container reporting mark. So far there exist only four-letter BIC-Codes ending in "U".

The placement and registration of BIC Codes is standardized by the commissions TC104 and TC122 in the JTC1 of the ISO which are dominated by shipping companies. Shipping containers are labelled with a series of identification codes that includes the manufacturer code, the ownership code, usage classification code, UN placard for hazardous goods and reference codes for additional transport control and security.

Following the extended usage of pallet-wide containers in Europe the EU started the Intermodal Loading Unit (ILU) initiative. This showed advantages for intermodal transport of containers and swap bodies. This led to the introduction of ILU-Codes defined by the standard EN 13044 which has the same format as the earlier BIC-Codes. The International Container Office BIC agreed to only issue ownership codes ending with U, J or Z. The new allocation office of the UIRR (International Union of Combined Road-Rail Transport Companies) agreed to only issue ownership reporting marks for swap bodies ending with A, B, C, D or K – companies having a BIC-Code ending with U can allocate an ILU-Code ending with K having the same preceding letters. Since July 2011 the new ILU codes can be registered, beginning with July 2014 all intermodal ISO containers and intermodal swap bodies must have an ownership code and by July 2019 all of them must bear a standard-conforming placard.

From the Wikipedia entry for INTERMODAL CONTAINER

The standardized Cargo Containers are the heart of interstellar trade.

Containers come in many different types, each with a designation to distinguish the different types and uses. Designation for each container is (size)(type)/(tech level). There are three sizes of containers, coded as 4A (8 dtons or 112 cubic meters), 4C (4 dtons, 32 m3) or 4D (2 dtons, 16 m3). Containers are 3 meters high by 3 meters wide, and include all doors and fittings for cargo handling equipment. The size 4A containers are 12 meters long, 4C containers are 6 meters long, and 4D containers are 3 meters long.

Cargo Container Types

Container types
Type CodeNameDescription
00 General Purpose A simple box with doors at both ends.
05 Sealed Same as type 00, but capable of being sealed against external atmosphere. Does not include life support or environmental controls.
32 Controlled Environment A type 05 but including environmental controls for heat and cooling. Can maintain any temperature between -35°C and 50°C. Requires external power supply, and has a 24 hour battery power supply.
50 Open Top Same as type 00, but missing the top.
55 Open Frame An open box frame with structural cross members. Used as a frame for heavy equipment. Can be covered with a flexible covering.
67 Modular A box designed to come apart into the six sides. Can be used as a type 00, type 50, or type 55, or folded flat for shipment. Four flat containers can be shipped in the space of one assembled container.
70 Tank A type 55 with a tank for transporting liquids or gasses in bulk.
90 Habitat A modular office, building component, or habitat. Provides full life support and cramped cabin quarters. Requires external power supply for life support, and has a 24 hour battery supply.

(ed note: This is a modification to the rules for the Traveller role playing game. But the reasoning is of general interest to cargo starship designers. Costs are in Traveller "credits" or CR, more or less equivalent to $1 US)

April 2014 issue.

Why are standard cargo containers in Traveller 3m wide, 3m high and 6m long? Because no one consider the implications of containerized cargo on Earth when they wrote that description decades ago. Nor did they consider the standards for starships in Traveller. The standard cargo container, as written, is unusable in the standard starships, as written, in Classic Traveller.

A subsidized merchant (Type R) cannot stack two standard cargo containers in its hold because the deck height is only 6m. There would be no room to maneuver them about. From past experience working in steel yards and manufacturing plants, I would say as a minimum the decks would need to be 6.3m apart in order to safely stack two 3m containers, and it seems the writers of Fire, Fusion, & Steel 2 would agree because they suggest a minimum door size that is 10% larger in dimension than the corresponding dimension of anything that will be moved through it.

So let’s take a fresh look at containerized cargo for Traveller. On Earth, while there are occasionally containers dented by mishandling, it is rare, so a Traveller armor rating of 1 seems to be a reasonable ‘guesstimate’. This is also the standard minimum for grav vehicles, probably for much the same reason.

If the deck heights will be 3m then the maximum height of cargo containers should be 2.7m since starships will be the primary mode of transport. Does anyone know the Imperium’s standard axle size? Never mind, we’ll leave the other two dimensions at 3m and 6m. An Imperial standard shipping container would have a surface area of 84.6m2 and an external volume of 48.6 m3. Other important measurements depend on composition, per the table below.


Standard Cargo Container Measurements
TLMaterialVolume*Mass (kg)Cost (Cr)
0Light Wood42.5572.4171,813
4Soft Steel48.2522.785558
5Hard Steel48.3042.366592
6Titanium Alloy48.4031.5781,973
7Light Composite48.4521.0371,038
8Composite Laminate48.5010.790790
9Light Ceramic Composite48.4820.7111,067
16Collapsed CrystalIron48.5700.385651

* Internal volume available to shipper, in m3

Containers are inexpensive and finding them “repurposed” to other functions would be quite likely. Researching “container architecture” might offer some ideas.

None of these would be vacuum resistant and the TL 0 and 1 containers couldn’t be made so. Adding a cargo door (e.g. one that was proof against vacuum) would add to the cost. Since most starships maintain shirt-sleeve environments in cargo areas this usually won’t be a problem; however, for high end cargos it might be worth a shipper’s while to pop for the added protection.


Cost of Vacuum-resistant Cargo Containers
TLCost (Cr) TLCost (Cr)
33,647 86,825
44,708 96,582
54,604 107,131
65,661 127,540
76,227 167,707

A container could hold a kiloton of high density material so planetary standards bodies would probably call for a maximum gross mass. What that would be IYTU would depend on what standards exist for cargo moving equipment. Present-day ISO standards call for a maximum net load of 28.2 tonnes but present-day standard cargo containers are 21% smaller than those described here, so 38 tonnes would be comparable on a volume for volume basis.

There are probably sub-containers available as well. These would be designed to fit inside the main container with little wiggle room. They might be standardized or not IYTU. Because they are protected by the main container they would have no minimum standards and could be as simple as plastic or cardboard boxes. Standard widths would be 2.8, 1.4, 0.93, 0.7, 0.56, 0.46, 0.4, 0.35, and possibly 0.31, 0.28, 0.25, and 0.23. Standard lengths would be 5.8, 2.9, 1.93, 1.45, 1.16, 0.96, 0.82, 0.72, 0.64, 0.58, 0.52, and 0.48. Standard heights would be less likely, especially on the smaller end, but if you had them they would probably be on the order of 2.4, 1.2, 0.8, 0.6, 0.48, 0.4, 0.34, 0.3, 0.26, 0.24, 0.21, and 0.2.

Note that the widths and lengths refer to their placement within the main container. One could have sub-containers that were longer from side to side of the main container than they were front to back, relatively speaking.

Most PCs won’t know or care what’s inside the shipping containers in the hull, but if you have PCs that do something other than standard merchant type activities this information could be useful. There are actually companies that arrange sub cargos for small concerns that cannot afford to ship full containers and they make good money saving their customers money on shipping by bundling their shipments with others to form full containers.



      Pinelea orbit, 194 days out of Calissant orbit.

     'I have it, Tilli,' I radioed, as I felt the cargo crane latch on to the shipping container. A green light on the console confirmed it.
     'It's yours,' replied Tilli, releasing the container from the lighter's cargo arm, clearing the last red light. We were over the night side of Pinelea, its cities glowing jewels in the velvet darkness beneath us. Through the clearsteel dome of the raised cargo tower I could see Tilli's lighter, bright in our flood lights, hanging in space above no.1 hold. It was a standard two box lighter, a stubby, delta winged craft with wingtip rocket engines designed to ferry two 4x4x24meter shipping containers between surface and orbit. She'd pushed the container out of the lighter's rear cargo doors and it now hung at the end of the spider-like cargo crane between the lighter and the ship. I carefully drew the container away from the lighter.

     'Thanks Til. Until our orbits cross again, whenever that'll be, fair orbits.'
     'Fair orbits, Captain Litang,' the last with a laugh.
     And with that the steering rockets and the big wing rockets of Tilli's lighter flared, sending the lighter outwards in a shallow arc and plunging downwards for Pinelea and I was very much alone.

     Well, the box dangling on the end of the cargo crane wasn't going to stow itself — though it would've eleven thousand years ago, before the sentient machines went on strike and eventual exile in the inner drifts, free to do what sentient machines do. Since then the Unity Charter not only limits machine intelligence to a level well short of self-awareness but requires active human participation in every operation. So, if I wanted to clear Pinelea, I'd best see to stowing that last box.
     Using the control levers and with a neurological link to the crane's sensors via the com link I wore on my wrist, I swung the box into position and guided it into its slot in the hold — operating the crane on the macro level with the manual controls while the crane's sensors and the ship's computer did the micro level adjustments preventing me from making a hash of it.

     Containers are stored on end, locked on a movable docking bar at the bottom of the hold, which provides a sensor link and power to the boxes. Each box has its own environmental unit to keep it within the content's specified limits. I locked the box down, braced the hold's containers, lowered the crane and folded the hatch covers over the holds.

From THE BRIGHT BLACK SEA by C. Litka (2015)

Space Truckers and Trains

I am arbitrarily defining a conventional cargo ship as one with the engines in the aft section of the spacecraft, while space trucks and space trains have the engines in the fore section (like an 18-wheeler or a choo-choo train). The only difference between space trucks and space trains is the number of cargo cannisters.


As attractive as is the admirable reduction in radiation shield mass offered by the waterskiiing spacecraft concept, there are practical problems in being towed on the end of a kilometer-long cable.

But the bit about using tension instead of compression members is still a worthwhile idea. Take some species of space tug, mount the propusion system on outriggers so the exhaust does not fire directly back along the ship's spine, and attach cargo modules to massive couplings on the bottom of the thrust frame.

If the space tug is hauling one or two cargo modules, this resembles an 18-wheeler hauling a couple of semi-trailers. A "space-trucker" so to speak.

As with all cargo spacecraft, delicate cargo will be housed in pressurized temperature-controlled cannisters but bulk ores and other insensitive cargo will just be dragged along in nets.



“There it is,” Shadow Jack said, with almost a sigh. “Mecca rock.”

Betha watched it come into view at the port: a fifty-kilometer potato-shaped lump of stone, scarred by nature’s hand and man’s. Mecca’s long axis pointed to the sun; the side nearest them lay in darkness, haloed by an eternal corona of sunglare. As they closed she began to see landing lights; and, between them, immense shining protrusions lit from below, throwing their shadows out to be lost in the shadow of the void. She identified them finally as storage tanks—enormous balloons of precious gases. At last… She stirred in the narrow, dimly lit space before the instruments, felt her numbed emotions stir and come alive.

“Out there, Shadow Jack.” She leaned closer to the port, rubbed the fog of moisture from the glass. “A tanker coming in.”

He peered past her. They saw the ship, still lit by the sun: a ponderous metallic tick, its plastic belly bloated with precious gases and clutched inside three legs of steel, booms for the ship’s nuclear-electric rockets. “Look at the size of that! It must be comin’ in from the Rings. They wouldn’t use that on local hauls." He raised his head, following its downward arc. “Down there, that must be the docking field.”

She could see the field clearly now, an unnatural gleaming smoothness in the artificial/light, cluttered with cranes and ringed by more mechanical parasites, gorged and empty. Smaller craft moved above them, fireflies showing red: sluggish tows in a profusion of makeshift incongruity.

From THE OUTCASTS OF HEAVEN BELT by Joan Vinge (1978)

He glanced up, at the purity of blackness unmarred by atmosphere, at the stars. Somewhere below his feet, through kilometers of nearly solid rock, was the tiny, pale spinel of the sun Heaven. He would be seeing it again, soon enough—he focused on the looming grotesqueness tethered at the end of the mooring cable, bifurcated by the abrupt edge of the asteroid’s horizon: the converted volatile freighter that would take them across the Main Belt and on in to Heaven’s second planet, to pick up one man…and a treasure. The three jutting booms that kept its nuclear electric rockets suspended away from the living quarters clutched rigid cylinders instead of the usual flimsy volatiles sack; it carried a liquid fuel rocket for their descent to the planet’s surface.

From LEGACY by Joan Vinge (1980)

(ed note: this is a laser thermal rocket energized by powerful remote lasers on an L5 colony)

     The next item on the agenda was the laser-powered high-acceleration tug, otherwise referred to as the ultra-fast optical system, UFOS having more dash and elan than LPHAT. Corporate Susan made the presentation it had worked up with Skaskash and Lady Dark.

     "The basic idea isn't bad,” said Cantrell. “How would you keep the lens oriented normal to the laser when you start to move the engine to a different orientation?"
     "We have a pair of pipes at the equator of the sphere, pumping water in opposite directions,” said Corporate Susan. “Also, inside the sphere, under the photovoltaic surface, are two pairs of circular loops, set flush with the surface and at right angles to each other. Each pair pumps water in a counterrotary direction. The pumps are all controlled, so the UFOS is gyroscopically stabilized in three planes."

     "I see,” Dornbrock said. “How do you move the engine around on the surface of the geodesic sphere?"
     "The sphere rests on this little egg cup here,” said Corporate Susan. “The egg cup is a plastic perforated surface. When we want to move, we pressurize the surface, and the geodesic sphere floats on an air cushion. Then the mechanical hands around the perimeter of the egg cup orient the engine while the sphere stays put, or the engine stays put and the hands reorient the sphere, depending on how you work the gyroscopic pumps."
     "Wouldn't you lose a lot of air pressurizing the perforated surface?” Corporate Forziati asked.
     "No, actually,” Corporate Susan replied. “We have built a little valve into each perforation which only operates when the surface is depressed by the weight of the element of the sphere in contact with it.” A diagram flashed on her telecon screen for a moment.
     "Thank you,” Forziati said. “And when you are not under thrust, weight is no problem and you don't pressurize. Very good."

     "On the other end of the egg cup,” Bogdanovitch said, “where you have the engines and the tanks for the reaction mass, you have a long cable supporting the warship. Couldn't you have the ship on an egg cup, too?"
     "No,” Corporate Susan replied. “The engines are thrusting against the geodesic sphere, which rests on top of the egg cup. The warship must keep its center of mass in line with the axis of thrust. Put it on the sphere with its own egg cup, and it would have to stay lined up with the engines—on the other side—which means the sphere would have to be built stronger, and heavier."
     "And it would get in the way of the big laser beam,” Cantrell added.

     "Then how does the warship stay out of the jet of ions?” asked Bogdanovitch.
     "It rotates at the end of its cable,” said Corporate Susan, “and makes a little circle around the jet of uranium ions which provide the main thrust. The jet of boron and hydrogen is flared off, simply to provide electrical neutrality, but it also provides a tiny bit of thrust, which can be used to offset the wobble the ship would otherwise cause by swinging around the main jet."

     "I don't understand,” Marian said.
     Corporate Susan dissolved into a diagram. “Consider the vector diagram of the force exerted by the cable supporting the ship,” said the computer. “Most of it runs through the axis of thrust, but there is a small component going at right angles to that thrust. The boron and hydrogen, flared off with the excess electrons from the decaply ionized uranium, can be adjusted to exactly balance that small component. The flare—a very soft jet—would be in the same plane as the ship, and pointing in the same direction, to push where the ship is pulling."
     "The jet—the flare, I mean, turns with the cable?” asked Marian.
     "Of course,” said Corporate Susan.

     "Orange and green,” said Marian. “Very pretty. What color is the uranium jet?"
     "Hard X-ray,” Skaskash said. “It would probably be dangerous for two or three hundred kilometers."
     "That might be an idea whose time has come,” Cantrell said at last. “Any more questions? No? Shall we build it? ... It seems to be unanimous."

     "I have a model at the shop you can use. I'll have the changes you wanted put on, and you can use that, if you want."
     "How big is it?"
     "Not big—” Ilgen stretched his arms. “Maybe a meter and a half. Did you decide what ship you wanted with it?"
     "The Alamo. We need to impress people, and the Alamo is the biggest thing we've got."
     "Right, Charlie. I'll throw in a model of the Alamo to the same scale. The UFOS plus the Alamo figures to go seven to eight times as fast as any cruiser."
     Cantrell whistled softly.
     "I'll tell the Navy,” he said. “That ought to make them very happy."

From THE PIRATES OF ROSINANTE by Alexis Gilliland (1982)

When space westerns decide to get literal with the genre name, these guys tend to show up.

They are usually depicted as, well, southern-fried semi truckers that happen to fly cargo spaceships instead. Usually easygoing, unflappable, and have a backwoods wisdom developed during the time spent alone on long hauls between solar systems. Occasionally they're smugglers, but usually aren't drug mules. From time to time, between hauls they'll stop at a local tavern and challenge various folks to a little arm-wrestling, drinking contests and then drunken brawls. Tend to talk in a Southern or slight Texan drawl.

Overlaps occasionally with the Boisterous Bruiser, Gentle Giant, Warrior Poet or other ersatz cowboy-style archetypes.

Their ships are most likely Used Future pieces of junk, just barely held together — bonus points if they're blocky, and bear a surprising resemblance to modern Mack trucks or other 18-wheelers.

Often a subtrope of Intrepid Merchant.

(ed note: see TV Trope page for list of examples)

We had a lot of luck on Venus
We always had a ball on Mars
Meeting all the groovey people
We've rocked the Milky Way so far
We danced around with Borealis
We're space truckin' round the the stars
Come on let's go Space Truckin'

Remember when we did the moonshot
And Pony Trekker led the way
We'd move to the Canaveral moonstop
And everynaut would dance and sway
We got music in our solar system
We're space truckin' round the stars
Come on let's go Space Truckin'

The fireball that we rode was moving
But now we've got a new machine
Yeah Yeah Yeah Yeah the freaks said
Man those cats can really swing
They got music in their solar system
They've rocked around the Milky Way
They dance around the Borealis
They're Space Truckin' everyday
Come on
From SPACE TRUCKIN' by Deep Purple (1972)

      The observation bubble on the side of the Cay Habitat had a televiewer, Leo discovered to his delight, and furthermore it was unoccupied at the moment. His own quarters lacked a viewport. He slipped within. His schedule allowed this one free day to recover from trip fatigue and jump lag before his course was to begin.

     The curve of Rodeo’s horizon bisected the view from the bubble, and beyond it the vast sweep of stars. Just now one of Rodeo’s little mice moons crept across the panorama. A glint above the horizon caught Leo’s eye.

     He adjusted the televiewer for a close-up. A GalacTech shuttle was bringing up one of the giant cargo pods, refined petrochemicals or bulk plastics bound for petroleum-depleted Earth perhaps. A collection of similar pods floated in orbit. Leo counted. One, two, three … six, and the one arriving made seven. Two or three little manned pushers were already starting to bundle the pods, to be locked together and attached to one of the big orbit-breaking thruster units.

     Once grouped and attached to their thruster, the pods would be aimed toward the distant wormhole exit point that gave access to Rodeo local space. Velocity and direction imparted, the thruster would detach and return to Rodeo orbit for the next load. The unmanned pod bundle would continue on its slow, cheap way to its target, one of a long train stretching from Rodeo to the anomaly in space that was the jump point.

     Once there, the cargo pods would be captured and decelerated by a similar thruster, and positioned for the jump. Then the superjumpers would take over, cargo carriers as specially designed as the thrusters for their task. The monster cargo jumpers were hardly more than a pair of Necklin field generator rods in their protective housings so positioned as to be fitted around a constellation of pod bundles, a bracketing pair of normal space thruster arms, and a small control chamber for the jump pilot and his neurological headset. Without their balancing pod bundles attached the superjumpers reminded Leo of some exceptionally weird and attenuated long-legged insects.

     Each jump pilot, neurologically wired to his ship to navigate the wavering realities of wormhole space, made two hops a day, inbound to Rodeo with empty pod bundles and back out again with cargo, followed by a day off; two months on duty followed by a month’s unpaid but compulsory gravity leave, usually financially augmented with shuttle duties. Jumps were more wearing on pilots than null-gee was. The pilots of the fast passenger ships like the one Leo had ridden in on yesterday called the superjumper pilots puddle-jumpers and merry-go-round riders. The cargo pilots just called the passenger pilots snobs.

     Leo grinned, and considered that train of wealth gliding through space. No doubt about it, the Cay Habitat, fascinating as it was, was just the tail of the dog to the whole of GalacTech’s Rodeo operation. That single thruster-load of pods being bundled now could maintain a whole town full of stockholding widows and orphans in style for a year, and it was just one of an apparently endless string. Base production was like an inverted pyramid, those at the bottom apex supporting a broadening mountain of ten-percenters, a fact which usually gave Leo more secret pride than irritation.

From FALLING FREE by Lois McMaster Bujold (1988)


Space Truckers haul relatively small numbers of cargo modules, often attached to a framework. However if the tug is hauling a long chain of cargo modules, this is more like a freight train with a locomotive at the front and a string of freight cars in tow. A "space train" as it were.

Much like railroad locomotives, this will be less like loading crates into a seagoing container ship and more like latching cargo cans into long strings terminating at the rocket engine at the top.



This was the lead ship for the warp superconvoys, the 100-kilometer cargo carriers that revolutionized interstellar industrial transport. Configured in 8-ship linked octogons at the head of the convoy, with 4-ship squares of booster tugs after each 10-container segment, and all controls subspace-radio synchronized, these superconvoys transported billions of kilograms per superconvoy.

Length225 m
Beam220 m
Draught45.6 m
Mass72.5 million kg
Ship's Complement
Std Ship's Complement66
Range2000 light-years
Cruising SpeedEmpty - Warp 3.5
Loaded - Warp 2
EnginesAdv 3rd Gen Warp Drive
Fuel1:1 matter/antimatter
NotesTractor beam coupling for cargo containers
Most powerful thrust in starship history

SUPERCONVOYS OPEN NEW ERA OF TRADE: Billion ton ships are boon to industry (2161)

Engineering Log:

It's working! Warp effect is being engaged, and this superconvoy is rolling! Next stop—Centauri Spaceworks.

I'll let the boys upstairs take the glory, but the truth is old greasemonkey Sabella down here in the Engine Room is who straightened this whole mess out, I must admit in all humility.

Problem: how to transport raw materials from whistle-stop asteroid belts in the boondock sectors to the space factories of the UFP? And I'm not talking a freighter or two here. I'm talking about the billions and billions of metric tonnage needed each stardate to feed the Federation's ravening industrial plant. Star Fleet is stymied.

Solution: Sabella to the rescue. lt's elementary, I patiently explain, what we need are warp convoys of a hundred freighters and more. It can't be done, sneer the design baboons. No ship could produce a warp effect that great. Who said anything about one ship? I reply.

So I spelled it out for them. At the head of the convoy, assemble a configuration of heavy warp-drive tugs, say eight of them in an octagon. Lock their controls together and use the whole pile as the inertial driver. Next, string out a dozen or so of those new kilometer-long cargo cans, coupling them with tractor beams. Then—and here my brilliance staggers even my own modest self—plug in another configuration of warp tugs, four should do it, and knit the rest of the convoy with the same pattern, synchronize it all with subspace radio so that all warp engines engage simultaneously, and ride into the sky!

It can't be done, cry the designers.

An interesting conjecture, muses star Fleet.

It can be done, admit the designers in wonderment. Maybe only warp 2 or so, but this would save years of travel time, and trillions of credits.

Trillions? asks Star Fleet. Maybe we'll consider it. They considered it, they did it, it's done.

Merely brilliant, Sabella, I say. Merely brilliant.


Admiral's Log:

Our flagship Endurance has run a final sensor scan of Bayard’s Planet, and I can report with certainty that not a single inhabitant has been missed by this, the largest spacelift in history. None too soon either. The shock wave from the supernova explosion that destroyed the Kepler will reach this systems sun in less than three star-dates, and it is 100 percent probable that it will initiate a chain reaction nova.

And the nova will destroy all life in the star system. All oceans will boil away; the gamma ray bombardment will scorch the surface; the planet itself may undergo an internal disruption and blow apart. it was imperative that Bayard’s Planet be evacuated. But how to evacuate ten million inhabitants? With the biggest spacelift ever.

Every starship within a fifty light-year radius was pressed into the effort by special request of the UFP. And I am just amazed by the response. Cruisers, destroyers, scout-ships, corvettes, all rendezvoused. Also trading clippers, low-warp tugs, even pleasure crafts of every type all rallied to the cause.

But all these valiant volunteers twice over could not have removed ten million people in time. Then an engineer in Star Fleet Merchant Marine named Sabella came up with the novel idea of refitting those new super-convoys with life support and jury-rigged decks. And that turned the corner for us. Starbase 5 renovated two superconvoys to accommodate passengers in an amazingly short time, and after weeks of impossible logistics and unmeetable timetables, we have succeeded in evacuating the entire planet. The galaxy has never seen an operation of this scope before. And I for one fervently hope it never has to again.

From STAR TREK SPACEFLIGHT CHRONOLOGY by Stanley and Fred Goldstein (1980)

Type: Warship

This is far more speculative, since as far as we know there have not been any space warships created yet. Refer to Warship Design, Warship Gallery, Space War: Intro, Space War: Detection, Warship Weapons Intro, , Warship Weapons Exotic, Space War: Defenses, Space War: Tactics, and Planetary Attack.

Fundamentally they are weapons platforms, so by definition they will be carrying various weapons systems. They may or may not have armor or other defenses, they may or may not have human crews. They probably will have an over sized delta-V capacity, and a large thrust capacity so they can jink around and complicate the enemy's targeting solution (i.e., dodge around so you are harder to hit). Lasers will require large amounts of power, and huge heat radiators and heat sinks to cope with waste energy. They will probably be carrying little or nothing that cannot be used to attack the enemy.

Type: Space Ark

Space Arks are an outer-space version of that old Noah story: some cosmic apocalypse is going to obliterate the world, so it behoves the human race to evacuate to another world a breeding population of humans, a civilization starter kit, as much of the worlds scientific knowledge and culture they can cram in, and a viable subset of Terra's ecosystem (with redundancy, none of this "two by two" nonsense). Yes, it is a popular scifi trope.

It is basically a colony ship to establish an interstellar colony. Except the stakes are higher and the build time is limited. The time limit is set by the arrival date of the apocalypse. Designing it won't be easy. If the ship can be designed to be indefinitely habitable (a "worldship") then the journey to a safe place can be done leisurely. But since such ships are generally built in a clawing rush, they have a limited life until their warranty runs out. So the journey has to be as fast as possible.

Another challenge is attempting construction of the space ark while all the selfish people in the entire freaking world try to seize it for their own survival.

The space ark can be a generation ship or a sleeper ship. A popular option is putting an engine on the end of a space colony. A more challenging option is putting an engine on Terra large enough to move the entire planet somewhere safer. But that is out of the scope of "types of spaceships." Or is it?

John Brunner's epic novel THE CRUCIBLE OF TIME is about an alien race whose planet is faced with annihilation by an oncoming nebula. However the focus in the novel is more on the thousands of years before the building of the ark. The aliens are starting with medieval levels of scientific ignorance and do not even know they are in danger. It is a race to see if they can develop enough science to make space arks before the nebula clobbers them.


(ed note: When a crazed army of survivors attacks the site where the Space Arks are being built, things look bleak until one of the main characters starts up the almost-complete first Ark, sets the atomic engines to "1 G", and floats over the attacking hordes in blowtorch mode)

     " To the ship! Into the ship!" Tony cried to them. "Everybody into the ship! Spread the word! Jack! . . . Everybody, everybody into the ship!" There was no alternative.
     Three-fourths of the camp was in the hands of the horde; and the laboratories could not possibly beat off another rush. They could not have beaten back this, if it had been more organized.
     Bullets flew through the dark.
     "To the ship! To the ship!"
     Creeping on hands and knees, from wounds or from caution, and dragging the wounded with them, the men started the retreat to the ship. Women were helping them.
     Yells and whistles warned that another rush was gathering; and this would be from all sides; the laboratories and the ship were completely surrounded.
     Tony caught up in his arms a young man who was barely breathing. He had a bullet through him; but he lived. Tony staggered with him into the ship.
     Hendron was there at the portal of the great metal rocket. He was cooler than any one else. "Inside, inside," he was saying confidently...
     ...The second rush was coming. No doubt of it, and it would be utterly overwhelming. There would be no survivors—but the women. None. For the horde would take no prisoners. They were killing the wounded already—their own badly wounded and the camp's wounded that they had captured.
     Eliot James, a bullet through his thigh, but saved by the dark, crawled in with this information. Tony carried him into the ship.
     They were all in the ship—all the survivors. The horde did not suspect it. The horde, as it charged in the dark, yelling and firing, closed in on the laboratories, clambered in the windows, smashing, shooting, screaming. Meeting no resistance, they shot and bayoneted the bodies of their own men and of the camp's which had been left there.

     Then they came on toward the ship. They suddenly seemed to realize that the ship was the last refuge. They surrounded it, firing at it. Their bullets glanced from its metal. Somebody who had grenades bombed it.
     A frightful flame shattered them. Probably they imagined, at first, that the grenade had exploded some sort of a powder magazine within the huge metal tube, and that it was exploding. Few of those near to the ship, and outside it, lived to see what was happening.

     The great metal rocket rose from the earth, the awful blast from its power tubes lifting it. The frightful heat seared and incinerated, killing at its touch. A hundred of the horde were dead before the ship was above the buildings.
     Hendron lifted it five hundred feet farther, and the blast spread in a funnel below it. A thousand died in that instant. Hendron ceased to elevate the ship. Indeed, he lowered it a little, and the power of the atomic blast which was keeping two thousand tons of metal and of human flesh suspended over the earth, played upon the ground—and upon the flesh on the ground—as no force ever released by man before.
     Tony lay on his face on the floor of the ship, gazing down through the protective quartz-glass at the ground lighted by the garish glare of the awful heat.

     In the midst of the blaring, blinding, screaming crisis, a man on horseback appeared. His coming seemed spectral. He rode in full uniform; he had a sword which he brandished to rally his doomed horde. Probably he was drunk; certainly he had no conception of what was occurring; but his courage was splendid. He spurred into the center of the lurid light, into the center of the circle of death and tumult, stiff-legged in stirrups of leather, like one of the horrible horsemen of the Apocalypse.
     He was, for a flaming instant, the apotheosis of valor. He was the crazed commander of the horde.
     But he was more. He was the futility of all the armies on earth. He was man, the soldier.
     Probably he appeared to live after he had died, he and his horse together. For the horse stood there motionless like a statue, and he sat his horse, sword in hand. Then, like all about them, they also crumpled to the ground.

     Half an hour later, Hendron brought the ship down.

From WHEN WORLDS COLLIDE by Philip Wylie and Edwin Balmer (1933)

(ed note: the inhabitants of the planet are treated to a somewhat close star going nova. Study of the explosion advances science, and also gives the secret of a faster-than-light drive. The project starts to build the first starship.

Then they notice that their own primary star is acting a little peculiarly. With horror they realize it is going to go nova in about nine years. The planetary government embarks on a crash program to make as many space arks as possible. Of course those who will left behind are somewhat unhappy.)

      Even for those barely possible few who did not recognize the man himself, the ceremonial blue and gold robes told the tale: he was the World Consort. His presence could only mean that whatever he had to say was the contribution of the Matriarch herself.
     “I am here essentially to answer the young man’s question,” he said. “There is work that we can do—work for a whole people, for a whole world. One Ertak-drive ship is no longer enough; we want hundreds—even thousands if that is possible. We are transforming the Project into a mass crash program for the survival of the race. We are going to build, man and launch a fleet.”

     Being young, Jom was not immediately able to rid himself of his notion—no, it was more than a notion, it was a fact of his brief experience—that five years was a long, long time in the future. He was astonished to see how rapidly Ertak and his staff forced themselves to make huge decisions, which ordinarily should have been weighed for several months at the very least. Now four or five of these might be made on a single typical day.

     For a sufficient example, take ship design. The Project’s ship on the ways, the Javelin, had been planned as a vessel which would return home well within the lifetime of its original crew. Now it had to be thought of, instead, as a colony-in-flight, able to shelter many generations if necessary.
     But spaceships which will also be colonies are not easily designed from nothing ; and an interstellar ship which was specifically designed not to be a colony cannot speedily be torn down and changed over. When presented with the time-budget for such an operation, Ertak decided almost instantly against it. The Javelin was ordered to be modified in as many small ways as possible, but she was not to be rebuilt, nor was she to be nibbled at drastically enough to risk weakening her present structure. This made sense, but Jorn was not prepared for the corollary decision: that all the Javelin's sister ships were to be built to the same design and with only such minor modifications as the Javelin herself could safely withstand. This decision too was eminently reasonable, but not to a man to whom five years seemed like a long time.

     And as with the ships, so with the world. This decision was not Ertak’s to make, but since the principles were the same, so was the outcome. The whole world was not converted overnight, or at any other time, to the production of interstellar ships, as Jorn had fuzzily imagined the World Consort to have implied. Doom or no doom, the fact remained that the original Javelin at completion would have cost half a billion credits, plus four years in construction time. Her sister ships would cost slightly less than that, but not much—mass production is an almost meaningless term for a structure like a bridge or a skyscraper or a ship, the savings involved running narrowly between two and four per cent per structure.
     Jorn had of course supposed that mere financial cost—and in that word “mere” there resounded hollowly a huge hole in his education—would go by the board in so ultimate an emergency. Like all the poor, money to him was an abstraction, a frivolity, a curse ; as a graduate engineer he knew all about oil, but nobody had bothered to tell him that money is even more necessary and valuable. Skyscrapers, battleships, satellite stations or survival fleets all require a high-energy economy, which means that almost all the goods and services in the world—and hence almost all of the money—must continue to be devoted to keeping that economy at the highest possible level. The farmer may not leap from her combine and take up a hammer on the nearest incomplete interstellar ship; the submarine freighter engineer may not abandon the engines which are propelling titanium ore or sponge platinum from one continent to another; the baker may not cease to make bread; the banker may not take her hands away from the guidance of credit, the raw material of political unity and the only enduring testimonial to man’s confidence in man; even the newscaster may not cease from telling all the rest, who in fact do not know how to hold a hammer and cannot feel or see the escapd fleet growing, that grow it does, and any job well done is an investment in the Project.

     All this takes money; nothing else will serve.

     “Of course we’re trading for the moment on the fact that most of the people don’t really believe a word of it,” Ertak remarked. “They’re willing to go along because the government’s buttered on a little inflation that’s how you ease civilians into any war. But that won’t last long enough. By the end of next year the bombs will start falling, and then they’ll want to run the war themselves, for their own personal protection. That’s when the trouble begins...
     “I don’t see the analogy,” Jorn confessed.
     “I mean that by that time they’ll be beginning to feel the heat—all of them, not just the neurotics who think they can feel it now. It’ll occur to them that the Sun really is going to explode. Then they’ll begin to wonder what they’re really working for : in other words, whether or not what they’re doing is going to get them an entrance ticket to one of our ships. And the moment we have to start paying them in hope instead of in credits, we’ll be in trouble—and there won’t be a ship in the fleet that’s much beyond half done at that point, except of course the Javelin.”
     “But we are going to be carrying passengers,” Jom said hesitantly. “Lots of them."
     “My dear Jorn! Never mind, Ailiss O’Kung says you may be a great navigator ... Of course we’ll be carrying passengers—roughly a hundred for every crewman on the Javelin, and even more on the others. But how many people does that come to? We won’t know until we see how many ships we manage to build before we have to leave, but I’ll tell you this: under the best possible circumstances, the total population of the fleet will be less than the differential birthrate of this planet for one single day. Probably a good deal less.”
     “Still, Director, we won’t be taking the old, or the handicapped or . . . certainly not the newborn . . .”
     “Ah,” Ertak said with a frozen smile. “That makes it look much easier. But let’s do a little simple multiplication, by tens. The Javelin will be able to carry about twenty-five hundred people. If the fleet consists of a hundred such ships—which would astonish me—then it will leave carrying a quarter of a million. Correct ?”

     Jorn began to feel sick. The Director saw it, obviously, but he continued his explanation without mercy.
     “Now let’s suppose that you’ve managed to disqualify twenty-five million people, on sure sound principles. This leaves you with 2,476,000,000 eligible candidates from which to pick 250,000. About one from every ten million. Would you like the job?”
     “No,” Jom said. “Great Ghost, no.”

     Jorn had no time to puzzle over the sudden inaccessibility of the Director; everything abruptly was going too fast. The five years had in fact almost gone by; and the fleet was, both by definition and a long accumulation of miracles, well more than half done. By now, Jorn was better equipped to understand the awful logic of the simple theory of numbers involved, which ruled that a fleet half finished today may tomorrow have to be dubbed, arbitrarily, all the fleet that there is going to be.
     “And we are very close to term now,” Dr. Chase-Huebner told a meeting in the red room. These days she spoke for the Director; if anybody knew why, nobody had been able to tell Jorn. “We have thirty ships. A thirty-first, the Haggard, is far enough along to be counted in.”
     “What about the Assegai?” someone asked.
     “Out of the question. It would take more than a year to finish her, and we haven't got a year. And I’m not just talking about the heat and the storms, either —though both are awful enough already. Public panic is rising so rapidly now that we won’t be able to keep workers on the Assegai another year without promising them all a berth on her; and as you all know, our complement is filled. Believe me, I hate to leave that ship behind —I hate to leave any ship behind, but particularly the Assegai with alt her refinements. But we have to stop somewhere. It would be nice to wait for the Boomerang, too; on paper she’s far and away the trimmest ship of her class on the ways—but at the moment she’s nothing but a keel and a heap of loose Ibeams. This has got to be the end.”
     “Why not call a halt on the Haggard, too?” Kamblin proposed. “She’ll take another five months, it seems.”
     “Because,” Dr. Chase-Huebner said gently, “we have a crew and passengers for the Haggard, and the Director doesn’t mean to leave anyone behind whom we have promised can go.”

     In mid-air in Ertak’s office a siren groaned briefly, urgently, and on Ertak’s desk, just to the left and directly in front of Dr. Chase-Huebner, the orange light went on.
     It had never been on before. It would never go on again. It meant, very simply, that Dr. Chase-Huebner—and Director Ertak?—had already waited too long, and that even the Haggard would now never be finished.
     The Sun, baleful though it had become, was still decades away from its last agony; but the cataclysm was upon them, all the same.

     The truck was covered and there was hardly anything to be seen from it. Jorn and fourteen other crew members of the Javelin clung to the hard benches and craned their necks around each other, trying to peer out the back over the tailgate; but at first the administration building blocked off the view, and then the driver was careening across Salt Flats at a pace which made visibility less important than just hanging on. It was maddening.
     All the same, a general distant roar of human and machine sound, massive and ugly, came rolling clearly over the snarling of the truck’s own engine. If the sputtering of gas guns was a part of that clamor, it could not be distinguished, at this distance, from the boundary fences; but there were louder explosions too—explosive bullets, grenades, even an occasional mortar.
     It was hard to believe that any sort of a mob could have gathered outside that fence, in the middle of one of the most forbidding deserts in this entire hemisphere of the world; but that was what the orange light had been triggered to foretell. And the fact that the mob was already here—and that the truck was already racing for the Javelin—could mean only that it was huge, armed, and at least partially organized.
     And it also meant, Jorn was fervently sure regardless of the evidence, that somebody—a great many somebodies—had badly misjudged Jurg Wester, and the likes of him.

     The flickering night framed over the tailgate of the truck was streaked briefly by the track of a rocket shell. The concussion from the tank-killer hung fire long after the wake of the little missile had vanished, and its residual image after it ; and then, blam, there it came, from somewhere in the middle distance. Obviously it hadn’t been aimed at the truck, which in any event was showing no lights ; but it left behind no doubt that the mob was armed. Of course at this speed a tire blowout would kill Jorn and everyone else almost as instantly—
     The tires screamed and the truck, yawing and lurching, slammed down to a dead stop, piling all fifteen of them up against the back wall of the cab. Accompanying the yell of brakes and tires was the awful grinding, pounding note of gears being stripped: the driver had shifted down into first in order to stop shorter than the brakes could manage alone, trusting to the crew’s field gear to protect them and her own skill to pocket her.

     They were still trying to unscramble themselves from their own swearing black homologous knot when the tailgate clanged down. “Out!" a woman’s voice shouted. “Hit that lift! Lock closes in seven minutes! Move!”
     Jorn recognized the voice. It belonged to the armorer. Well, that explained the drastic driving. She was waiting for them as they unscrambled and struck turf, carrying a hooded torch further hooded by her gauntlet, between two fingers of which she allowed only a razor-edge of red light to shear at the ground. Even in the dim monochrome, however, Jorn could see that she was bleeding a black rill from one nostril.
     For an instant thereafter he was totally confused. Then, against the starlight, he picked out the colossal shaft of the Javelin, sweeping motionlessly into the sky as though she would never end. Beside her, seemingly clinging to one long dully-gleaming curve, was the delicate scaffolding of the elevator, waiting to be extinguished like a flame at the moment of takeoff.

     “That way,” the armorer growled, “that way.” She gestured along the sand and salt with the razor-edge of the torch; but Jorn was already running. He could hear others behind him. Far away, something—a bomb?—burst open with a deep, heavy groan, and a minute temblor shook the desert under his pounding feet.
     Then the aluminum deck of the lift car was ringing with the trampling of boots as they charged aboard, shoving each other and grabbing for cables or struts they could only guess were there. “. . . thirteen . . . fourteen ... Now by the Ghost ... All right, get in, dammit, fifteen!" A whistle warbled shrilly, almost in Jorn’s ear. The cab shuddered, and then, without any pause, lurched skyward with a muscle-wrenching jolt.

     After that, it did not seem to be going anywhere at all, despite the piercing, unpredictable screams it sometimes uttered against its guide-rails, and the jittering of the deck beneath their feet. Nevertheless it was rising, and as it rose, Jorn could see more and more of the outskirts of the base. Now they were seething with light and smoke, all along the perimeter. Tracers criss-crossed the hot night air in all directions. The higher the car inched, the more likely it seemed to Jorn that everyone on it would be riddled before they would be able to reach the faraway airlock of the Javelin.
     Then, ages later, they were high enough to begin to see the general shape of the attack. It was huge. Beyond the immediate, writhing lines of fire along the fences, twinkling processions of vehicles were racing in nearly straight lines over the desert toward Salt Flats. Near the horizon there did indeed seem to be some bombs falling, and some of these small “nominal” atomics. Evidently the government still controlled the air—which was good as far as it went, but the planes would be under strict orders to stay well away from the ships, where the main part of the mob obviously was concentrating, and hence the only place where a really comprehensive explosion might be decisive.
     The lift quivered and rose a little faster. It brought them all high enough to test their handholds with a heavy buffeting of wind—though the wind seemed to be just as hot as the air on the desert itself had been. There would be no more cool winds on this planet, not at any altitude at which a man could expect to breathe, not even on the mountains.

     Another rocket shell went searing past in a high hazy arc. Jorn stopped breathing for an instant. That one was close. Didn’t they realize that they might hit the ship itself? For that matter, didn’t they know that they couldn’t pack all of those thousands of people into the Javelin and her sisters ? Didn’t they know that they’d wreck her, just trying? Sure, there were three other ships standing on Salt Flats, but—
     But as he realized the futility of trying to think like a mob, his mind repeated, “thousands of people,” and quailed. That mob was being held off only by the stand-bys and there were very few of those any more, certainly far from a full extra crew for each ship. They had been weeded; and judging by the rocket shells, many of the rejects were now howling on the other side of the fence. Despite the standby training, and the supernal lethality of their gear, the stand they were making was suicidal. They would have to fall back, or—
     But they did not fall back. Not this time.
     They were broken open.

     About two miles northwest of the administration building, the line of flame sagged inward. Then it went dark along at least half a mile; the fence was down. Outside, there was a flaming surge of movement toward the hole like surf foaming around a whirlpool.
     The cab came to a bouncing stop in the middle of the sky.
     “All right, inside!” the armorer shouted. “Lock closes in one minute! Inside—shuffle or dust!”
     Had that whole crawling ascent been only six minutes long? But there was no time for postmortems. The sixteen of them were packed into the lock like fish in a jar, and the outer door swung ponderously, unfeelingly shut on the battle and on the whole outside world . . . for good.
     As it sealed, a hairline semicircle of light, intolerably brilliant after the near-blackness of the field, began to widen on the other side of the lock. Jorn was momentarily startled; it had not occurred to him that the interior of the ship might be fully lit—although, since she had no ports, there was no reason why she shouldn’t have been; and besides, her passengers had been living aboard her ever since she was finished. In the first influx of light he was startled to find Ailiss O’Kung standing next to him, white and sweating with strain.

     “Very good,” the armorer said, a little more quietly, but not much. “Posts, ladies and gentlemen. And thank you.”
     Proper enough, Jorn thought deliriously, since the armorer was the only one in the party who was not an officer. Still the speech had all the irrationality of a dream.
     Everything had been rehearsed over and over long before this. Jorn headed for the control barrel almost by instinct, Ailiss trotting by his side. In the big blinking cavern he ran a fast tally of his navigation section and found them there; he did not stop to count Ailiss’ crew, but he had a vague feeling that she was at least one officer short.
     Ertak was there, hunched in the command chair above them. That was his right, since the Javelin was the flagship. But it was the first time that Jorn had seen him in five years; it increased the dream-like feeling.

     The Director did not turn around. He did not even seem to hear what was going on behind him. After a moment, however, he spoke into a chest microphone, and all the desk screens came to life, including Jom’s own. Once again he had a view of the scene outside.
     It no longer really looked like a battle, but more like a carnival, confusing, gay with light, without real meaning. Nevertheless, from this height Jom was able to see that a miracle had happened around the breach at the fence. Somehow, whoever had been generalling the defense had managed to pinch off the inflow, clean up the stragglers, and order a retreat. The irregular closed curve of fire, curiously amoeboid, was well inside the fences everywhere, and drawing closer and closer to the ships; but it was still unbroken.

     Beside Jorn’s right hand he heard a razzy muttering, and reached guiltily for his operations helmet. Inside it, Ertak’s voice was saying:
     ". . . and maintain routine identification signal census in a continuous cycle. Field officers, continue to hold ground by the Haggard and the Assegai; they both look finished and we want the rabble to assume that they are. On Signal Red, flatten out toward the Assegai; on Signal Blue, let them have her. Lifts are down on Javelin and Quarrel; repeat, lifts down on Javelin and Quarrel . . . Congratulations, Deep Station. To all hands: Deep Station reports it has secured all five ships. . . . Census? Census, report! . . . Field officers, Signal Red, this is Signal Red, execute. . . To all hands: Deep Station is launching . . , Census? . . . Field officers, supersede previous orders. On blue signal, yield both Assegai and Boomerang and fall back toward Javelin. Fall back toward Javelin, we will be last off. . . Attention Quarrel, cycle airlock and begin countdown; we won't need you for personnel.”

     The line of fire bulged inward toward the Javelin, and then toward the incomplete ships. Then there was an even deeper bulge toward the Quarrel.
     “Field officers, blue signal will be on count of zero. At the signal, yield the field and board the Javelin’s lift. One minute allowed for boarding, repeat one minute. Counting toward blue signal: five . . . four . , . three . . . two . . . one . . . zero. Signal Blue! Signal Blue!”
     The line swept inward on all sides—and then suddenly it disappeared utterly. There was noi longer even a part of it to be seen. Instead there were only the torches and vehicle lights of the mob, pouring inward toward the three ships they thought they had gained. In a barely perceptible flickering of smallarms fire, what little there was left of the standby crew funnelled toward the lift shaft of the Javelin, trying to disengage.
     “Census, I have pips for twenty-one survivors and a load estimate of eighteen on the lift. Confirm, please. . . . All right, nineteen now. Time’s up. Lift crew, haul them. . . . Absolutely not. Quarrel will leave in six minutes exactly. If we wait for three stragglers, all twenty-one will die. Haul!”

     A minute went by. The mob continued to concentrate around the bases of the “captured” ships, like phosphorescent ants, until each of them seemed to be standing in a spreading pool of light. The pool around the Boomerang, however, quickly began to seep away toward the others; close up it was self-evident that that ship was radically incomplete.
     “To all hands: Deep Station has launched all five ships. We have garbled reports from other stations indicating at least eighteen more either secured or already launched. There are also still two stations holding radio silence: we are hoping this means that their locations remain unknown and they are undergoing no attack.”

     Three minutes.

     “Passenger census . . . Well, that’s what they get for sightseeing; we warned them. Certainly it could be a lot worse. . . Airlock crew, prepare to admit standbyes.”
     Nobody could call them standbyes after tonight.

     Four minutes. There was turmoil now in the pools of light around the Assegai and the Haggard. Little sparks of light were clambering slowly up the scaffolding of their lift-shafts ; obviously they had discovered that the lifts themselves were inoperable.

     Five minutes. The airlock was open now, gaping for the nineteen seared heroes. The mob was beginning to ooze tentatively toward the Quarrel.
     “. . . seventeen, eighteen, nineteen. Cycle airlock. Field officers, welcome aboard. Get that thing closed, you’ve got four seconds—”


     The Quarrel vanished. On Salt Flats the pools of light were still visible, but they looked dimmer, and completely frozen: truck lights left on, torches fallen from hands. . . . The concussion had probably killed many of them. The rest would be likely to be still unconscious when the Javelin left.
     “A clean takeoff,” Ertak’s voice said calmly. “Ship’s officers, begin countdown. We will follow in eight minutes.” He paused and seemed to check some board hidden by his chest. Then he added, “To. all hands: congratulations. The Javelin is the last ship able to leave, and the last of these still on the ground. Twenty-nine others are all already on their way.”
     Thirty ships, Jom thought numbly. Thirty ships.
     “Correction, we are thirty-one in all. We have a signal from the Kestrel. She is damaged but off safely.”

     There was a ragged cheer in the earphones. Jom did not join in it. What difference could one ship make? What difference would ten have made?
     “Census . . . thank you. To all hands : we now have a final population check. We are carrying seventy-five thousand people, give or take about a hundred. We have escaped—and by that token, we know that we will survive. Take-off in thirty seconds.”
     We have escaped ... we will survive. And yet . . . how many died when the Quarrel vanished, and the lights were stilled on Salt Flats? How many more would die to the departure of the Javelin? How many had been killed to keep them out of the ships, all over the world?
     We will survive. But who are we to survive?

From ...AND ALL THE STARS A STAGE by James Blish (1960)

(ed note: in the novel they are trying to guard an underground shelter instead of a space ark. But the same principles apply to defense)

As Seaton assumed, the near-collision of suns which had affected so disastrously the planet Valeron did not come unheralded to overwhelm a world unwarned, since for many hundreds of years her civilization had been of a high order indeed. Her astronomers were able, her scientists capable, the governments of her nations strong and just. Years before its occurrence the astronomers had known that the catastrophe was inevitable and had calculated dispassionately its every phase — to the gram, the centimeter, and the second.

With all their resources of knowledge and of power, however, it was pitifully little that the people of Valeron could do; for of what avail are the puny energies of man compared to the practically infinite forces of cosmic phenomena? Any attempt of the humanity of the doomed planet to swerve from their courses the incomprehensible masses of those two hurtling suns was as surely doomed to failure as would be the attempt of an ant to thrust from its rails an onrushing locomotive.

But what little could be done was done; done scientifically and logically; done, if not altogether without fear, at least in as much as was humanly possible without favor. With mathematical certainty were plotted the areas of least strain, and in those areas were constructed shelters. Shelters buried deeply enough to be unaffected by the coming upheavals of the world's crust; shelters of unbreakable metal, so designed, so latticed and braced as to withstand the seismic disturbances to which they were inevitably to be subjected.

Having determined the number of such shelters that could be built, equipped, and supplied with the necessities of life in the time allowed, the board of selection began its cold-blooded and heartless task. Scarcely one in a thousand of Valeron's teeming millions was to be given a chance for continued life, and they were to be chosen only from the children who would be in the prime of young adulthood at the time of the catastrophe.

These children were the pick of the planet: flawless in mind, body, and heredity. They were assembled in special schools near their assigned refuges, where they were instructed intensively in everything that they would have to know in order that civilization should not disappear utterly from the universe.

Such a thing could not be kept a secret long, and it is best to touch as lightly as possible upon the scenes which ensued after the certainty of doom became public knowledge.

Humanity both scaled the heights of self-sacrificing courage and plumbed the very depths of cowardice and depravity.

Characters already strong were strengthened, but those already weak went to pieces entirely in orgies to a normal mind unthinkable. Almost overnight a peaceful and lawabiding world went mad — became an insane hotbed of crime, rapine, and pillage unspeakable. Martial law was declared at once, and after a few thousand maniacs had been ruthlessly shot down, the soberer inhabitants were allowed to choose between two alternatives. They could either die then and there before a firing squad, or they could wait and take whatever slight chance there might be of living through what was to come — but devoting their every effort meanwhile to the end that through those selected few the civilization of Valeron should endure.

Many chose death and were executed summarily and without formality, without regard to wealth or station. The rest worked. Some worked devotedly and with high purpose, some worked hopelessly and with resignation. Some worked stolidly and with thoughts only of the present, some worked slyly and with thoughts only of getting themselves, by hook or by crook, into one of those shelters. All, however, from the highest to the lowest, worked.

Since the human mind cannot be kept indefinitely at high tension, the new condition of things came in time to be regarded almost as normal, and as months lengthened into years the routine was scarcely broken. Now and then, of course, one went mad and was shot; another refused to continue his profitless labor and was shot; still another gave up the fight and shot himself. And always there were the sly the self-seekers, the bribers, the corruptionists — willing to go to any lengths whatever to avoid their doom. Not openly did they carry on their machinations, but like loathsome worms eating at the heart of an outwardly fair fruit. But the scientists, almost to a man, were loyal. Trained to think, they thought clearly and logically, and surrounded themselves with soldiers and guards of the same stripe. Old men or weaklings would have no place in the post-cataclysmic world and there were accommodations for only the exactly predetermined number; therefore only those selected children and no others could be saved or would. And as for bribery, threats, blackmail, or any possible form of racketry or corruption — of what use is wealth or power to a man under sentence of death? And what threat or force could sway him?

Wherefore most of the sly were discovered, exposed, and shot.

Time went on. The shelters were finished. Into them were taken stores, libraries, tools and equipment of every sort necessary for the rebuilding of a fully civilized world. Finally the "children," now in the full prime of young manhood and young womanhood, were carefully checked in. Once inside those massive portals they were of a world apart.

They were completely informed and completely educated; they had for long governed themselves with neither aid nor interference; they knew precisely what they must face; they knew exactly what to do and exactly how to do it. Behind them the mighty, multiply seals were welded into place and broken rock by the cubic mile was blasted down upon their refuges.

Day by day the heat grew more and more intense. Cyclonic storms raged ever fiercer, accompanied by an incessant blaze of lightning and a deafeningly continuous roar of thunder. More and ever more violent became the seismic disturbances as Valeron's very core shook and trembled under the appalling might of the opposing cosmic forces.

Work was at an end and the masses were utterly beyond control. The devoted were butchered by their frantic fellows; the hopeless were stung to madness; the stolid were driven to frenzy by the realization that there was to be no future; the remaining sly ones deftly turned the unorganized fury of the mob into a purposeful attack upon the shelters, their only hope of life.

But at each refuge the rabble met an unyielding wall of guards loyal to the last, and of scientists who, their work now done, were merely waiting for the end. Guards and scientists fought with rifles, ray-guns, swords, and finally with clubs, stones, fists, feet and teeth. Outnumbered by thousands they fell and the howling mob surged over their bodies. To no purpose. Those shelters had been designed and constructed to withstand the attacks of Nature gone berserk, and futile indeed were the attempts of the frenzied hordes to tear a way into their sacred recesses.

Thus died the devoted and high-souled band who had saved their civilization; but in that death each man was granted the boon which, deep in his heart, he craved. They had died quickly and violently, fighting for a cause they knew to be good. They did not die as did the members of the insanely terror-stricken, senseless mob... in agony... lingeringly... but it is best to draw a kindly veil before the horrors attendant upon that riving, that tormenting, that cosmic outraging of a world.

The suns passed, each upon his appointed way. The cosmic forces ceased to war and to the tortured and ravaged planet there at last came peace. The surviving children of Valeron emerged from their subterranean retreats and undauntedly took up the task of rebuilding their world. And to such good purpose did they devote themselves to the problems of rehabilitation that in a few hundred years there bloomed upon Valeron a civilization and a culture scarcely to be equaled in the universe.

For the new race had been cradled in adversity. In its ancestry there was no physical or mental taint or weakness, all dross having been burned away by the fires of cosmic catastrophe which had so nearly obliterated all the life of the planet. They were as yet perhaps inferior to the old race in point of numbers, but were immeasurably superior to it in physical, mental, moral, and intellectual worth.

Immediately after the Emergence it had been observed that the two outermost planets of the system had disappeared and that in their stead revolved a new planet. This phenomenon was recognized for what it was, an exchange of planets; something to give concern only to astronomers.

No one except sheerest romancers even gave thought to the possibility of life upon other worlds, it being an almost mathematically demonstrable fact that the Valeronians were the only life in the entire universe. And even if other planets might possibly be inhabited, what of it? The vast reaches of empty ether intervening between Valeron and even her nearest fellow planet formed an insuperable obstacle even to communication, to say nothing of physical passage. Little did anyone dream, as generation followed generation, of what hideously intelligent life that interloping planet bore, nor of how the fair world of Valeron was to suffer from it.

From SKYLARK OF VALERON by E. E. "Doc" Smith (1934)

Type: Covered Wagon

This is a minimal cheap spacecraft used by Maw and Paw to travel to the asteroid belt in order to set up a homestead.

They are lofted into orbit by either a chemical booster or laser launch service. Or manufactured in orbit; with Maw, Paw, and their brood buying tickets on a passenger service then taking possession.

At the cheapest they are basically a habitat module which rents propulsion services from a space tug, momentum bank, or a power-beaming service. Mid-range models will be something like a hydro ship, with some efficient and cheap (but low thrust) integral propulsion system. Top-of-the-line will be something approaching a full blown space tug, with enough delta-V to haul cargo.

These are examined in more detail here.

Type: Hydro Ship

As mentioned in the section on Ice Mining, when it comes to the industrialization and colonization of space, water is the most valuable substance in the Universe. Among other things it can be used for life support, reaction mass, and radiation shielding.

There will be lots of robot asteroid miners, many who will specialize in volatiles such as water. These include the CFW NEO MicroMiner, the Robot Asteroid Prospector (RAP), the Asteroid Provided In-Situ Supplies (APIS), the Kuck Mosquito, the Water Truck, and the Water Ship.

There is a prototype life support system (and cosmic ray radiation shield) called the Water Wall that is mostly composed of water.

There is even a rocket engine called the Microwave Electrothermal Thruster which uses water for reaction mass, has a respectable exhaust velocity of up to 9,800 m/s, is very reliable, and can easily be powered by solar panels. Oh, and unlike ion drives, you can make massed clusters of the little darlings and they won't electromagnetically interfere with each other. You can make an array of 400 or so to produce a whopping 12,000 Newtons of thrust. They are also very easy to repair. Even by an amateur.

Best of all, if you mix water with a binder and freeze it, you get Pykrete, which is a building material. You could even use it to, well, build a spaceship or space station with. This turned up in Neal Stephenson's science fiction novel Seveneves, but there is no reason it couldn't be done in reality.

Which means you could make a spacecraft that was mostly water.

For an example, see the Spacecoach below.

Now this would not be suitable to make space battleships or space fighters with, but it would be dandy for interplanetary wagon trains for Maw and Paw Kettle to go homesteading in the asteroid belt. Mostly made of water, which cheaply comes from in-situ resource utilization. Not the strongest nor the most durable, but very affordable.

This would also be useful for somebody with limited access to raw materials. Say, refugees from a galactic war entering a remote uninhabited star system, carrying only whatever odd bits of material and tools that will fit into the cargo space not filled with refugees.


      Most of all he liked to watch the rings. At the left, they emerged from behind Saturn, a tight, bright triple band of orange fight. At the right, their beginnings were hidden in the night shadow, but showed up closer and broader. They widened as they came, like the flare of a horn, growing hazier as they approached, until, while the eye followed them, they seemed to fill the sky and lose themselves.
     From the position of the Scavenger fleet just inside the outer rim of the outermost ring, the rings broke up and assumed their true identity as a phenomenal cluster of solid fragments rather than the tight, solid band of light they seemed.
     Below him, or rather in the direction his feet pointed, some twenty miles away, was one of the ring fragments. It looked like a large, irregular splotch, marring the symmetry of space, three quarters in brightness and the night shadow cutting it like a knife. Other fragments were farther off, sparkling like star dust, dimmer and thicker, until, as you followed them down, they became rings once more.
     The fragments were motionless, but that was only because the ships had taken up an orbit about Saturn equivalent to that of the outer edge of the rings.
     The day before, Rioz reflected, he had been on that nearest fragment, working along with more than a score of others to mold it into the desired shape. Tomorrow he would be at it again.

     He strengthened pseudo-grav and lifted the projector a bit. He released pseudo-grav, insuring that the projector would stay in place for minutes even if he withdrew support altogether. He kicked the cable out of the way (it stretched beyond the close “horizon” to a power source that was out of sight) and touched the release.
     The material of which the fragment was composed bubbled and vanished under its touch. A section of the lip of the tremendous cavity he had already carved into its substance melted away and a roughness in its contour had disappeared.
     “Try it now,” called Rioz.
     Swenson was in the ship that was hovering nearly over Rioz's head.
     Swenson called, “All clear?”
     “I told you to go ahead.”
     It was a feeble flicker of steam that issued from one of the ship's forward vents. The ship drifted down toward the ring fragment. Another flicker adjusted a tendency to drift side-wise. It came down straight.
     A third flicker to the rear slowed it to a feather rate.
     Rioz watched tensely. “Keep her coming. You'll make it. You'll make it.”
     The rear of the ship entered the hole, nearly filling it. The bellying walls came closer and closer to its rim. There was a grinding vibration as the ship's motion halted.
     It was Swenson's turn to curse. “It doesn't fit,” he said.
     Rioz threw the projector ground-ward in a passion and went flailing up into space. The projector kicked up a white crystalline dust all about it, and when Rioz came down under pseudo-grav, he did the same.
     He said, “You went in on the bias, you dumb Grounder.”
     “I hit it level, you dirt-eating farmer.”
     Backward-pointing side jets of the ship were blasting more strongly than before, and Rioz hopped to get out of the way.
     The ship scraped up from the pit, then shot into space half a mile before forward jets could bring it to a halt.
     Swenson said tensely, “We'll spring half a dozen plates if we do this once again. Get it right, will you?”
     “I'll get it right. Don't worry about it. Just you come in right.”
     Rioz lumped upward and allowed himself to climb three hundred yards to get an over-all look at the cavity. The gouge marks of the ship were plain enough. They were concentrated at one point halfway down the pit. He would get that.
     It began to melt outward under the blaze of the projector.
     Half an hour later the ship snuggled neatly into its cavity, and Swenson, wearing his space suit, emerged to join Rioz.
     Swenson said, “If you want to step in and climb out of the suit, I'll take care of the icing.”
     “It's all right,” said Rioz. “I'd just as soon sit here and watch Saturn.”
     He sat down at the lip of the pit. There was a six-foot gap between it and the ship. In some places about the circle, it was two feet; in a few places, even merely a matter of inches. You couldn't expect a better fit out of handwork. The final adjustment would be made by steaming ice gently and letting it freeze into the cavity between the lip and the ship.
     Saturn moved visibly across the sky, its vast bulk inching below the horizon.
     Rioz said, “How many ships are left to put in place?”
     Swenson said, “Last I heard, it was eleven. We're in now, so that means only ten. Seven of the ones that are placed are iced in. Two or three are dismantled.” “We're coming alone fine.”
     “There's plenty to do yet. Don't forget the main jets at the other end. And the cables and the power lines."

     It had all seemed perfectly logical back on Mars, but that was Mars. He had worked it out carefully in his mind in perfectly reasonable steps. He could still remember exactly how it went. It didn't take a ton of water to move a ton of ship. It was not mass equals mass, but mass times velocity equals mass times velocity. It didn't matter, in other words, whether you shot out a ton of water at a mile a second or a hundred pounds of water at twenty miles a second. You got the same velocity out of the ship.
     That meant the jet nozzles had to be made narrower and the steam hotter. But then drawbacks appeared. The narrower the nozzle, the more energy was lost in friction and turbulence. The hotter the steam, the more refractory the nozzle had to be and the shorter its life. The limit In that direction was quickly reached.
     Then, since a given weight of water could move considerably more than its own weight under the narrow-nozzle conditions, it paid to be big. The bigger the water-storage space, the larger the size of the actual travel-head, even in proportion. So they started to make liners heavier and bigger. But then the larger the shell, the heavier the bracings, the more difficult the weldings, the more exacting the engineering requirements. At the moment, the limit in that direction had been reached also.
     And then he had put his finger on what had seemed to him to be the basic flaw—the original unswervable conception that the fuel had to be placed inside the ship; the metal had to be built to encircle a million tons of water.
     Why? Water did not have to be water. It could be ice, and ice could be shaped. Holes could be melted into it. Travel-heads and jets could be fitted into it. Cables could hold travel-heads and jets stiffly together under the influence of magnetic field-force grips.
     Long felt the trembling of the ground he walked on. He was at the head of the fragment. A dozen ships were blasting in and out of sheaths carved into its substance, and the fragment shuddered under the continuing impact.
     The ice didn't have to be quarried. It existed in proper chunks in the rings of Saturn. That's all the rings were — pieces of nearly pure ice, circling Saturn. So spectroscopy stated and so it had turned out to be. He was standing on one such piece now, over two miles long, nearly one mile thick. It was almost half a billion tons of water, all in one piece, and he was standing on it.
     But now he was face to face with the realities of life. He had never told the men just how quickly he had expected to set up the fragment as a ship, but in his heart, he had imagined it would be two days. It was a week now and he didn't dare to estimate the remaining time. He no longer even had any confidence that the task was a possible one. Would they be able to control jets with enough delicacy through leads slung across two miles of ice to manipulate out of Saturn's dragging gravity?
     Drinking water was low, though they could always distill more out of the ice. Still, the food stores were not in a good way either.
     Some of the men were having trouble with the cables. They had to be laid precisely; their geometry had to be very nearly perfect for the magnetic field to attain maximum strength. In space, or even in air, it wouldn't have mattered. The cables would have lined up automatically once the juice went on.
     Here it was different. A gouge had to be plowed along the planetoid's surface and into it the cable had to be laid. If it were not lined up within a few minutes of arc of the calculated direction, a torque would be applied to the entire planetoid, with consequent loss of energy, none of which could be spared. The gouges then had to be re-driven, the cables shifted and iced into the new positions.
     The men plodded wearily through the routine.

     Long had no assurance that it would work. Even if the jets would respond to the distant controls, even if the supply of water, which depended upon a storage chamber opening directly into the icy body of the planetoid, with built-in heat projectors steaming the propulsive fluid directly into the driving cells, were adequate, there was still no certainty that the body of the planetoid without a magnetic cable sheathing would hold together under the enormously disruptive stresses.
     “Ready!” came the signal in Long's receiver.
     Long called, “Ready!” and depressed the contact.
     The vibration grew about him. The star field in the visiplate trembled.
     In the rear-view there was a distant gleaming spume of swiftly moving ice crystals.
     “It's blowing!” was the cry.
     It kept on blowing. Long dared not stop. For six hours, it blew, hissing, bubbling, steaming into space; the body of the planetoid converted to vapor and hurled away.

     The flotilla, welded into a single unit, was returning over its mighty course from Saturn to Mars. Each day it flashed over a length of space it had taken nine days outward. Ted Long had put the entire crew on emergency. With twenty-five ships embedded in the planetoid taken out of Saturn's rings and unable to move or maneuver independently, the co-ordination of their power source into unified blasts was a ticklish problem. The jarring that took place on the first day of travel nearly shook them out from under their hair.
     That, at least, smoothed itself out as the velocity raced upward under the steady thrust from behind. They passed the one-hundred-thousand-mile-an-hour mark late on the second day, and climbed steadily toward the million-mile mark and beyond.
     Long's ship, which formed the needle point of the frozen fleet, was the only one which possessed a five-way view of space. It was an uncomfortable position under the circumstances. Long found himself watching tensely, imagining somehow that the stars would slowly begin to slip backward, to whizz past them, under the influence of the multi-ship's tremendous rate of travel.

     “You see that?” Sankov, pointing.
     “Hey!” cried a reporter. “It's a ship!”
     A confused shouting came from the adjoining room.
     It wasn't a ship so much as a bright dot obscured by a drifting white cloud. The cloud grew larger and began to have form. It was a double streak against the sky, the lower ends billowing out and upward again. As it dropped still closer, the bright dot at the upper end took on a crudely cylindrical form.
     It was rough and craggy, but where the sunlight hit, brilliant high lights bounced back.
     The cylinder dropped toward the ground with the ponderous slowness characteristic of space vessels. It hung suspended on those blasting jets and settled down upon the recoil of tons of matter hurling downward like a tired man dropping into his easy chair.
     And as it did so, a silence fell upon all within the dome. The women and children in one room, the politicians and reporters in the other remained frozen, heads craned incredulously upward.
     The cylinder's landing flanges, extending far below the two rear jets, touched ground and sank into the pebbly morass. And then the ship was motionless and the jet action ceased.
     But the silence continued in the dome. It continued for a long time.
     Men came clambering down the sides of the immense vessel, inching down, down the two-mile trek to the ground, with spikes on their shoes and ice axes in their hands. They were gnats against the blinding surface.
     One of the reporters croaked, “What is it?”
     “That,” said Sankov calmly, “happens to be a chunk of matter that spent its time scooting around Saturn as part of its rings. Our boys fitted it out with travel-head and jets and ferried it home. It just turns out the fragments in Saturn's rings are made up out of ice.”
     He spoke into a continuing deathlike silence. ”That thing that looks like a spaceship is just a mountain of hard water. If it were standing like that on Earth, it would be melting into a puddle and maybe it would break under its own weight. Mars is colder and has less gravity, so there's no such danger.
     “Of course, once we get this thing really organized, we can have water stations on the moons of Saturn and Jupiter and on the asteroids. We can scale in chunks of Saturn's rings and pick them up and send them on at the various stations. Our Scavengers are good at that sort of thing.
     “We have all the water we need. That one chunk you see is just under a cubic mile-or about what Earth would send us in two hundred years. The boys used quite a bit of it coming back from Saturn. They made it in five weeks, they tell me, and used up about a hundred million tons. But, Lord, that didn’t make any dent at all in that mountain. Are you getting all this, boys?”

From THE MARTIAN WAY by Isaac Asimov (1952)

      So maybe it was Gallagher and his glacier that changed the times, and not the times that fitted Gallagher.
     A pioneer is a man who goes out into the unknown and solves equations to the best of his ability as he meets them. In that respect, Gallagher was a pioneer, and I knew that in that respect I wasn’t. That hurt the ever-living soul of me, underneath all the degrees and certificates that said I was captain of a ship and he wasn’t. An engineer is a man who gets a job done, and in that respect Gallagher was an engineer. I didn’t know whether I was an engineer or not, for I had the book learning, but the ship was a push-button affair that took some handling but that mostly took automatics; and the Port Inspector was the one who said how the automatics would be structured. Gallagher had as good a piece of paper to prove he was an engineer as I did, but he held that piece of paper in great contempt, except when he needed a job, which was a good part of the time since, though he was an engineer with a spacelanes-long reputation, he never had developed a talent for staying on a company ship. As a pioneer, he never had been able to latch onto a colony, company, or otherwise, and stay, for he had a sociable nature that needed to be out and visiting around the spaceways.
     Gallagher’s name was black in the company books. He’d jump a ship or stow away out of a colony as soon as sign the papers.
     So now he sat, mostly in Joe ’s Bar, and waited for a ship to orbit that was setting a course the way he wanted to go. How he was planning to sign on with his name so black in the books, he wasn’t saying.

     But when my ship orbited, and us heading for Altura, there was a small series of untraceable incidents that left my engineer in the hospital. At the same time, I got the news of the “incidents,” Gallagher presented himself shipside with his piece of paper.
     “Your next port is Altura, Captain Harald Dundee,” he said proud-like. His name was N. N. Gallagher, and they called him “Dublin” as a pun and for courtesy of his origin. He stood six feet tall in my cabin, his red hair nearly brushing the topsides, making me feel small and a little insignificant for all my fine uniform, for I clear that ceiling by a good four inches.
     “And,” he said, “it’s toward Altura I’m headin’. Now, seeing as it’s not rightly your fault you’re minus an engineer for the course, I’ll take on the job without much cost to you. There’s a glacier that’s orbiting towards Altura. You can compute to intersect her within three hours of your port. I’ll take on your engineer’s post that far and charge you naught, if you’ll put me aboard that glacier, me and my equipment. And your assistant engineer can take her in from there.”

     Well, that was that, but when I found out what Gallagher meant by equipment, I nearly reneged again. The holds would take it, but we’dl be shipping heavy.
     “You’ll be heavy only so long as I’m aboard, and I’ll have your drive talking so pretty she’ll use less mass than if you were running light with anybody else to engineer her,” says Gallagher modestly. “Your assistant will have a light ship to take in, and the motors already purring.”
     The equipment included one of the old Antolaric drives that used to power the ships they sent out when man first entered space, and it was as massive as the old ships used to be. Then there were supplies to last a man for months, but those weren’t much; and machinery enough to stock a small shop.

     I didn’t understand Gallagher, but I knew him for a breed that caught at the heart of me, for we were both from the old country and we were both out in the new spaceways. There was a kinship between us I couldn’t deny, though the frictions said we were alien, and me a corporation man.
     I understood the man even less when we matched courses with his glacier and I had him and his equipment drifted over to it. It couldn’t have been more than a mile the long way, and a quarter mile through; an ungainly hunk of ice idling through space. What the man could want with it was more than I could see. There were plenty of steel meteorites that size, if Gallagher wanted to make himself a meteor ship—and I admit that seeing that old drive was the first inkling I’d got of such a use. But ice? Then I realized. A steel meteor wouldn’t have given him reaction mass for his fusion chamber, but that ice was a good part hydrogen, and that would be his mass.

     Well, I’d be a few days planetbound, and I spent the first of them partly wandering the company town, partly in the port bar. By the end of the fourthday, I was so furious with Gallagher that I was making up conversations with him, telling him off. And, if you come right down to it, curious. I couldn’t figure how he was going to manage the job alone. I had to see.
     By midnight I’d rationalized myself into good reasons. The man was daft. He was alone on an iceberg, drifting helplessly in space. By now he’d have realized how helplessly. The least I could do—now that his senses had had a chance to reorganize—was to offer him an oiler’s job to get him out of the mess he’d talked himself into. I wouldn’t leave a dog alone out there, I told myself. I owed him a chance to stow away honorably.
     I rented a small interplanet scout, and I headed back for Gallagher's glacier.

     What I expected to find I’m not sure. What I found was the glacier—lonely and sparkling cold —and I could make out Gallagher’s vac-suited figure working on its surface as I matched orbit two kilometers off.
     Since he was on the surface and in a vac suit, I hailed him over the ship’s suit comm, but he failed to answer, and I maneuvered the scout in closer, seeking a place to tie up. That’s when I got an answer.
     “Sheer off, you lunkhead,” came his voice. “I’ll not have you upsetting my balances here.” I was readying a tart reply when he went on. “Anyhow, this is already claimed."
     “Okay, Dublin,” I said. “If you’re too proud to let your former captain see the mess you’ve got into, I’ll be heading back to port. I was just being sociable anyhow.”
     The figure stood and waved, and Gallagher’s tones, hardly less gruff than before, came back over the suit comm. “Neighborly of you, captain. Take her around on the far side and hitch up to a mooring line. But gently, mind you. I’ll still not have you upsetting my balance.
     I was blessed if I could see what he might have in mind about balances, but I eased the scout around to the far side, and that’s when I got my first good look at what Gallagher had been doing.

     There was a bubble,dome anchored firmly to one of the smoother parts of the big ice chunk, and a half-dozen standard bourdon mooring tubes—long, snaky pipes of plastic inflated with gas—that extended out from the surface and to which various “dumps” had been attached. The bubble dome was fair enough; normal equipment for airless planetary living. And the bourdon mooring tubes were normal, if they were attached securely enough to the iceberg.
     I hesitated before mooring to a vacant tube. They’d attach to the scout all right; and if they were moored securely at the far end, fine. But if they weren’t? Well, I’d moor, I decided, and keep an eye on the scout. If it pulled the line loose and started to drift, I could catch it in the first few minutes with the rockets on my suit.
     I nudged up to the tube and was rewarded with the hollow clink of a magnalock. The line was a good kilometer long, but I could see a tiny shuttlebug start its whirring way up the mooring line, so I’d have fast travel going in. Fully automatic, that response; keyed to the impulse of the magnalock. Gallagher was doing better than might have been expected.
     While I waited, I looked over the cargo dumps attached to the other tubes. Nothing but the things we had left, of course. And there was the Antolaric drive—not moored to a tube, but carefully stanchioned directly at the far end of the berg itself, lined up with the balance point of the berg as though it were nudging the glacier from behind.
     A pushberger? I asked myself sarcastically. Is he planning to push the damned berg to the nearest planet? It won’t work that way, I assured myself. A drive is internal to the ship. Necessarily, I emphasized warily to myself, but with the haunting feeling that maybe I was missing something, the memory of the Starfire’s tuning fresh upon me.

     The shuttlebug arrived, and I reached out to grasp the awkward thing, flinging my legs over the upside-down crossbar of the T, and grasping the pipe that led to the tiny foot-long motor firmly clamped to a plastic track along the side ofthe mooring tube. I nudged the trigger and got the giddy sensation of being thrown forward at nearly half a gee as the tiny electric motor whined along the semigeared track; but the acceleration was brief, and I seemed more to be floating than actually riding as I descended towards the glacier.
     It’s a funny feeling, watching a glacier come up at you. You’re not actually falling toward it, nor it toward you, but it feels like it. All directions are up from the largest object, when you’re in a vac suit in space—or even when you’re in a small scout. So if you’re “up” from the big object and you’re approaching it, you’re falling—at least in your mind’s eye, and it’s hard to remember that it’s just travel on a straight line.
     The glacier “below” me was a spread-out panorama, nearing rapidly, and as it neared I could make out curious black spots. Huge black spots. Faults? No, they were too regular. Paint? Hardly. Probably radiator surfaces. Very probably, from the looks. But how had the man spread radiators directly on an ice surface? And how the devil had one man handled a standard radiator surface at all?
     I postponed my curiosity. I’d have at least an hour or so to inspect what had been done while Gallagher made his way around the glacier, and I’d not waste the time.

     But as the shuttlebug threw me into deceleration for the landing (and I got the feeling of falling up), I saw a suited figure emerge from the bubble dome near the terminus and wave to me.
     “Welcome aboard, captain.” The voice over the intercom was Gallagher’s. Most voices you can’t recognize over an intercom, but Gallagher’s is different. No intercom can cover that particular tonal quality. How he’d gotten that far that quick I didn’t know; but I did know that he was there. Yet—you couldn’t even have walked that distance on the skin of a metal ship in a suit with electret shoes, much less on the surface of a glacier with whatever crampers or ice-locks he’d dreamed up to keep him from drifting off the berg.
     “Hi,” I said weakly. “About ready to give up this foolishness?” It was too late to change my rationale now, though it did sound a little silly, what with the efficiency with which he’d got his stuff secured and gotten ready to go to work.
     “I rather thought you’d come because you were ready to give up your foolishness,” he replied. “Have they got the Starfire back to its sluggish norm yet? Independent Spaceways, namely me, can use a good navigator. glad you’re volunteering.”
     He’d hit the nail on the head about that retuning, and I could feel myself getting red. I was glad I was in a vac suit and he couldn’t see it. I kept my voice calm and merely said, “You look to be handling the initial stages okay. But maybe you’ve had some second thoughts.”

     I dropped from the shuttlebug. As my feet touched the ice, I was surprised to find that the electret shoes of my own suit gripped it quite satisfactorily. Somehow I hacln’t expected the electrostatic field to work on ice, even though I could see Gallagher standing right there waiting for me with no gripping problem.
     He laughed and led me to the bubble dome, and as we unhelmeted in the airlock, I put my foot in my mouth again. “Who’s working on the far side of your berg?” I asked. “I saw somebody in a vac suit there as I came in. I thought you were alone.”
     He didn’t answer at once, just opened the inner airlock door. And there, leading off from the far side of the dome, was a yawning shaft going straight down into the ice, with a shuttlebug hanging in its mouth as though it were just as logical to use one inside a ship as out.

     “Just me and my bugs, captain,” he said grinning.
     “Bugs?” I glanced sideways at Gallagher and then back at the hold. Then: “Shuttlebugs I understand. But tunnels like that? Why, it would take a man a month to dig a tunnel like that through a berg like this.
     He nodded solemnly. “Aye, and you’re right, captain. But I didn’t mean just shuttlebugs. Most of the cargo ye landed me here with was bugs of one kind and another.” He pointed to a large, odd-looking circular metallic device lying to one side against a wall of the dome. “There’s one of the bigger ones there.”
     I walked over and looked at the thing. It had a rim which I judged would just fit inside the tunnel; and in the center of the rim a rotating nose with a screw thread on it. About one turn every two centimeters, I decided. I looked more closely at the rim and saw that there were ridges so that if it were passing through ice it could slide easily forward, but could not turn readily. The rim itself seemed to be of two different materials, with a leading edge of metal, and a ten-centimeter-long trailing section of plastic that matched the shape, including the grooves.
     “Quite a fancy gadget,” I said. “But—how can a thing like this drill through ice? That nose with the screw thread on it doesn’t look very sharp, and certainly there aren’t any teeth here.” I pointed to the surface between the protruding screw nose and the rim.
     “Careful. It’s hot,” Gallagher said—and the idea of the machine clicked into my mind as an operating device. The surface was sensibly hot. The screw would be heated, too; and if you turned the thing nose-first against a piece of ice and gave it a shove, it could probably melt its way rapidly in and then get hold and keep on going. A sievelike mesh that formed the metallic surface between the rim and the spinner screw would take in water, I realized.
     “Clever,” I said. “Is it self-programming?”
     “Pretty much so. It’s got maybe the brains of a mouse. That’s what I call it. An ice mouse.”

     “What does it do with the water?” I asked.
     “Just kicks it out the back into the tunnel. I have to pump it from there. But I’ve smaller ones as well, and they make nice little water pipes for wherever I want to program them to go, so the pumping’s not all that much of a problem.”
     “And you pump the water out to those radiator surfaces for refreezing?” I asked. “How did you manage to move radiators like that around anyhow? Or, for that matter, where did you get them? I don’t recall having landed anything as heavy as a radiator here.”
     “Well, now. Which question first? The radiators were part of the equipment you landed, believe it or not. But they’re not heavy. They’re very lightweight plastic, and high-temperature stuff at that. It’s amazing how much more heat you can reject at four or five hundred degrees than you can from a low-temperature surface. And since it ’s the difference you’re working with, it makes good sense to have high-temperature radiators where the only energy dumped is by black-box radiation.
     “To answer the first question last, though,” Gallagher went on, “the water is not pumped directly into the radiators. If it were, that’s where it would freeze up. Actually, the refrigeration system is a little more complicated than that. But you’re right; that water is refrozen after it’s pumped where I want it. I scoop it out here and freeze it there. In a few weeks, I’ll have this berg balanced out and hollowed out and set up just the way I want it.”

     I had to admire the system, but I guess I was jealous enough I had to disparage it, too. So, since it was at least chilly if not downright cold in that dome, I shivered as obviously as possible as I said, “It would seem that you’ve picked a pretty well air-conditioned environment, but aren’t you afraid that the constant cold will get to you?”
     Gallagher grinned and motioned me to the tunnel leading down. “Come on in,” he said. “This dome is sort of chilly. It’s acting as my airlock right now, but I’ll probably replace it with a more conventional airlock sooner or later."
     It was a weird sensation, taking a shuttlebug through a tunnel where I could have reached both walls by simply outstretching my arms. The smooth, glistening ridges that had been left behind by Gallagher’s ice mouse as it formed the tunnel were as regularly milled and precise as the machine that had made them. But it seemed to me that we ’d not gone nearly halfway through when the shuttlebug paused and I swung myself off into a short corridor at right angles.
     This one wasn’t milled. It wasn’t ice, for that matter. And there was proper decking for the soles of my boots to get a better hold. Of course there was no gravity, but I automatically assumed that Gallagher would take care of that— and in the not-too-distant future, at the rate he was going.

     “Your hotheaded ice mice,” I asked. “Can they be suitably programmed for making the necessary spin-and-balance tubing for a zero M-I spin-grav system?”
     “Sure. Ought to have that operating now”— Gallagher glanced at his wrist chronometer— “in another four or five hours. The mice are much busier than I am.”
     “But with water rushing around in ice tubes, won’t you have some tendency for the tubes to melt and distort?”
     “Melt? Sure they will. Except that the water will be brine, and a bit colder than the melting point of ice, so they won’t melt very fast. Distort? Well, maybe. Under some conditions of acceleration, the tubes will probably distort a bit, but mostly, since the fluid in the spin tubes goes in one direction and the ship goes in. the other, the net friction and thrust is radial to the spin. There shouldn’t be much distortion. The tubes will simply gradually work themselves right on out towardithe surface. But long before that happens, I’ll make a new tube inside. Anything a mouse can do once, he can do all over again. Like I said, they?re going to be busier than I am”
     “But won’t each spin tube leave a hollow place behind it?” I asked.
     “Nope. You see right above each spin tube there ’s a much smaller and much colder tube. So the tubes will plate back on the top what they lose on the bottom.”
     I paused for a minute and thought that one out. Up, of course, was toward the center of the ship, since we were talking about spin gravity. And down would be toward the outside of the ship.

     ;“Wait a minute, though. Will that tube on top move out along with the other, larger tube? Or, for that matter, why couldn’t "you put the cold tube underneath the spin tube to prevent the spin tube from wearing out?”
     “One at a time.” Gallagher waved me on through the bulkhead and into a comfortable cabin. “No matter how cold I made the ice, when ice is under pressure, it will melt. Obviously, the spin tubes will be under pressure. Therefore they would gradually melt even if they were kept much colder than would be reasonably efficient. So actually it’s much simpler to allow the tube to melt and move itself out, say, three times the distance of its own diameter. Then simply make a new tube in the part it started from. Actually, it’ll probably be more complicated that that. There’ll be one tube being made and another being filled in while a third, somewhere in between them is operating to keep the spin going.”
     I could follow that much, but I had a feeling that if I let Gallagher go on, there would be more and more complications added. I could even visualize part of it. The necessary static balance tanks in which the level of water could be changed as other weights—like people—moved around inside the ship and tended to shift the spin-center according to their own positions. But it was really a very standard sort of thing operationally, and I could have drawn a blueprint for it from the memory of my own ship.

     “Okay, but just one more point,” I finally decided. “This cabin is nice and warm and insulated no doubt. But it does have mass and it will walk, just like that spin tube. What do you plan to do about that?”
     “Now you’re getting the picture, Harald!” Gallagher broke into a huge grin. “There’s no such thing as static stability in a malleable ship. And ice is one of the most malleable media you could ask to work with. Actually, this cabin is built with a hot head, something like that the mice use. You turn everything off and let it sink, it would sink right on out through the ice and get spun off into space, once we got spin gravity going. But its rate of sinking won’t be very fast, when you consider the square area of floor and the actual mass involved—as a matter of fact, it will float and move toward the inside. But we can do something about it whether it floats or sinks. It’s merely a matter of melting a little bit of the ice around the room and then repositioning it by hydrostatic pressure. If I want to move a cabin to the other side of the ship, I can do it in two or three days and scarcely disturb a thing in the process.”
     I shook my head in awe. The idea of floating cabins around in a ship to make new layouts at will was a bit much for a by-the-book captain and engineer such as myself.
     Then Gallagher capped it by summing the whole thing into a nutshell that spelled not only the difference between our ships, but between ourselves and what we represented.
     “You see,” he said, and his damned voice wasn’t even sarcastic, “you’re used to thinking in terms of static stability—forms that keep their shape by being rigid; forms that can’t change because any major change destroys them.
     “My glacier,” he went on, and his voice was warm and loving, “she can change and adapt and grow and evolve. She has dynamic stability, and that’s quite a different thing.”

(ed note: Gallagher hidden meaning is that the megacorporation that has a stranglehold on interstellar trade also has static stability, and cannot change because a major change would destroy the corporation. Gallagher's free trader company has dynamic stability, so it can change and adapt and grow and evolve.)

     That Gallagher. I cursed the day I’d met him, as I orbited back to Altura and my spick-and-span ship with all its properly latest gadgets and technological advances incorporated as they were developed. I’d never own my own ship, but by the gods, I told myself, I captained a good one! And when my time was run, as it runs fast in the spaceways, l’d have the cash to buy a small farm and settle down on any planet that I chose where they were accepting colonists.
     And there was Gallagher, as though he were mocking me, with an old Antolaric drive and probably the finest engineering talent on the starlanes, using it to make an old hunk of ice into a makeshift ship that would be the laughingstock of the spaceways.

     Take those radiator units—made of black plastic which could be turned black side toward the darker portions of space as radiators; or, in event of an emergency, toward the local sun as power collectors. The back surface was a silvery, metalized reflector, air-spaced to insulate the radiators from the icy surface to which they were attached.
     And they were attached, as were the mooring tubes I’d worried about—quite effectively attached with a gadget he called a hothead bug. It was a combination electric motor with a double-acting screw thread and a very hot nose; similar to his ice mice, but designed as an anchor. Place the thing on the ice and start it moving, it would burrow itself in like a tiny animal; and the screw thread with which it drove itself would remain in the tube. behind it, so it could be run in and back out again if you wished. Or it could simply run in pulling a cable behind it and stay there for as long as you liked.
     He had small ones for anchoring and big ones —the ice mice—for corridors; and extensive ones with which he was riddling the surface of the ship, creating small-bore tubing in the ice to be used for such things as circulating the cooling brine to maintain the frozen surfaces, and to carry off the melted water to be refrozen where it was needed.
     And the drive itself, that I’d seen stanchioned back there like a pushberger. Hell, he’d just positioned it so that the hydrostatic force of its driving would melt it right inside the ship to where he wanted it.

     And Gallagher was wasting that engineering genius on a hunk of ice! Why, the man could work up to captain, would he abide the rules!

     But my own ship didn’t look as pretty as she used to look, and though I still saw to it that my men went portside only in threes, I took to going in alone, myself, in full uniform, and be damned to the risk.
     The whole thing worried me, and it worried me more as the months passed and the tales began to be traded from bar to bar.
     At first Gallagher and his glacier were a roar of laughter that swept the spaceways. But it was more than just a roar of laughter. The spaceways had their first independent shipper, and it was a proud thing, there under the stars.

From GALLAGHER'S GLACIER by Walt Richmond and Leigh Richmond (1979)


In 2010 Brian S. McConnell and Alex Tolley developed the Spacecoach concept and published it in a paper Reference Design for a Simple, Durable and Refuelable Interplanetary Spacecraft. This relatively low cost orbit-to-orbit spacecraft would be admirably suited for wagon trains in space. They could actually open up the solar system to pioneers if coupled with a low-cost surface-to-orbit transportation system such as a laser launcher. But McConnell and Tolley think the mass could be brought down enough to bring it within the boost capacity of, say a SpaceX Falcon 9 or Falcon 9 Heavy.

The basic premise of the spacecoach is to create a fully reusable orbit-to-orbit spacecraft that uses water and waste gases from crew consumables as its primary propellant.

So the design makes the consumables mass do double duty: first as life support for the crew, then as propellant. This drastically lowers the mass of the spacecraft, thus lowering the cost.

This also removes the incentive to install an expensive and cantankerous closed ecological life support system. Yes, supplies for a multiple year journey take up a lot of mass, but since it can be lumped under the heading of "propellant" it does not matter as much.

The water component of the consumables can do triple or quadruple duty. Before it is used as propellant, it can also serve as radiation shielding, supplemental debris shielding (as pykrete), and thermal regulation. In his simulation boardgame High Frontier developer Philip Eklund called water "the most valuable substance in the universe", and he was not kidding.

The spacecoach is also mostly constructed of water, in the form of pykrete. Very little metal is to be used. Actually it is very much like the composite ship from The Martian Way

The spacecoach will have sizable solar cell arrays used to power some species of electric rocket. There is some research underway to determine which of the many electric propulsion systems works best with water.

Ion drives, VASIMR, and helicon double layer rockets won't work because they are electricity hogs. They need to be fed by a nuclear reactor or equivalent, solar cells are too weak. Besides the insane price tag on a reactor and the ugly mass penalty, governments will be dubious about entrusting Maw and Paw Kettle with nuclear energy. They do have wonderful exhaust velocities, but the price is just too blasted high. Some won't even work with water as propellant.

Hall Effect Thrusters, Microwave Electrothermal Thruster (MET), and Electrodeless Lorentz Force Thruster (ELF) are much more suitable. They require much more modest amounts of electricity. Their exhaust velocities are weaker than the electricity hogs, but they are still much more potent than puny chemical rockets. These drives are also simpler to fabricate (i.e., cheaper, more reliable, lightweight, durable, and easily serviced). They can be clustered into arrays in order to increase the thrust. Electricity hog drives start interfering with each other if you cluster them.

The MET is especially simple. It isn't much more than a metal tube with a microwave magnetron attached. No moving parts either. It is sort of like a cross between a rocket engine and a microwave oven.

Current research shows a MET using water propellant can crank out a good 8,800 m/s exhaust velocity (Isp 900 sec) while an ELF can do about 16,700 m/s (Isp 1,700 sec). A Hall Effect thruster using water could theoretically do 29,000 m/s (3,000 sec) but researchers are still trying to figure out how to adapt them to water propellant.

For back-of-the-envelope calculations figure a spacecoach engine can do from 7,900 m/s to 20,000 m/s exhaust velocity (Isp 800 sec to 2000 sec). Compare this with chemical rocket's pathetic 4,400 m/s (450 sec).

20,000 m/s might not be quite enough to manage a trip to Ceres (10.593° inclination to ecliptic means a lot of delta V is needed), but the performance may be improved with more research.

The low thrust also minimizes the need for mass-expensive structural members.

McConnell and Tolley do have several design competitions open.


In December 2010, the Journal of the British Interplanetary Society published our peer reviewed paper, "Reference Design For A Simple, Durable and Refuelable Interplanetary Spacecraft".

The paper describes a ship made mostly of water, powered by microwave engines, that will be capable of reaching destinations throughout the solar system, at just 1/10th to 1/100th the cost of conventional chemical rockets.

The system described in the paper is based entirely on existing technologies that have already been flight tested or are well under development, and is feasible with present day technology and Earth launch platforms to low orbit.

These ships, in addition to being cheaper to build, will be fully reusable, and will be mostly organic structures that will be far more comfortable than conventional capsule designs, and more like a scaled down version of Gerard K O'Neil's proposed space colonies than a metal ship.

We're coining the term spacecoach to describe these ships, a reference to the prairie schooners of the Old West.

We hope you enjoy this site and share it with your friends and colleagues.

Brian S McConnell
Alexander M Tolley
From the introduction at the Spacecoach website

The covered wagon or prairie schooner is one of the iconic images of the 19th century westward migration of the American pioneers. The wagon was simple in construction, very rugged, and repairable. They were powered most often by oxen that lived on the food and water found along the trail. The cost of a wagon, oxen and supplies was about 6 months of family wages.

In 2009 my colleague Brian McConnell and I were thinking about how to open up the exploration of space in an analogous way to the opening up of the American West during the 19th century pioneering era. We were looking for an approach that, like the covered wagon, was affordable, relatively low tech, provided safety in the case of emergencies and the space environment, could “live off the land” for propulsion like oxen, and preferably was reusable so that costs could be amortised over a number of flights.

What follows is a description of the “spacecoach” from the perspective of a new crew member making a first visit to the ship that will be on a Phobos return mission.

Our transfer vehicle docked gently with the Martian Queen airlock. On approach, the Martian Queen resolved into 4 fat sausages, linked end to end. On either side, from bow to stern, were solar PV arrays, partially unfurled. She looked like no spaceship seen since the dawn of the space age.. There was no gleaming metal hull, and she was devoid of all the encrustations of antennae and dishes of those earlier ships. Neither were there any signs of fuel tanks holding liquid cryofuels. Instead, the hull looked dull and somewhat like an old blimp, those non-rigid airships of the early 20th century. The only sign of exterior equipment were those solar PV panels. These were lightweight, moderate performance thin film arrays, extended out on booms to face the sun and drink her rays to power the ship. They looked more like square rigged sails as they fluttered every so gently in the tenuous atmosphere remaining at her orbit.

I knew from the briefing that the Martian Queen needed about 160KW of power, requiring about 800 m2 of arrays at Mars orbit. There was also talk of the next generation “spacecoaches” replacing the PV panels with lightweight rectennas, to convert microwave beams from the orbital transmitters. Most crews didn’t trust that idea yet, but adding a lightweight rectenna was considered a good idea to back up the PVs and also compensate for the lower intensity of sunlight as the newer ships were about to explore Jupiter space. So this was the Martian Queen, the “spacecoach” that would be my home, about to make her 2nd voyage to Phobos.

Following my crew mate Vicki, I passed through the airlock and entered a large space, nearly 60 m3 in volume, shaped like a large cylinder. The interior diameter was about 4.5 meters, about the same as the mothballed Orion I’d seen back at the Cape museum.. But with a length of 10 meters, the volume was 3x larger. The Martian Queen was composed of 4 modules, providing over 200 m3 of full sea level atmosphere pressurized volume, about 2/3rds that of the old Mir space station. Touching the inner skin of the hull it felt flexible, and slightly cool to the touch. A few light taps and the resonant sounds confirmed that there was liquid behind the skin.

Vicki answered my unspoken question about the liquid in the hull. Water was sandwiched between several layers of impermeable Kevlar in the hull. The primary, and ultimately end, use of all the water was for propellant. The spacoach had originally been folded for launch in a standard Falcon 9 fairing. Each module, without any propellant, weighed just 4 tonnes including payload. This was very little and reduced the deadweight mass of the ship. Once in orbit, the interior had been inflated and the hull filled with water. Most of that water had been launched by dumb, low cost boosters, but some was being supplied from extra-terrestrial resources. Supplies from the lunar south pole were becoming increasingly available as Chevron-Petrobras’ Shackleton base was building up mining production. Exploratory vessels were also initiating operations on asteroids, with 24 Themis looking promising with confirmed surface water. In a few decades, it was expected that all water would be supplied from extra-terrestrial sources.

“Why do you put all the water in the hull, rather than in separate tanks?” I asked.

Vicki explained that the water had a number of roles, not just as propellant. The primary reason was radiation protection. The water acted as a good radiation shield, with a halving of the radiation flux with every 18 cm (half value thickness of 18 cm). Starting with about 25 cm of water in the hull, the radiation level inside the module was just 40 percent of that striking the hull (0.5 ^ (25/18) = 0.38 = 40%). In the event of a major solar flare, the crew could also redirect the water to an interior tube to provide the best radiation shielding for the crew (storm cellar). It looked like that space could get very cozy for the crew, but better than suffering radiation burns.

But it didn’t end there. Micrometeoroids are a rare, but important hazard. The water acted as a shield, absorbing the energy of these grains and preventing penetration inside the hull. The tiny holes in the outer layers quickly heal too. The outer layers of water could be allowed to freeze, trapping a dense forest of fine fibers between the 2 outer fabric layers. This made a strong material, very much like pykrete [1] that offered a stiff outer hull to protect against larger impacts. At Earth’s 1 AU from the sun, reflective foils deployed over the hull allowed passive freezing of the outer layers providing both protection and a large heat sink for the engines.

A noticeable side effect of the hull architecture was the silence. There are no clicks and bangs from thermal heating stresses. Nor did the sunward side of the interior feel noticeably warmer. Thus the water was going to offer very good thermal control of the interior, with pumps in the hull circulating the water providing dynamic thermal control.

Vicki indicated that I should follow her forward to another module. This included the kitchen and dining space. There was a freezer of dried food packages that was being organized by Pieter. Enough for a long trip with a fair variety of meals.

“You seem to have ordered a lot of Boeuf Bourguignon”, joked Pieter.

I wondered when the taste of Boeuf Bourguignon would become rather tiresome after some months. Perhaps more spicy meals like curries would have been more appropriate. I noted that the water supply for rehydrating the food and drinks was connected to the hull too. Of course, I reminded myself, the hull was a huge reservoir of water, effectively inexhaustible are far as the crew was concerned, at least on the outward bound flight.

The facilities were oriented so that “down” was towards the end of the module. This was because during cruise the Martian Queen was going to be rotated, providing some artificial gravity(tumbling pigeon). This made the flight much more comfortable and familiar. We could even eat off regular plates.

(Spacecraft is 40 meters long, 20 meters spin radius. Nausea limit is 3 rotations per minute. At that rate of spin gravity at nose and tail will be 1/5 g, fading to zero g at spin center.)

Vicki quickly showed me the crew quarters and bathroom in the next module. The inner skin of the hull had been moulded into shapes that could contain water. The baths and showers were also connected to the hull’s water supply. The clean water input was connected to heaters and pumps to the various faucets and shower heads. The grey water from the drains was routed to the main purifier and returned to the hull. I inquired how frequently I could take a shower? Once, twice even three times a week?

“As much as you like”, said Vicki. “There is ample water supply for a single pass through the purifier for all the crew to shower once or twice a day. If the crew is particularly extravagant, even this can be increased with greater recycling. Hygiene is a huge morale booster on these trips.”

The toilet was apparently a composting type, although suitably modified for space. This made sense. The nitrogen and phosphorus was going to be needed for the plants growing in the interior, as well as the Phobos base agricultural areas. Nitrogen and phosphorus were still valuable elements with no rich, off-Earth supplies available. Ducking back into the kitchen space, it was clear that much of the interior was given over to growing plants. They provided the needed psychological connection with Earth, helped recycle the CO2, and freshened the air, removing unpleasant volatiles. The stale, locker room smell of most spaceships was almost absent. Some plants were also growing some fresh foods. I could just imagine the value of a fresh tomato after 6 months of spaceflight!

Pulling ourselves back through the leafy interior of the modules, I looked for the engine compartment in the last module. The engines were not obvious on docking, and I wondered where they were. At the rear of the last module, an airlock was currently open, showing an enclosed space beyond. Inside, Hans, the engineer was taking apart one of the engines. He was removing a metal liner from the engine and replacing it with a fresh one. He handed the old one to me and said “carbon deposits”.

I looked closely and saw what he was talking about. Carbon deposition from contaminants in the water supply could build up in the engines, reducing performance. The engines were not much more complex than microwave ovens, although they were fitted with electric grids to further accelerate the microwave heated water plasma.

The exhaust exited via the rear, when the bay doors were opened. Now they were closed, allowing the shirt sleeve repair of the engines. I asked how frequent engine repairs were. Hans informed me that an engine needed some rework after 3—6 hours of operation. The microwave electrothermal engine performance had an Isp of about 800s, although the secondary electric grids could double that by drawing on reserve energy from the solar arrays. Vicki thanked Hans and we drifted back to the main module.

I was a little surprised at the lack of windows, but pleased that there were many flat screens where windows should have been. I looked “out” and saw that I had missed the vernier and maneuvering jets on the hull.

“How are these powered?” I asked Vicki.

Hydrogen Peroxide, H2O2” she replied.

“Where’s the fuel?”.

“There isn’t any yet. It’s made during the flight. Some of the water in the hull is tapped off, run through that off-the-shelf, standard unit over there. We store the peroxide in hull pockets to wait for the next use. The peroxide engines aren’t very efficient, having an Isp of about 160s, but they provide higher thrust than the main engines and can be used to boost the ship for a faster departure, or land the ship on low gravity worlds with orbital delta-Vs of 0.5 km/s or less. The peroxide has other uses too. It can be decomposed to provide oxygen [3] more quickly than the main ESS electrolyzers, act as an energy store for emergency power [4] and finally as an excellent bactericide to keep the interior clean and remove the bacterial slimes and molds that grow on the inner skin, often in difficult to reach spaces. And before you ask, yes, we have rotating cleaning duties on the Martian Queen.”

So the water in the hull fulfilled a range of uses, before being finally consumed as propellant. Major uses included bathing, direct consumption, rehydrating food, growing plants and, of course, the main oxygen supply. It was converted to peroxide for the high thrust engines, for energy storage and for another emergency O2 supply.

“Vicki, a quick mental calculation seems to come up short on the water requirement for the flight. Is what I see all that is needed?”

Vicki smiled: “The impact of using water as propellant on performance is significant. The total water budget for the trip is about 4 times the total mass of the ship and payload, compared to about 14 times for a conventional liquid hydrogen and LOX chemical rocket, primarily because of the higher Isp of the electrothermal engines. But the low hull mass and reduced consumables payload reduces the main mass of the the Martian Queen allowing a much smaller, more efficient spaceship. She is also a lot roomier, more comfortable and much safer. An Apollo 13 type accident would not be survivable in a conventional ship, but we have very large reserves of consumables and oxygen for the crew to survive until a rescue or the return trajectory was complete. In addition, even without water supplies at Phobos, the baseline mission cost to Phobos and return is on the order of a $100m dollars. That is why your institution can afford to pay for your slot on this mission. Reusability of the Martian Queen for multiple missions, fresh water at Phobos, and better performing solar panels and electric engines will eventually reduce that cost perhaps another order of magnitude.

I pondered that for a moment. While not a cheap solution for interplanetary travel, it put the cost well within the realm of the super-rich and wealthy institutions. A mere decade earlier, a simple lunar flyby and return in an adapted Soyuz craft was priced at around $100m per passenger by Space Adventures. Spaceflight was definitely getting cheaper and safer.

If interplanetary travel is initially based around the design concepts of water propellant craft, then the economics and infrastructure requirements will be dependent on available supplies of water already in space at suitable locations for fuel dumps. Bodies that may harbor economically useful quantities of accessible water include the moon (shadowed polar regions), water rich asteroids and dead comets. A tantalizing possibility is Ceres, that Dawn is expected to rendezvous with this year (2015). Ceres is expected to have prodigious quantities of frozen water, possibly even a subsurface ocean. A mining operation to extract pure water from the brew of ice and chemicals might offer the opportunity to open up the inner solar solar system. Once at Jupiter, the icy moons offer an almost inexhaustible supply of water.


1. Pykrete

2. Bigelow Aerospace B330

3. 47kg O2/1000 kg H2O2 (10%)

4. ~2 MJ, kg.

5. J E Brandenburg, J Kline and D Sullivan, “The microwave electro-thermal (MET) thruster using water vapor propellant,” Plasma Science, IEEE Transactions on (Volume:33, Issue:2) pp 776-782 (2005).

6. E. Wernimont, M. Ventura, G. Garboden and P. Mullens. “Past and Present Uses of Rocket Grade Hydrogen Peroxide

From SPACEWARD HO! by Alex Tolley (2015)

With manned missions to Mars in our thinking, both in government space agencies and the commercial sector, the challenge of providing adequate life support emerges as a key factor. We’re talking about a mission lasting about two years, as opposed to the relatively swift Apollo missions to the Moon (about two weeks). Discussing the matter in a new essay, Brian McConnell extends that to 800 days — after all, we need a margin in reserve.

Figure 5 kilograms per day per person for water, oxygen and food, assuming a crew of six. What you wind up with is 24,000 kilograms just for consumables. In terms of mass, we’re in the range of the International Space Station because of our need to keep these astronauts alive. McConnell, a software/electrical engineer based in San Francisco, has been working with Alex Tolley on the question of how we could turn most of these consumables into propellant. The idea is to deploy electric engines that use reclaimed water and waste gases to do the job.

With a nod to the transportation technologies that opened the American West, McConnell and Tolley have dubbed the idea a ‘Spacecoach.’ Centauri Dreams readers will remember Tolley’s Spaceward Ho! and McConnell’s A Stagecoach to the Stars, and the duo have also produced a book on the matter for Springer called A Design for a Reusable Water-Based Spacecraft Known as the Spacecoach. The new essay is a welcome addition to the literature on what appears to be a practical concept.

What fascinates me about the Spacecoach is that it enables us to begin building a space infrastructure that can extend past Mars to include the main asteroid belt. Using electric propulsion driven by a solar photovoltaic array, it achieves higher exhaust velocity than chemical rockets by a factor or ten, pulling much greater delta v from the same amount of propellant. Use water as propellant and you reduce the mass of the system by what McConnell estimates to be a factor of between 10 and 20. Huge reductions in cost follow.

Water as propellant? McConnell comments:

Electric propulsion is not a new technology, and has been used on many unmanned spacecraft. The idea is to use an external power source, typically a solar photovoltaic array, to drive an engine that uses an electrical or magnetic field to heat and accelerate a gas stream to great speed (tens of kilometers per second). Because these engines can achieve much higher exhaust velocity than chemical rockets, 10x or better, they can achieve greater change of velocity (delta v) using the same amount of propellant. This means they can venture to more ambitious destinations, carry more payload, or a combination of both. It also turns out these engines can also use a wide range of materials for propellant, including water.

We can imagine such ships as interplanetary vessels that never enter an atmosphere. They’re also completely reusable, allowing costs to be amortized, and their habitable areas are large inflatable structures that can be assembled in space. Thus we travel within a modular spacecraft using external landers and whatever other modules are required by the mission at hand. They’re also, compared to today’s chemical rocket payloads, a good deal safer:

The use of water and waste gases as propellant, besides reducing the mass of the system by a factor of ten or more, has enormous safety implications. 90% oxygen by mass, water can be used to generate oxygen via electrolysis, a simple process. By weight, it is comparable to lead as a radiation shielding material, so simply by placing water reservoirs around crew rest areas, the ship can reduce the crew’s radiation exposure several fold over the course of a mission. It is an excellent heat sink and can be used to regulate the temperature of the ship environment. The abundance of water also allows the life support system to be based on a one-pass or open loop design. Open loop systems will be much more reliable and basically maintenance free compared to a closed loop system such as what is used on the ISS. The abundance of water will also make the ships much more comfortable on a long journey.

Having just watched “To the Ends of the Earth,” a superb BBC story about a ship making a passage from Britain to Australia in the age of sail, the word ‘comfortable’ catches my eye. A Spacecoach is a large craft with huge solar arrays and the capability of being spun to generate artificial gravity, thus alleviating another major health hazard. Conditions are more Earth-like, and the abundance of water makes for what would otherwise seem absurd scenarios. Imagine taking a shower on a flight to Mars! The Spacecoach’s water management makes it possible.

McConnell believes that much of the mission architecture can be validated on Earth without the need to build a full-scale spacecraft, with the major emphasis on tuning up the electric propulsion technology that drives the concept. Using water, carbon dioxide and waste gases to test the engines can be the subject of an engineering competition, after which the engines could be tested in small satellites. Ultimately, manned Spacecoaches could be tested in cislunar space before their eventual deployment deeper into the Solar System.

McConnell calls the Spacecoach the basis of a ‘real world Starfleet,’ and adds this:

These ships will not be destination specific. They will be able to travel to destinations throughout the inner solar system, including cislunar space, Venus, Mars and with a large enough solar photovoltaic sail, to the Asteroid Belt and the dwarf planets Ceres and Vesta. They’ll be more like the Clipper ships of the past than the throwaway rocket + capsule design pattern we’ve all grown up with, and their component technologies can be upgraded with each outbound flight.

So if you haven’t acquainted yourself with McConnell and Tolley’s earlier work on the Spacecoach in these pages, have a look at Traveling to Mars? Just Add Water!, which recaps the basics of the design and outlines surface exploration strategies from orbiting Spacecoaches by telepresence. The key, though, is to mitigate the propellant issue by making consumables into propellant. Get that right and much else will follow, including the prospect of reliable, safe interplanetary transport of the kind needed to build a truly space-going civilization.

And after that? I’ve always believed that after sending instrumented interstellar probes, we’ll expand into regions outside our Solar System slowly, building space habitats as we go, mining local objects for needed materials. A functioning, space-going civilization builds out that infrastructure from within. It’s the ‘slow boat to Centauri’ scenario — our machines, enabled by artificial intelligence, get there first — but it’s a deep future that includes a human presence around other stars. When I see something as evidently practical as the Spacecoach, I get a renewed jolt of confidence that we at least know how to begin such a journey.

Water Wall

This is from Water Walls Life Support Architecture: 2012 NIAC Phase I Final Report (2012)

The idea here is to make a environmental control life support system (ECLSS) with a higher redundancy and reliability by making it passive, instead of active. Meaning instead of needing a blasted electrically-powered water-pump moving vital fluids around, use special membranes so that the vital fluids automatically seep in the proper direction. Fewer points of failure, fewer moving parts, no electricity needed, much more reliable.

The system harnesses the power of Forward Osmosis (FO), which mother nature has been using for the last 3.5 billion years since the first single-celled organism. Each unit has two compartments A and B, which share a wall made out of what they call a "semi-permeable membrane".

Compartment A contains contaminated water. Compartment B contains a solution (the "draw solution") which attracts water like a magnet using osmotic pressure. The contaminated water gets sucked through the semi-permeable membrane but leaves the contaminants behind (because the membrane won't let them through). The pure water (or purer water) winds up in compartment B with the draw solution and the contaminants remain in compartment A.

Since osmotic pressure is used there is no need for an electrical-powered water pump. It happens naturally just like a ball rolling downhill.

The research team noted that there already exists a commercial example of this: the X-Pack Water Filter System by Hydration Technology Innovations. You put nasty river water full of toxins and pathogens in compartment A and add a special sports-drink syrup into compartment B as draw solution. In about 12 hours compartment B will be filled with a refreshing sterile non-toxic sports-drink and all the horrible crap will be left behind in A.

So the research team realized that they could make a full ECLSS if they could develop some different types of forward osmosis bags and connect them together. They need bags that can do CO2 removal and O2 production (via algae), waste treatment for urine, waste treatment for wash water (graywater), waste treatment for solid wastes (blackwater), climate control, and contaminant control.

As a bonus cherry on top of the sundae, since all these will basically be bags of water, they can do double duty as habitat module radiation shielding.

The reliability comes from using lots of independent inexpensive disposable bags. The current system depends on driving an electromechanical water pump until it fails, then frantically trying to repair the blasted thing before all the toilets back up. Because the FO bags are cheap and low mass, they can be considered disposable, the spacecraft brings along crates of them with the other life support consumables. Because each bag uses forward osmosis as a built-in pump, there is no single point of failure. When one bag or cluster of bags, or integrated module of bags uses up their capacity, you switch the water line to the next units in sequence. The used bags can be cleaned, filled, and reused. Alternatively they can be stuffed somewhere in the habitat module to augment the radiation shielding.

This might work well as an affordable life support system for a cheap Maw and Paw TransHab habitat module. May or may not be useful in a SpaceCoach.

Kuck Mosquito

RocketCat sez

This thing looks really stupid, but it could be the key to opening up the entire freaking solar system. Orbital propellant depots will make space travel affordable, and these water Mosquitos are just the thing to keep the depots topped off.

Kuck Mosquito
ΔV5,600 m/s
Specific Power4.8 kW/kg
(4,840 W/kg)
Thrust Power484 megawatts
PropulsionH2-O2 Chemical
Specific Impulse450 s
Exhaust Velocity4,400 m/s
Wet Mass350,000 kg
Dry Mass100,000 kg
Mass Ratio3.5
Mass Flow49 kg/s
Thrust220,000 newtons
Initial Acceleration0.06 g
Payload100,000 kg
Length12.4 m
Diameter12.4 m

Kuck Mosquitoes were invented by David Kuck. They are robot mining/tanker vehicles designed to mine valuable water from icy dormant comets or D-type asteroids and deliver it to an orbital propellant depot.

They arrive at the target body and use thermal lances to anchor themselves. They drill through the rocky outer layer, inject steam to melt the ice, and suck out the water. The drill can cope with rocky layers of 20 meters or less of thickness.

When the 1,000 cubic meter collection bag is full, some of the water is electrolyzed into hydrogen and oxygen fuel for the rocket engine (in an ideal world the bag would only have to be 350 cubic meters, but the water is going to have lots of mud, cuttings, and other non-water debris).

The 5,600 m/s delta-V is enough to travel between the surface of Deimos and LEO in 270 days, either way. 250 metric tons of H2-O2 fuel, 100 metric tons of water payload, about 0.3 metric tons of drills and pumping equipment, and an unknown amount of mass for the chemical motor and power source (probably solar cells or an RTG).

100 metric tons of water in LEO is like money in the bank. Water is one of the most useful substance in space. And even though it is coming 227,000,000 kilometers from Deimo instead of 160 kilometers from Terra, it is a heck of a lot cheaper.

Naturally pressuring the interior of an asteroid with live steam runs the risk of catastrophic fracture or explosion, but that's why this is being done by a robot instead of by human beings.

In the first image, ignore the "40 tonne water bag" label. That image is from a wargame where 40 metric tons was the arbitrary modular tank size.

There are more details here.

Water Truck

Water Truck
Specific Power9.6 kW/kg
PropulsionSolid core NTR
Specific Impulse198 s
Exhaust Velocity1,942 m/s
Wet Mass123,000 kg
Dry Mass30,400 kg
Mass Ratio4.1
Total ΔV2,740 m/s
Total Propellant92,600 kg
Boost Propellant75,700 kg
Landing Propellant16,900 kg
Boost ΔV1,859 m/s
Landing ΔV881 m/s
Mass Flow155 kg/s
Thrust301,000 newtons
Initial Acceleration0.25 g
Payload20,000 kg
Tank Length8.5 m
Total Length11.9 m
Diameter3.38 m
Structural Mass
Guidance Package0.45 tons
Tank1.6 tons
Thrust Structure
and Feed Lines
0.91 tons
Primary and
Secondary Structure
1.82 tons
Landing System0.68 tons
25% Growth Factor2.09 tons
Reactor1.82 tons
Turbopumps and
Rocket Nozzles
0.23 tons
Reaction Control
0.68 tons
Total10.3 tons

The Lunar ice water truck is a robot propellant tanker design by Anthony Zuppero. Its mission is to boost 20 metric tons of valuable water from lunar polar ice mines into a 100 km Low Lunar Orbit (LLO) cheaply and repeatably. It is estimated to be capable of delivering 3,840 metric tons of water into LLO per year.

This design uses a nuclear thermal rocket with currently available materials, and using water as propellant (a nuclear-heated steam rocket or NSR) instead of liquid hydrogen). This limits it to a specific impulse below 200 seconds which is pretty weak. However, numerous authors have shown that a NSR could deliver 10 and 100 times more payload per launched hardware than a H2-O2 chemical rocket or a NTR using liquid hydrogen. This is despite the fact that the chemical and NTR have much higher specific impulses. NSR work best when [1] the reactor can only be low energy, [2] there are abundant and cheap supplies of water propellant, and [3] mission delta-Vs are below 6,500 m/s.

The original article describes the water extraction subsystem at the lunar pole. It is a small reactor capable of melting 112.6 metric tons of ice into water (92.6 metric tons propellant + 20 metric tons payload) in about 45 hours. This will allow the water truck to make 192 launches per year, delivering a total of 3,840 metric tons of water per year.

Since the water truck is lifting off under the 0.17 g lunar gravity, its acceleration must be higher than that or it will just vibrate on the launch pad while steam-cleaning it. The design has a starting acceleration of 0.25 g (about 1.5 times lunar gravity).

The landing gear can fold so the water truck will fit in the Space Shuttle landing bay, but under ordinary use it is fixed. The guidance package mass includes radiation shielding. In addition, the guidance package is on the water truck's nose, to get as far as possible away from the reactor. The thrust structure and feed lines support the tank and anchor the reactor. The 25% growth factor is to accommodate future design changes without having to re-design the rest of the spacecraft. The reaction control nozzles perform thrust vector control. They take up more mass than a gimbaled engine, but by the same token they are not a maintenance nightmare and additional point of failure.

The reactor supplies about 120 kilowatts to the tank in order to prevent the water from freezing. The reactor mass is 50% more than minimum. The lift-off burn is about 20 minutes durationa and consumes 0.7 kg of Uranium 235.

Water Ship

Water Ship
Specific Power31 W/kg
PropulsionSolid core NTR
Specific Impulse190 s
Exhaust Velocity1,860 m/s
Wet Mass299,030,000 kg
Water tank mass25,000 kg
Nuclear Engine+
structural mass
123,000 kg
Sans Payload Mass148,000 kg
Payload mass50,000,000 kg
Dry Mass50,148,000 kg
Mass Ratio5.96
ΔV[1] 802 m/s
[2] 1280 m/s
[3] 752 m/s
Mass Flow[1,2] 903 kg/s
[3] 2,684 kg/s
Thrust[1,2] 1,680 kiloNewtons
[1,2] 4,990 kiloNewtons
Nozzle Power[1,2] 4.9 gigawatts
[3] 1.6 gigawatts
Engine Power[1,2] 12.1 gigawatts
[3] 4.1 gigawatts
Initial Acceleration[1] 0.0006 g
[2] 0.0009 g
[3] 0.005 g
Payload50,000,000 kg
Length85 m
Diameter85 m

The Water Ship is a robot propellant tanker design by Anthony Zuppero. Its mission is to deliver 50,000 metric tons of valuable water from the Martian moon Deimos to orbital propellant depots in Low Earth Orbit (LEO) cheaply and repeatably. It is not much more than a huge water bladder perched on a NERVA rocket engine. It might have integral water mining equipment as does the Kuck Mosquito, or it might depend upon a seperate Deimos ice mine.

Mass of water bladder is 25 metric tons (rated for no more than 0.005 g). Mass of nuclear thermal rocket plus strutural mass is 123 metric tons (struture includes computers, navigation equipment, and everything else). Mass without payload is 25 + 123 = 148 metric tons. Payload is 50,000 metric tons of water. Dry mass is 148 + 50,000 = 50,148 metric tons. Propellant mass is 248,882 metric tons. Wet mass is 50,148 + 248,882 = 299,030 metric tons.

At Deimos, only about 4.55 megawatts will be needed to melt 299,000 metric tons of ice into water (50,000 tons for payload + 249,000 tons for propellant). The engine nuclear reactor can supply that with no problem. The water must be distilled, because mud or dissolved salts will do serious damage to the engine nuclear reactor. By "serious damage" I mean things like clogging the heat-exchanger channels to cause a reactor meltdown, or impure steam eroding the reactor element cladding resulting in live radioactive Uranium 235 spraying in the exhaust plume.

Nuclear thermal rocket was designed to be a very conservative 100 megawatts per ton of engine. Engine will have a peak power of 12,142 Megawatts (for stage [1] and [2]). This works out to a modest engine temperature of 800° Celsius, and a pathetic but reliable specific impulse of 190 seconds. A NERVA could probably handle 300 megawatts per ton of engine, but the designer wanted to err on the side of caution. This will require much more water propellant, but there is no lack of water at Deimos.

This design uses a nuclear thermal rocket using water as propellant (a nuclear-heated steam rocket or NSR) instead of liquid hydrogen). This limits it to a specific impulse below 200 seconds which is pretty weak. However, numerous authors have shown that a NSR could deliver 10 and 100 times more payload per launched hardware than a H2-O2 chemical rocket or a NTR using liquid hydrogen. This is despite the fact that the chemical and NTR have much higher specific impulses. NSR work best when [1] the reactor can only be low energy, [2] there are abundant and cheap supplies of water propellant, and [3] mission delta-Vs are below 6,500 m/s.

It is true that electrolyzing the water into hydrogen and oxygen then burning it in a chemical rocket will get you a much better specific impulse of 450 seconds. But then you need the energy to electrolyze the water, and equipment to handle cryogenic liquids. These are just more things to go wrong.

In the table, [1], [2], and [3] refer to different segments of the journey from Deimos to LEO.

  • [1] Start at Deimos. 497 m/s burn into Highly Eccentric Mars Orbit (HEMO). At apoapsis, 305 m/s burn into Low Mars Orbit (LMO)
  • [2] At LMO periapsis, 1,280 m/s burn using the Oberth Effect to inject the water ship into Mars-Earth Hohman transfer orbit
  • [3] 270 days later at LEO periapsis, 752 m/s burn using the Oberth Effect to capture the water ship into Highly HEEO
  • [x] Water ship does several aerobrakes until it reaches an orbital propellant depot in LEO

Total thrust time is about 10 hours.

Water ship's propellant has 15,137 metric tons extra as a safety margin. When it arrives, hopefully some of this will be available. It will take 322 metric tons of propellant for the empty water ship to travel from HEEO to Deimos, or 1,992 metric tons to travel from LEO to Deimos. Plus 0.139 gigawatts of engine power and 10 hours of thrust time.

Traveling from Deimos to LEO will consume about 12.7 kg of Uranium 235. Given the fact that Hohmann launch windows from Mars to Earth only occur every two years, the fuel in the engine nuclear reactor will probably last the better part of a century before it has to be replaced. The engine will be obsolete long before then.

For more details, refer to the original article.

Hydrogen Ice Ship

This is a variant using frozen hydrogen instead of H2O. The attraction is using the frozen hydrogen to do double-duty as structural members as well as propellant. This allows a welcome increase in the spacecraft mass-ratio that is something wonderful.


0.0 Abstract

     There are three types of spacecraft considered in this paper in which the primary concern is the engineering of hydrogen ice. The first is an unmanned fusion-powered probe, in which hydrogen ice acts as structural material, radiation shielding, and fuel source. The second is an approach to on-orbit refueling with propellant transfer via hydrogen ice, and subsequent slushification. The third is an array of self-contained hydrogen ice satellites with embedded cryogenic avionics and detonation wave propulsion. Each of these innovative concepts depends on the behavior of hydrogen ice; hence a thermal analysis of sublimation-cooled hydrogen ice spheres is provided.

1.0 Why Iceships?

     Unmanned interstellar probes powered by nuclear fusion require a minimum deadweight ratio (fraction of non-payload mass remaining after all fuel is expended) and minimum molecular weight of exhaust material. An innovative way to achieve this is for the fuel and the structural components of a fusion probe to be one and the same.

     Among contenders, beryllium (molecular weight 8) is rather difficult to vaporize, leaving the prime choices as either water ice (molecular weight 18) or lithium (molecular weight 6) stiffened by boron (molecular weight 11) or carbon (molecular weight 12) fibers, being vaporized, ionized, and expelled as reaction mass until no structural components remain besides the payload and now-useless engine.

     In the last case, recent analysis by J. B. Stephens et. al. at NASA-JPL suggests that even hydrogen ice (molecular weight 2 ) can be stiffened by admixture of fibrous or particulate material far beyond its normal pliability — about the same as butter. Hydrogen ice can also be adequately protected against sublimation by very modest insulation. A one meter radius sphere of hydrogen ice, insulated by a centimeter of low-density hydrogen ice fluff and one centimeter of layered reflector, can last ten years in Earth orbit.

     What are the structural limits of fiber-stiffened water ice, hydrogen ice, and lithium? Is it preferable to filter out the fibers, adding them to the deadweight, or to add engine weight to allow them to also be ionized and added to the exhaust? And, in the case of a water-ice fusion spacecraft, can we legitimately refer to this as the ultimate steamship?

2.0 Hydrogen Iceship: Detailed Examination

     This section of the paper concentrates on the hydrogen ice spacecraft concept, and consists of an introduction, thermal analysis, experimental results, conclusions, and suggestions for future research.

     Much of this analysis was contributed by James Salvail, of SETS, Inc., Honolulu.

     Rather than having astronauts perform extravehicular activity to chip off chunks of hydrogen ice for fuel, we visualize a spacecraft made of a structural cluster of hydrogen ice spheres which can be robotically detached, one at a time as needed, and melted or slushified in a conventional fuel tank.

2.1 Hydrogen Iceship: Introduction

     A hydrogen ice spaceship can be modelled as a cluster of concentric metal spheres each of which has hydrogen ice filling the spaces between its spherical surfaces. Most of the mass of the spacecraft is composed of these spheres, with the mass of the engine, avionics, payload, and so on comprising a much smaller fraction. The spheres are designed to provide some structural capability and to maintain fuel in solid form until needed (at which point they are liquefied for propellant usage).

     Concentric spheres are connected to each other by at least two rods made of a material that has very low thermal conductivity, such as hard rubber. This is necessary so that the spheres above the instantaneous level of the subliming ice surface do not move relative to each other. The outer shells are made of a highly reflective material, such as aluminized (more easily ionized in propulsion: lithium-ized) mylar, thick enough to provide reasonable structural integrity. The inner spheres are made of the same materials, but much thinner (<<0.1 cm), as they are merely radiation shields.

     The radiation shields and outer hulls must contain enough sufficiently sized holes or pores so that sublimed hydrogen molecules are quickly lost into space. The evacuated spaces between the slowly receding ice surface and the outer hulls thus have negligable gaseous heat conduction because the gas is very rarified. Gas flux is small enough (barring close flyby of the sun, nuclear explosions, or laser heating) that heat convection is also negligible. Under the listed abnormal operating conditions, gaseous conduction/convection would still be much smaller than radiative heat transfer. The effects of varying sphere radii, radiation shield number/spacing, outer hull albedo, and external environment are investigated to optimize the design for cost, size, and lifetime.

2.2 Hydrogen Iceship: Thermal Analysis

     Thermal analysis consists of temperature calculations for outer hull, radiation shields, fixed radii from centers, and (crucially) at ice surfaces. Hull and shields are sufficiently thin and heat conductive as to be effectively isothermal through their thicknesses.

     The energy balance at the outer hull consists of incoming solar radiation, emitted radiation from both sides, incoming radiation from the adjacent lower surface, and downward gaseous heat conduction. The two sides of the outer hull have, in general, different albedos and emissivities (if, for example, painted black externally for stealth). These effects are described by:

     Where Em is the emissivity of the natural metallic surface, Eb is the emissivity of the outer surface (possibly black), unsubscripted E is the emissivity of the adjacent lower surface. If the lower adjacent surface is a radiation shield, then E=Em . If the lower adjacent surface is the ice surface, then E=Eh the emissivity of the ice. Am, is the albedo of the natural metallic surface. T is temperature, with subscripts i and j denoting depth and time. fb is a geometric factor accounting for the smaller area of the adjacent inner surface. Sb is the Stefan-Boltzmann constant. Sc is the solar constant at 1 AU (Astronomical Unit). Kg is the gaseous thermal conductivity of hydrogen. r is the radial coordinate (from the center of the ice sphere). R is the heliocentric distance in AUs. The factor 4 in the right hand solar insolation term reflects the assumption of rapid rotation. Constant values are given in section 2.3 . This equation, and a related one for the moving ice surface (with an energy balance including upward radiation from the ice surface, downward radiation from the adjacent metal surface, heat conduction into the ice, and the latent heat energy due to sublimation) are the basis for the results of section 2.3 .

where dr is the distance between adjacent surfaces. A similar factor which accounts for the larger area of an adjacent outer surface is given by:

The energy balance at inner surfaces above the level of the receding ice includes emitted radiation from both sides, incoming radiation from adjacent surfaces above and below, and downward heat conduction. This is described by the equation:

In our model, the space above the ice is gas so rarified that conduction is negligible. Solving for temperature (as a function time) in closed form gives:

At the ice surface, the energy balance includes upward radiation from the ice surface, downward radiation from the adjacent metal surface, heat conduction into the ice, and the latent heat energy due to ice sublimation. This is given by the equation :

where Kh is the thermal conductivity of hydrogen ice, Hs is the latent heat of hydrogen ice, Ah is the albedo of the ice, B is the vapor pressure constant, M is the molecular weight of hydrogen, and Ru is the universal gas constant. This equation is one of the boundary conditions for the ice domain. Again, the derivative of T with respect to r is actually a partial derivative.

For the interior of the hydrogen ice, the heat diffusion equation (in spherical coordinates) is:

where Dh is hydrogen ice density, C is hydrogen ice specific heat, and t is time. For the sake of our computer simulation, the derivatives of the two previous equations are approximated as finite difference equations:

where x is a parameter that takes into account the possibility of unequal distances between nodes (x=1 when nodes are equidistant).

If we define an additional parameter y as:

where dt is the discrete time step, we can solve for Ti,j:

Since the boundary condition at the center of the sphere is:

or, in finite difference form upon solving for Ti,j:

We now have four equations for Ti,j, which form a system of nonlinear algebraic equations which are solved iteratively in the simulations to provide a temperature profile through the hydrogen ice sphere.

The flux due to sublimation of the hydrogen ice is:

where Th is the temperature of the ice surface.

Finally, we derive the distance of the ice surface from the sphere's outer surface as follows. The mass loss during a time interval t* is:

where r is the radius of the residual ice sphere at the beginning of the time interval and h is the thickness of ice sublimed during the interval. we expand this to:

We can also express mass loss during the time interval t* as:

where ravg is the average value of r during t*, and can be approximated as:

Which is substituted into the later expression for mass loss to give:

Equating this with the first expression for mass loss, and rearranging terms, gives:

We can numerically solve the cubic for h. If the time interval is small enough (h<<r) then we can neglect the term containing h3 , allowing the explicit solution:

and therefore the instantaneous distance of the receding hydrogen ice surface from the outer surface of the sphere is:

where Hj-1 is the distance at the beginning of the time interval.

The results of the computer simulation, and the values of the constants used in the above equations, are given in Section 2.3, below.

2.3 Hydrogen Iceship: Computer Simulation Results

     Computer simulation based on the preceding analysis calculated temperature at outer surface, radiation shields, surfaces and interior of the hydrogen ice. Ice surface temperature allowed derivation of hydrogen gas flux and radial position of the receding ice surface as a function of time, and thereby deriving hydrogen ice lifetime. Various runs determined the effects of radiation shields, outer albedo, and outer hull radius, in normal conditions and in a simulated nuclear blast. Kirchoff's law was assumed for metallic and ice surfaces. Parameter values are as listed below:

AVapor pressure constant6.17 × 109 dynes/cm2
BVapor pressure constant149.44°K
AmAlbedo of metal0.95
AhAlbedo of hydrogen ice0.65
EmEmissivity of metal0.05
EhEmissivity of hydrogen ice0.35
ChSpecific heat of hydrogen ice2.7 × 107 erg/g-°K
DhDensity of hydrogen ice7.06 × 10-2g/cm3
KhThermal conductivity of ice1 × 107 ergs/cm-s-°K
HsLatent heat of hydrogen ice6.2 × 109 ergs/g
ScSolar constant at 1 AU1.3928 × 106 ergs/cm2-s
TiInitial temperature of ice5°K
MMolecular weight of hydrogen2.0 g/g-mole
SbStephan-Boltzmann constant5.6 × 10-5ergs/cm2-s-°K
RuUniversal gas constant8.315 × 107 ergs/mole-°K

     First, a 1 meter radius sphere with 50 radiation shields spaced 2 centimeters apart and natural metallic surface was simulated. The ice remained nearly isothermal at the initial temperature of 5°K, with a negligible temperature gradient and a near-constant mass flux of 17.8 nanograms/cm2-sec. The outer hull remained at a temperature of 236°K at 1 AU from the sun. After a simulated 10 years, the sphere had shrunk to 21 cm in radius, and the total lifetime was approximately 12 years.

     Reducing the radiation shields from 50 to 10 had no effect. Painting the outer surface black (albedo = 0 for stealth) gave a tripled mass flux of 53.8 nanograms/cm2-sec, a surface temperature of 5.2°K, and a reduced lifetime of 4.2 years.

     At 0.1 AU from the sun a 50-shield 1 meter shiny sphere stays at 5.81°K with a mass flux of 1.06 micrograms/cm2-sec, and a lifetime of 75 days. With 10 shields, a 1 meter shiny sphere stays at 6.39°K, with a mass flux of 10.5 micrograms/cm2-sec, and a lifetime of 35 days. Hence radiation shields are important for larger thermal loads, such as would occur if the hydrogen iceship mission began with a gravity assist swingby close to the sun.

     The thermal effects of nearby nuclear detonation were simulated as a temporary change in heliocentric distance from 1.0 AU to 0.01 AU (where the radiative equilibrium temperature for a black body is 2808°K) for 20 seconds. If the outer metallic coat doesn't melt at the maximum temperature attained (2361°K), then the hydrogen ice adjacent to the outer surface peaks at 8.73°K, with a gas flux of 4.7 milligrams/cm2-sec, decreasing after 10 minutes to 5.85°K (ten shields) or 5.79°K (fifty shields), at which time the ice has receded 2.5 cm.

     All other things being equal, the lifetime of a hydrogen ice sphere was found to be directly proportional to the first power of the the initial radius. Thus, a 2 meter radius sphere has a 24 year lifetime at 1 AU, and 2 years at 0.1 AU. For deep space missions, loss becomes rather small for spheres several meters in radius.

2.4 Hydrogen Iceship: Summary of Concepts

     The greatest advantage for a hydrogen ice spacecraft is obtained if the craft is an unmanned monolithic composite solid cryogen with embedded insulation and superconducting avionics. As disclosed by J. Stephens at JPL (who generated the original concepts in 1984 and 1985, while in communication with this author), the primary intellectual properties for patent purposes are:

  1. Ice embedded insulation
  2. Vapor cooled insulation
  3. Isomer conversion catalyst integral with insulation (activated carbon)
  4. IR photon reflective and vapor conductive insulation (variable mesh cloth multi-layer insulation)
  5. Vapor cast crystalline hydrogen ice using nuclear magnetic resonance heating of non-crystalline ice
  6. Self-forming filamentary insulation from dispersed particles in the ice that cohere due to ice cleaning

     The attributes of the primary intellectual properties are:

  1. Unitized design; ice is the cryogen, structure, propellant, shielding, absorber, power source, window, and insulation support during launch
  2. Superconducting temperature cryostat (<5°K for Hydrogen)
  3. Self-insulating solid cryogen
  4. Long lifetime in earth orbit
  5. Low cost materials (<$10/lb)
  6. Low cost fabrication (casting process)
  7. Low launch cost (withstand high acceleration forces)
  8. Low cost operation (efficient superconducting solid-state system)
  9. Acoustically quiet (no moving parts) so good for very accurate optics or interferometry
  10. Thermally stable (large thermal capacity well insulated)
  11. High density ice vapor cast and used at same temperature to avoid shrink stresses in the insulation and other components embedded in the ice

     The ancillary intellectual properties enabled by the primary concepts are:

  1. Vapor cooled refractory insulation
  2. Neutron absorbing cryogen (Hydrogen)
  3. Microwave absorbing ice/insulation
  4. Microwave reflecting ice/insulation

     The advantages of the ancillary concepts are:

  1. Laser tough shielding
  2. Neutron tough shielding
  3. Neutral and charged particle beam tough shielding
  4. Radar stealth
  5. Superconducting phased array radar

     Concepts enabled by Cryostat primary and secondary concepts are:

  1. Propulsion and electric power systems:
    1. Solar powered ion rocket and superconducting magnet power generator and storage system
    2. Magnetohydrodynamic detonation wave ion rocket and superconducting magnet power generator and storage system (detonate layers of solid oxygen alternated with solid hydrogen)
  2. Guidance and control:
    1. Superconducting computer
    2. Superconducting gyroscope
    3. Superconducting magnet attitude control
    4. Superconducting radio and antenna
  3. Launch forces resistant structure:
    1. fiber reinforced composite ice
  4. Remote sensing synersensory systems in phased arrays in Cryostats orbiting in formation:
    1. Synthetic aperture superconducting phased array radar
    2. Synthetic aperture superconducting phased SQUID array Magnetic Anomaly Detection
    3. Synthetic aperture superconducting phased SQUID array Gravimeter
    4. Synthetic aperture superconducting phased array Altimeter
    5. Blue-Green synthetic aperture superconducting phased array lidar
    6. Thermal IR telescope spectrometer

     This astonishingly rich set of concepts of Jim Stephens is only moderately challenged by demands of the interplanetary or interstellar regime, as opposed to the near-Earth applications originally envisioned.

     Individual hydrogen ice spheres can be orbited by small boosters, and later assembled into a large spacecraft. Solid hydrogen is inherently safer than liquid hydrogen. The spheres can have embedded avionics, providing distributed redundant capability for the spacecraft at superconducting temperatures. Once assembled, the low accelerations typical of an ion, fission, or fusion propulsion would not endanger the inherently low tensile strength of hydrogen ice as a structural material. The hydrogen ice spheres would be between the crew (or radiation-sensitive instrumentation) and the nuclear propulsion, providing neutron-absorbant shielding at no extra cost.

     Space exploration applications include:

  1. Sungrazer
  2. Outer planet explorer
  3. 1000 AU mission (TAU)
  4. Subterranean radar mapping of planets
  5. Manned Mars Mission
  6. Propellant transfer and storage for Space Station refueling depot (see 3.4)

2.5 Solar Hydrogen Iceship

     Hydrogen ice can be a propellant other than by the already-stated means of slushification and combustion with oxygen, detonation-wave combustion with oxygen ice, or by fusion.

     Hydrogen ice can be the basis of a very efficient solar heated spacecraft. As researched at Rockwell, it was first realized that energy was saved in skipping liquefaction of hydrogen ice and oxygen ice. It is more efficient to burn the vapor subliming from hydrogen and oxygen ice (kept in separate tanks). Sublimation rates can be raised by heating with off-axis solar reflectors. Solar heating becomes more efficient if the hydrogen ice has embedded carbon black, to increase light absorption.

     Even more efficient is a scheme to use solar heating to ionize hydrogen, and keep the ions trapped at the focus with a superconducting magnetic bottle. This process can be enhanced by doping the hydrogen with a thermal electron emitter such as LaB6.

     Combining these various concepts, we are led to the following. Hydrogen ice propellant, laced with carbon black and lanthanum boride, is heated by solar reflectors. The sunlight passing through the partially reflecting surface is absorbed by solar photovoltaic cells. Carbon-blackened hydrogen is heated, and the embedded thermal electron emitter provides ionization. Hydrogen ions are trapped by a superconducting magnetic bottle. The solar cells generate current, which is used to power an ion accelerator. Hydrogen ions and electrons are thrust away by the ion engine, and the spacecraft moves forward by reaction. We note that stray hydrogen ions curving back to the spacecraft can do very little damage, whereas conventional metal ion engines (cesium or mercury) run the risk of plating and electrical short-circuit.

2.6 Hydrogen Iceship: Future Research

     Future areas of systems analysis for the hydrogen iceship include:

  1. Comparisons of fiber-stiffened water ice, carbon dioxide, lithium, or other alternatives to hydrogen ice
  2. Experimental determination of strength, stiffness, etc. for hydrogen ice with various fiber compositions (boron, carbon)
  3. Structural design optimization for various types of propulsion systems
  4. Exploration of the concept of detonation wave propulsion/attitude control with alternating layers of hydrogen ice and oxygen ice
  5. Sensor capabilities of phased arrays of embedded cryogenic detectors in a fleet of coorbiting iceships
  6. Relativistic kinematics of multi-staged interstellar iceships
From HYDROGEN ICE SPACECRAFT by Jonathan Post (1990)

Type Notes

(ed note: this system assumes the presence of propellant depots. Otherwise the the delta-V budgets will have to be more or less doubled)

I imagine 3 types of vehicles for space development.

The yellow vehicles have a nearly 10 km/sec delta-V budget and a thick atmosphere to contend with. It is possible these will always be multi-stage expendable vehicles. (ed note: Space Ferry)

The red vehicles move between locations in different orbits. They need no landing mechanism, no thermal protection or ablation shields, parachutes, etc. They have delta V budgets between 4 and 3 km/sec. It is my belief such vehicles could be single stage, reusable vehicles. (ed note: Orbit-to-Orbit)

The green vehicles (lander/ascent vehicles) move between orbital locations and a surface of a substantial body, but not as substantial as earth. Their delta V budget is around 5 km/sec. I believe these vehicles could also be single stage, reusable vehicles. (ed note: Airless Lander)

It would take some investment to build infrastructure to maintain and supply the propellant depots pictured here. Wouldn't it be cheaper to just send ships directly from Earth to Mars? That depends. If your goal is flags and footprints sortie missions, disposable mega rockets are the way to go. But if you wanted genuine development of Mars, it would take many, many trips. If infrastructure could enable these trips to be done with smaller, reusable vehicles, the infrastructure would return the investment many times over.

Specialized Ship Types

Broadly speaking, a spacecraft has multiple uses. Just change the payload. However, for certain jobs the spacecraft will require drastic optimization.

Yes, the line between general ship types and specialized ship types is a bit fuzzy. I did the best I could.

Blockade Runner
Much like a covert smuggler ship. Except instead of trying to sneak past a few putt-putt custom boats, it is trying to sneak past a blockading enemy military battlefleet armed to the teeth who is currently investing the planet. So blockade runners might tend to have better acceleration, weapons, and defenses than you'd find in your average covert smuggler ship.
Originally a small boat used to ferry supplies to ships moored away from the shore. In a spaceship context, I suppose "shore" could mean either a space station or a ground based spaceport. And "moored away from" could mean "not docked to the space station" or "in orbit around the planet the spaceport is located on." The name comes from the combination of the Dutch word for a canoe"boomschuit" ("boom" meaning "tree"), and "boat".
Cargo Vessel
      A cargo ship or freighter ship is a merchant ship that carries cargo, goods, and materials from one port to another. Unlike tramp freighters these ships are cargo liners, operating as "common carriers" and calling a regularly published schedule of ports.
     A tanker is a specialized cargo vessel. Cargo vessels Cargo holds and a remarkably large mass ratio. Common carriers use standardized cargo containers. Bulk Cargo ships carry cargo not packaged in cargo containers, such as food grains or unprocessed ore.
Clan Ship
Huge ship used as a space-going home for tribes of space nomads. Kind of like a faster-than-light generational starship, but with no fixed destination. They often support themselves by interstellar trading.
You only find these in science fiction universes that have faster-than-light starships but no faster-than-light radios. These are ultra-optimized ships that are designed for one single purpose: to deliver messages between stars as fast as possible. Some do not even have normal-space propulsion systems.
Customs Border Patrol Boat
Cutter-class ships used by the spacial branch of the planetary customs agency. They check out incoming spacecraft: collecting tariffs, halting or confiscating contraband, and apprehending smugglers. High acceleration because the bootlegger ships will often be running away. Extensive sensor suites because bootlegger ships will be doing their darnedest to be invisible. Armed because you never know when desperate bootleggers decide to open fire.
A type of small boat, often carried or towed by a larger vessel for use as a lifeboat or tender. A dinghy's main use is for transfers from larger boats, especially when the larger boat cannot dock at a suitably-sized port or marina. The term is a loanword from the Bengali ḍiṅgi, Urdu ḍīngī, and Hindi ḍieṁgī.
Spacecraft designed to insert army units into a hot landing zone on a planet you are invading. "Hot" means "full of enemy troops shooting at you."
Free Trader Ship
     Tramp freighter spacecraft, generally owned by the free trader crew. Generally the ship is also the crew's only home.
     Sometimes they try their hand at being amateur trade pioneers, which is a dangerous task for the professionals and insanely dangerous for the amateurs. If they try, they will have rudimentary planetary exploration gear.
A type of flat-bottomed barge used to transfer goods and passengers to and from moored ships. Can either have its own dedicated rocket engines or be moved by small maneuverable harbour tugs called "lighter tugs".
Merchant Ship
A merchant vessel, trading vessel, or merchantman transport cargo and/or passengers for hire. They can be either cargo ships or tramp freighters
Orbit Guard Vessel
Vessels used by the space-going version of the Coast Guard. Their ships have rescue equipment, ship grappling gear, ship repair supplies space taxis, space pods, and a propulsion bus with extra delta V.
Passenger Ships
If the level of technology has reached the point of casual spaceflight and if transit times are reasonable, there may arise a type of spacecraft whose cargo is mainly human beings. If the trip is one day or overnight it is a Ferry. If the trip is weeks to months it is a Space Liner. If it carries both cargo and people it is a Cargo-Cum-Liner. If it is a large ship used for vacationing rather than transport it is a Cruise Ship. If the cargo is one singularly talented human being, it may be a Diplomatic ship or Secret Agent ship. If the cargo is large numbers of miliary soldiers it is a Troop Carrier. If the cargo is large numbers of workers on long term contract being transported to a work site it is a Worker Hauler.
As a ship's boat, the pinnace is a light boat carried aboard merchant and war vessels to serve as a tender. In modern parlance, "pinnace" has come to mean an auxiliary vessel that does not fit under the "launch" or "lifeboat" definitions. A pinnace would ferry passengers and mail, communicate between vessels, scout to sound anchorages, convey water and provisions, or carry armed sailors for boarding expeditions. Other uses include lightweight smuggling vessels or raiders.
Pirate Corsair
A warship barely strong enough to defeat an unarmed merchant ship, with enough cargo space to carry off the cream of the looted booty from the merchant. Manned by the futuristic equivalent of one-eyed peg-legged brigands waving cutlasses and saying "AAArrrr.." a lot.
Planetary Exploration Vessel
Exploration scout ship used by the Survey Service to discover and evaluate potential colonizable planets, to boldy go where no one has gone before. First-In scout ships do the discovery of promising planets, while also being alert for dangerous anomalies. Exploration ships do in-depth studies of planets the first-in scouts think are worthy of a closer look. The ships are equipped with extensive remote sensing suites on the lookout for biosignatures, technosignatures, and necrosignatures. They carry space ferries, airless landers, or other landers to transport survey crews to the surface. They also carry mobile bases/labs and exploration flitters.
See Pirate Corsair. Except ship is also equipped with a Letter of Marque and Reprisal.
A warship disguised as a helpless merchant ship, hoping to lure a pirate ship to its doom.
Revolt Ships
Enforcement warships an interstellar empire stations over member planets which are in danger of rebelling and trying to secede from the empire. Some revolt ships are optimised for orbital bombardment. May operate in association with space superiority platforms.
Safari Ship
This is a science fictional ship that turns up occasionally in some novels. This is a ship for wealthy but impotent individuals who try to get it up by exploring strange new worlds, seeking out new life, shooting them, and hanging the poor innocent animal's head on the wall as a trophy. For those impotent individuals who cannot afford their own ship, there are safari services for hire. For a reasonable price they will transport you and other customers to a wilderness planet to participate in a prefabricated big game hunt. For example: Star Hunter by Andre Norton, or the Animal class Safari Ship from Traveller Adventure 10: Safari Ship.
Ship's tender
     A boat, or a larger ship used to service or support other boats or ships, generally by transporting people or supplies to and from shore or another ship. Smaller boats may also have tenders, usually called dinghies.
     On cruise ships, lifeboat tenders do double duty, serving as tenders in day-to-day activities, but fully equipped to act as lifeboats in an emergency. They may at first glance appear to be regular lifeboats; but they are usually larger and better-equipped. Before these ships were mass-produced, the main way to board a larger ship (mainly ocean liners) was to board a passenger tender. Passenger tenders remained based at their ports of registry.
Spaceguard ships
Ships used by the spaceguard services of all spacefaring nations. They keep a close watch to prevent unauthorized alterations in the orbits of potential civilization-wreaking asteroids. They will be equipped with large telescope arrays to monitor asteroid trajectories, and nuclear detonation detectors since nukes can be use for orbital alteration. They will have equipment to alter the orbits of dangerous asteroids, such as casaba howitzers and mass-driver propulsion. These can also be used as weapons, in case the asteroids still contain the evil villains who nudged the rock in the first place.
Space Patrol Ships
Semi-warships used by the Space Patrol. Depending upon the planetary government the patrol will have one or more of the following jobs: police, coast guard, border patrol, pirate fighters, spacecraft safety inspectors, and customs agents.
Smuggler Ships
     These are for entrepreneurs trying to move contraband goods past the Customs agents.
     Overt smuggler ships are designed to look exactly like a run-of-the-mill merchant ship, but equipped with secret compartments for contraband that is elaborately sensor-hardened to hide from custom agent hand-held scanners. Overt smuggler ships openly land at the planetary spaceport and try to act innocent.
     Covert smuggler ships try to sneak past the orbiting custom ships and secretly land at a hidden rendezvous. They rely upon a drastically reduced sensor signature, and the stealth provided from the bulk of the planet.
A tanker is a freigher designed to carry liquids or gas in bulk. In space the liquids are commonly liquified propellant. They have extra propellant tanks and a remarkably large mass ratios.
Tramp Freighter
A merchant cargo ship that does NOT have a fixed schedule or published published itinerary/ports-of-call, as opposed to cargo lines. Instead they trade on the spot market.
These are military logistics ships use to transport space army soldiers to combat zones. They mostly are huge habitat modules
Tugboats are slow but powerful spacecraft used to slowly but accurately move larger spacecraft and bulk cargo to and from orbital spaceports. They have ship grappling equipment, push plates, and an over-sized high-thrust propulsion bus.
     Military combat ships.
     A warship's payload section can include anti-spacecraft weapons, orbital bombardment weapons (for revolt suppression type spacecraft as well), weapon mounts, weapon control stations, combat information center, armor, point defense, weapon heat radiators and heat sinks, and anything else that can be used to mission-kill enemy spacecraft.
     I have an entire page devoted to the theory and practice of warship design.
Zoo ship
This is a science fictional ship that turns up occasionally in some novels. It travels from planet to planet, capturing examples of exotic alien critters, storing them in cages that recreate their normal environment, and eventually transporting the lot of them to some large zoological research station. For example: Hiding Place by Poul Anderson and The Soul Eater by Mike Resnick.

(ed note: Our heroes are on the run from the Attercops space barbarians. Their starship is damaged, and won't make it to the safety of the planet Freya. It is known that there are several uncontacted alien species in the sector who have starships. Their only hope is to find an aliens ship and convince them to take them to Freya.

They find an alien ship and overhaul it. It won't talk to them. Upon forcing entry they discover it is apparently a zoo ship, containing alien critters from many planets. Unfortunately the alien crew is hiding in cages with the critters. The alien's only contact with humans were the barbaric Attercops. Our heroes have to figure out which of the critters are actually the alien crew, and enlist their help to get to the planet Freya before the Attercop fleet finds and kills them all.)

      "Well?" snapped the merchant peevishly.
     Torrance cleared his throat. His voice sounded unfamiliar and faraway to him. "I think you'd better come have a look, sir."
     "You found the crew, wherever the sputtering hell they holed up? What are they like? What kind of ship is this we've gotten us, ha?"
     Torrance chose to answer the last question first. "It seems to be an interstellar animal collector's transport vessel. The main hold is full of cages—environmentally controlled compartments, I should say—with the damnedest assortment of creatures I've ever seen outside Luna City Zoo."
     "So what the pox is that to me? Where is the collector himself, and his fig-plucking friends?"
     "Well, sir." Torrance gulped. "We're pretty sure by now, they're hiding from us. Among all the other animals."
     "They're afraid of us," decided Torrance. "And they're not running back toward the Adderkop sun. Which two facts indicate they're not Adderkops themselves, but do have reason to be scared of strangers." He nodded, rather grimly, for during the preliminary investigations he had inspected a few backward planets which the bandit nation had visited.

     The main hold comprised almost half the volume of the great ship. A corridor below, a catwalk above, ran through a double row of two-decker cubicles. These numbered ninety-six, and were identical. Each was about five meters on a side, with adjustable fluorescent plates in the ceiling and a springy, presumably inert plastic on the floor. Shelves and parallel bars ran along the side walls, for the benefit of animals that liked jumping or climbing. The rear wall was connected to well-shielded machines; Yamamura didn't dare tamper with these, but said they obviously regulated atmosphere, temperature, gravity, sanitation, and other environmental factors within each "cage." The front wall, facing on corridor and catwalk, was transparent. It held a stout air lock, almost as high as the cubicle itself, motorized but controlled by simple wheels inside and out. Only a few compartments were empty.

     The humans had not strung fluoros in this hold, for it wasn't necessary. Torrance and Van Rijn walked through shadows, among monsters; the simulated light of a dozen different suns streamed around them: red, orange, yellow, greenish, and harsh electric blue.

     A thing like a giant shark, save that tendrils fluttered about its head, swam in a water-filled cubicle among fronded seaweeds. Next to it was a cageful of tiny flying reptiles, their scales aglitter in prismatic hues, weaving and dodging through the air. On the opposite side, four mammals crouched among yellow mists: beautiful creatures, the size of a bear, vividly tiger-striped, walking mostly on all fours but occasionally standing up; then you noticed the retractable claws between stubby fingers, and the carnivore jaws on the massive heads. Farther on the humans passed half a dozen sleek red beasts like six-legged otters, frolicking in a tank of water provided for them. The environmental machines must have decided this was their feeding time, for a hopper spewed chunks of proteinaceous material into a trough and the animals lolloped over to rip it with their fangs.

     "Automatic feeding," Torrance observed. "I think probably the food is synthesized on the spot, according to the specifications of each individual species as determined by biochemical methods. For the crew, also. At least, we haven't found anything like a galley."
     Van Rijn shuddered. "Nothing but synthetics? Not even a little glass Genever before dinner?" He brightened. "Ha, maybe here we find a good new market. And until they learn the situation, we can charge them triple prices."
     "First," clipped Torrance, "we've got to find them."
     Yamamura stood near the middle of the hold, focusing a set of instruments on a certain cage. Jeri stood by, handing him what he asked for, plugging and unplugging at a small power-pack. Van Rijn hove into view. "What goes on, anyhows?" he asked.
     The chief engineer turned a patient brown face to him. "I've got the rest of the crew examining the ship in detail, sir," he said. "I'll join them as soon as I've gotten Freelady Kofoed trained at this particular job. She can handle the routine of it while the rest of us use our special skills to . . ." His words trailed off. He grinned ruefully. "To poke and prod gizmos we can't possibly understand in less than a month of work, with our limited research tools."
     "A month we have not got," said Van Rijn. "You are here checking conditions inside each individual cage?"
     "Yes, sir. They're metered, of course, but we can't read the meters, so we have to do the job ourselves. I've haywired this stuff together, to give an approximate value of gravity, atmospheric pressure and composition, temperature, illumination spectrum, and so forth. It's slow work, mostly because of all the arithmetic needed to turn the dial readings into such data. Luckily, we don't have to test every cubicle, or even most of them."
     "No," said Van Rijn. "Even to a union organizer, obvious this ship was never made by fishes or birds. In fact, some kind of hands is always necessary."
     "Or tentacles." Yamamura nodded at the compartment before him. The light within was dim red. Several black creatures could be seen walking restlessly about. They had stumpy-legged quadrupedal bodies, from which torsos rose, centaur-fashion, toward heads armored in some bony material. Below the faceless heads were six thick, ropy arms, set in triplets. Two of these ended in three boneless but probably strong fingers.
     "I suspect these are our coy friends," said Yamamura. "If so, we'll have a deuce of a time. They breathe hydrogen under high pressure and triple gravity, at a temperature of seventy below."
     "Are they the only ones who like that kind of weather?" asked Torrance.
     Yamamura gave him a sharp look. "I see what you're getting at, skipper. No, they aren't. In the course of putting this apparatus together and testing it, I've already found three other cubicles where conditions are similar. And in those, the animals are obviously just animals: snakes and so on, which couldn't possibly have built this ship."
     "But then these octopus-horses can't be the crew, can they?" asked Jeri timidly. "I mean, if the crew were collecting animals from other planets, they wouldn't take home animals along, would they?"
     "They might," said Van Rijn. "We have a cat and a couple parrots aboard the Hebe G.B., nie? Or, there are many planets with very similar conditions of the hydrogen sort, just like Earth and Freya are much-alike oxygen planets. So that proves nothings." He turned toward Yamamura, rather like a rotating globe himself. "But see here, even if the crew did pump out all the air before we boarded, why not check their reserve tanks? If we find air stored away just like these diddlers here are breathing . . ."

     "I thought of that," said Yamamura. "In fact, it was almost the first thing I told the men to look for. They've located nothing. I don't think they'll have any success, either. Because what they did find was an adjustable catalytic manifold. At least, it looks as if it should be, though we'd need days to find out for certain. Anyhow, my guess is that it renews exhausted air and acts as a chemosynthesizer to replace losses from a charge of simple inorganic compounds. The crew probably bled all the ship's air into space before we boarded. When we go away, if we do, they'll open the door of their particular cage a crack, so its air can trickle out. The environmental adjuster will automatically force the chemosynthesizer to replace this. Eventually the ship'll be full of enough of their kind of air for them to venture forth and adjust things more precisely." He shrugged. "That's assuming they even need to. Perhaps Earth-type conditions suit them perfectly well."

     He paused before a compartment. "I wonder . . ."
     The quadruped within was the size of an elephant, though with a more slender build indicating a lower gravity than Earth's. Its skin was green and faintly scaled, a ruff of hair along the back. The eyes with which it looked out were alert and enigmatic. It had an elephant-like trunk, terminating in a ring of pseudodactyls which must be as strong and sensitive as human fingers.
     "How much could a one-armed race accomplish?" mused Torrance. "About as much as we, I imagine, if not quite as easily. And sheer strength would compensate. That trunk could bend an iron bar."
     Van Rijn grunted and went past a cubicle of feathered ungulates. He stopped before the next one. "Now here are some beasts might do," he said. "We had one like them on Earth once. What they called it? Quintilla? No, gorilla. Or chimpanzee, better, of gorilla size."

     Torrance felt his heart thud. Two adjoining sections each held four animals of a kind which looked extremely hopeful. They were bipedal, short-legged and long-armed. Standing two meters tall, with a three-meter arm span, one of them could certainly operate that control console alone. The wrists, thick as a man's thighs, ended in proportionate hands, four-digited including a true thumb. The three-toed feet were specialized for walking, like man's feet. Their bodies were covered with brown fleece. Their heads were comparatively small, rising almost to a point, with massive snouts and beady eyes under cavernous brow ridges. As they wandered aimlessly about, Torrance saw that they were divided among males and females. On the sides of each neck he noticed two lumens closed by sphincters. The light upon them was the familiar yellowish-white of a Sol-type star.

     He forced himself to say, "I'm not sure. Those huge jaws must demand corresponding maxillary muscles, attaching to a ridge on top of the skull. Which'd restrict the cranial capacity."
     "Suppose they got brains in their bellies," said Van Rijn.
     "Well, some people do," murmured Torrance. As the merchant choked, he added in haste, "No, actually, sir, that's hardly believable. Neural paths would get too long, and so forth. Every animal I know of, if it has a central nervous system at all, keeps the brain close to the principal sense organs: which are usually located in the head. To be sure, a relatively small brain, within limits, doesn't mean these creatures are not intelligent. Their neurones might well be more efficient than ours."
     "Humph and hassenpfeffer!" said Van Rijn. "Might, might, might!" As they continued among strange shapes: "We can't go too much by atmosphere or light, either. If hiding, the crew could vary conditions quite a bit from their norm without hurting themselves. Gravity, too, by twenty or thirty percent."
     "I hope they breathe oxygen, though—Hoy!" Torrance stopped. After a moment, he realized what was so eerie about the several forms under the orange glow. They were chitinous-armored, not much bigger than a squarish military helmet and about the same shape. Four stumpy legs projected from beneath to carry them awkwardly about on taloned feet; also a pair of short tentacles ending in a bush of cilia. There was nothing special about them, as extra-Terrestrial animals go, except the two eyes which gazed from beneath each helmet: as large and somehow human as—well—the eyes of an octopus.
     "Turtles," snorted Van Rijn. "Armadillos at most."
     "There can't be any harm in letting Jer—Miss Kofoed check their environment too," said Torrance.
     "It can waste time."
     "I wonder what they eat. I don't see any mouths."
     "Those tentacles look like capillary suckers, I bet they are parasites, or overgrown leeches, or something else like one of my competitors. Come along."
     "What do we do after we've established which species could possibly be the crew?" asked Torrance. "Try to communicate with each in turn?"
     "Not much use, that. They hide because they don't want to communicate. Unless we can prove to them we are not Adderkops… But hard to see how."
     "Wait! Why'd they conceal themselves at all, if they've had contact with the Adderkops? It wouldn't work."

     "I think I tell you that, by damn," said Van Rijn. "To give them a name, let us call this unknown race the Eksers. So. The Eksers been traveling space for some time, but space is so big they never bumped into humans. Then the Adderkop nation arises, in this sector where humans never was before. The Eksers hear about this awful new species which has gotten into space also. They land on primitive planets where Adderkops have made raids, talk to natives, maybe plant automatic cameras where they think raids will soon come, maybe spy on Adderkop camps from afar or capture a lone Adderkop ship. So they know what humans look like, but not much else. They do not want humans to know about them, so they shun contact; they are not looking for trouble. Not before they are all prepared to fight a war, at least. Hell's sputtering griddles! Torrance, we have got to establish our bona fides with this crew, so they take us to Freya and afterward go tell their leaders all humans are not so bad as the slime-begotten Adderkops. Otherwise, maybe we wake up one day with some planets attacked by Eksers, and before the fighting ends, we have spent billions of credits!" He shook his fists in the air and bellowed like a wounded bull. "It is our duty to prevent this!"

     The search turned up one more possibility. Four organisms the length of a man and the build of thick-legged caterpillars dwelt under greenish light. Their bodies were dark blue, spotted with silver. A torso akin to that of the tentacled centauroids, but stockier, carried two true arms. The hands lacked thumbs, but six fingers arranged around a three-quarter circle could accomplish much the same things. Not that adequate hands prove effective intelligence; on Earth, not only simians but a number of reptiles and amphibia boast as much, even if man has the best, and man's apish ancestors were as well-equipped in this respect as we are today. However, the round flat-faced heads of these beings, the large bright eyes beneath feathery antennae of obscure function, the small jaws and delicate lips, all looked promising.

     By God, you've got to admire them, Torrance thought. Captured by beings whom they had every reason to think of as conscienceless monsters, the aliens had not taken the easy way out, the atomic explosion that would annihilate both crews. They might have, except for the chance of this being a zoo ship. But given a hope of survival, they snatched it, with an imaginative daring few humans could have matched. Now they sat in plain view, waiting for the monsters to depart—without wrecking their ship in mere spitefulness—or for a naval vessel of their own to rescue them. They had no means of knowing their captors were not Adderkops, or that this sector would soon be filled with Adderkop squadrons; the bandits rarely ventured even this close to Valhalla. Within the limits of available information, the aliens were acting with complete logic. But the nerve it took!

From HIDING PLACE by Poul Anderson (1961)

(ed note: this is from a solo-play tabletop boardgame where the player explores several star systems. The game is a sequel to The Wreck of the BSM Pandora, where an accident on the Zoo Ship temporarily renders the crew unconscious and releases all the alien critters.)


The Ares Corporation BSM Pandora is a standard long range cruiser, Titan class, specifically equipped to study new planetary systems and collect extraterrestrial lifeforms. Although the prototype BSM cruiser was originally designed in 2689 A.D., the first ship was not completed until 2753; the Pandora's hull was orginally laid down in 2773, but it was not launched until 2784 (the third BSM crusier to come off the line).

The Pandora uses the standard binary LRC design. The FTL module (70 × 28 × 26 meters) uses the module 31 FTL drive (Monopole Corp.). The STL module (46 × 27 × 26 meters) uses the model HB2 STL drive (FRG AG). The main computer is a Fuji 5500 (AMC Ltd.), with sub-system processors belonging to the Huron 7600 series (General Electric).

The Pandora's FTL drive gives the ship an almost limitless operational range; the standard tour of duty is ten years, thus limiting the ship to an effective operational range of 112 light years (34.35+ parsecs).

The standard BMS mission consists of two parts: first, a survey of planetary systems for potential human habitats (either G2 — G2.5 readily habitable or Geneva Treaty 2098, Section IIIA, Subsection 4 — Terraformible Class habitable), and second, the collection of extraterrestrial biological specimens for study aboard ship or later transfer to Biological Mission Control, Arestia City, Mars...


After sub-Titan shuttle safely docks with Titan-class cruiser, the following operational checklist will be adhered to in the transfer of specimens into the Stage area.

  1. All crew members will evacuate Stage area.
  2. ALL airlocks to Stage area will be secured.
  3. Collecbot will be activated.
  4. Collecbot will open specimen Store Space.
  5. Collecpod will move energy cage to Store Space lock.
  6. Environment differential will be adjusted to minimum between cage and Store Space.
  7. Collecbot will transfer specimen from cage to Store Space.
  8. Collecbot will secure Store Space.
  9. Collecbot will administer anti-tranq to specimine.
  10. Specimen will be allowed to waken. (Note: NO CREW MEMBER WILL BE ALLOWED TO ENTER STAGE AREA!)
  11. Specimen will be allowed to test Store Space.
  12. If all specification prove safe (see Securing Specimens), crew members will be allowed to enter Stage area.
  13. If specification proves safe, collecbot will tranquilize specimen and transfer it to hibernation chamber (see Hibernation Transfer).

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