• 

(ed note: in the year 2050, our heros are members of the Southwestern Rocket Society (SRS) fan club. The fans want to travel in space in the worst way, but civilians are not allowed to fly in their own ships.

On a field trip to Luna Louis' rocket junkyard they are stunned to find the space ship Absyrtis sitting in the lot. As it turns out that ship was Mr. Louis' last command when he was in the UN Space Force, and when the ship was decommissioned he managed to obtain it at scrap metal prices.

Club president Chubb Delany has an insane idea. He tells Mr. Louis that the club would love to refurbish the old ship, and fly it on a short hop to Luna. With Mr. Louis as captain.

Mr. Louis says if the club will promise that, he will give the ship to them free, along with any used rocket parts in the lot needed for the refurbishing.)

THE SPACE SHIP ABSYRTIS

UN Space Force interplanetary cruiser, missile launching, universal type, Argonaut Class

The space ship Absyrtis of the Argonaut Class saw twenty-two years of service as a ship of the UN Space Force line fleet, and an additional five years in support and reserve capacity. She was a member of the fleet which put down the Asgard Space Station Rebellion. After her modification to an express cargo vessel, she was instrumental in the sustenance of the outposts and colony on Venus. Subsequent modifications enabled her to serve the Jovian moons. She operated as a support ship in the Titan expedition to Saturn, but obsolescence forced her to confine her operations to the Earth-Luna area in which she served in many capacities until being mothballed and placed in circum-terrestrial orbit. She was finally returned to White Sands Spaceport, sealed, decommissioned, and left to stand for two years before being sold to a local salvage yard.

She was the first ship to bear the name and the last of her class to be decommissioned and removed from the Big Book. Her reliability earned for herself and her crews three ratings of excellence, two efficiency awards, a UN citation, numerous national commendations, and the International Astronautical Federation plaque in connection with her work in the Jovian moons area.

• Manufacturer: Hueco Spacecraft Inc., White Sands Spaceport, America, Terra.
• Commissioned: May 2018

---

     “Have you, now?” Louis said quizzically. “And how do you like the farce space flight is now?”
     “Farce?” Chubb echoed.
     “Farce, son. They’re too sloppy these days. It’s too easy. Automatic controls. Nuclear drives. There was a time when space flight was an art! Yes, sir An art! Not button pushing! Used to load her up with thermo-propellants, hit the firing button when the clock said so, and fly her by the seat of your pants and the astrostat! All the time wondering if she was going to blow! … That was space flight! Pilots, they call themselves! Bah! Bus drivers is what they arel” He settled back in his chair and jerked his thumb over his shoulder. “Now, in the good old days, it was different. Take the old Absyrtis back there on my lot …”
     The junk yard was old stuff to Chubb, but LeRoy was utterly amazed at the terrific amounts of junk of all types. As the old skipper led them out to where the Absyrtis towered seventy meters over the low sheds, the real estate man found himself making mental estimates of the combined worth of this desert land and the tremendous inventory on it. It was plain to see that Luna Louis was not a down-and-out old spacebum. “Captain, there seems to be a little bit of everything here. How’d you come by it all?”
     “Ships are scrapped all the time, mate,” Louis replied.
     “Why? Do they wear out?”
     “No, sir! They just get obsolete,,and it becomes cheaper to build a new ship than to modify the old one,” Luna Louis explained. “The Bureau of Space Commerce has some pretty strict rules about the condition of space craft; when a ship reaches a certain age, they usually down-check it on principle …”
     “How’s that?”
“They figure it’s old enough that if something hasn’t happened to it yet, it will. But with a little decent maintenance and repair, a space ship’s good for over a hundred years … and a power plant’s good for a lot longer than that because its operating time is only a fraction of that of its ship.” Louis paused for a moment. “Of course, we get a good deal of equipment from wrecked or damaged ships. Got one lad who does nothing but sit up on the roof with a pair of binoculars watching for ships that don’t make the grade …” He let it drop at that because they had reached the boat-tail of the Absyrtis.     Chubb stopped to catch his breath and looked up. In addition to the rust streaking her sides, there was no doubt that this ship was old. The tall, slim, almost regal lines were not those of a modern ship. Modern ships looked efficient; they were. The Absyrtis was merely beautiful, a work of art, the result of a designer with a sense of line and sweep and proportion who had labored over his drawing boards doing work which he must have loved. It was reflected starting from the parabola of revolution of her nose cone down her sleek, unbroken sides to the graceful curve of her boat-tail with its six gaping thrust chambers, and in the swallow-like profile of her drooping wings. It belonged to another day of space flight.
     “Shipped many a ton of lunar ore in this bucket,” Louis said in recollection. “But she was a bitch to handle under thrust. Shake? Man, she’d shake your teeth right out! And the center of pressure would tend to wander forward of the center of gravity if you didn’t watch the mass distribution. Let’s go aboard.” He grabbed a rope ladder hanging down the side of the ship and clambered spryly aloft with an agility which amazed Chubb and LeRoy.
     LeRoy followed and Chubb waited until the other had gained the lock high on the ship before he entrusted his full weight to the ropes. He didn’t look down; if he had, he would have frozen to the ladder with vertigo. He kept his eyes aloft and climbed steadily, hand-foot-hand-foot. He was out of breath when he stepped through the air lock and looked around.
     The tour of the old ship was fascinating. Chubb’s eyes were alight the entire time. It was like a childhood dream come true. It brought up memories entombed by the years and Chubb remembered the toy spaceships which looked like the Absyrtis and the drawings he had hopefully sent to the Space Force at White Sands, crude sketches of a “Sooper Space Combat Rocket”. And there were forgotten memories of a chubby little boy playing spaceman in that pile of boxes in the back yard, dreaming of a space ship the image of which was the Absyrtis.
     Just being in her gave him a feeling of satisfaction he had not experienced for years. Feeling the cold metal of her companionways and smelling the ancient, musty odors of far-off worlds which still lingered in her made him suddenly realize with a pang of sorrow and regret that this could have been his—could have, if he had had a different gene makeup (Chubb's genetic makeup predisposes him to be overweight, not allowed in space crews).
     The Absyrtis was far from a complete space ship. Most of the power plant essentials were missing, the electronics had been stripped, and there were no astrogation instruments. The Absyrtis had seen hand tools, but not a cutting torch.
     “Give her just a few essentials and she’s ready to lift,” Louis remarked, sitting down on an acceleration couch in the barren, echoing control room far forward in the nose. “Many’s the time I’ve sweated it out on this couch, mates. But this old bucket never failed me. A taut, reliable old ship she was. After we converted her to thermo-juice, she saw Mars and Venus and Ganymede. Bailey took her out to Titan once after I got stuck on dirt for keeps. But she knows her way into Dianaport by heart; hardly have to lay a finger on the board for a landing. She just sniffs her way in.”
     “What are you going to do with her, skipper?” Chubb ventured to ask.
     “She’s the last of her kind, mate. The pure-nuclear ships have taken over now. And a new kind of spaceman is flying them. We’re both obsolete, so she stays here with me. Oh, maybe one of these days I’ll get me a red-hot crew together. We may not get high enough to crash, but we’ll still get oft the ground again. The regulation hounds will try to stop us, but to hell with them! It’s a sad thing, mates, when the laws won’t let a man do what he wants or even kill himself as long as he doesn’t hurt anybody else in the process.” The old man’s eyes were on the empty holes in the control panels where instruments, lights, and switches should have been.

---

(ed note: Mr. Louis takes them up on their offer. In exchange for refurbishing the Absyrtis and keeping Louis as captain, he will give them the ship for free)

     Refitting the Absyrtis turned out to be quite a task. The old ship lacked more than was apparent on a cursory inspection. As a result, Chubb closed the doors to his consulting office in order to devote his full energies to the project.
     So he moved in with Luna Louis, sharing the old bachelor’s quarters with him. It was far from being luxurious, but Chubb was having the time of his life. He didn’t really care where he slept or when he ate; he had his hands on a space ship at last.
     Louis turned out to be less senile than any of them expected. He seemed to snap out of his dreamy moods. The transition was strange to behold. Once again, he stood straight and his voice carried the tone of authority and casual competence. His eyes became alert, and his mind sharpened like a rusty knife edge that has been put to the whetstone at long last.
     The youngsters of the SRS were by far the most persistent at the work site. They came in droves on Friday afternoon and stayed on the job until Monday morning when they dragged back across the desert to classes or to their jobs. Many of them came out during the week to perform the many tasks at hand.
     Their first job was a complete and minute inspection of the ship as she stood. No manuals on the Argonaut Class could be found, but Luna Louis turned out to be a man of remarkable memory.
     “Hey, skipper, this valve seat mikes a tenth of a millimeter less than the blade. What gives here?” LeRoy called from the power room on the temporary intercom Bert Eggstrom had rigged.
     Louis answered from the forward radar blister, “Where did it come from?”
     “The feed heater just abaft of the forward tank bay.”
     “That sounds about right, Mister Finch. What’s the condition of the seat and gland packing?”
     “Packing’s shot. But how can this valve seal?”
     “Don’t worry about it. It gets hot in that forward feed heater. Thermal expansion of the seat causes that valve to seal tighter than your old britches. Get the part number off that valve, and we’ll see if maybe I’ve got some packing for it. Pull the whole valve and take it down to the shop.”
     “Right-o, skipper!”
     “Hey, skipper?” Chubb’s voce echoed up the main ship well. “Got a minute?”
     Louis turned to the youngster who was working in the blister with him. “Yank that sweep selsyn, Jimmy. The rotor’s shot. I think maybe one of the units from that old Mark Fourteen radar out in the yard will fit. Don’t bother with those cap screws; knock it loose with a hammer, because you’ll have to drill and tap new holes anyway."
     “How about these waveguide junctions, skipper?”
     “Put the torque wrench to them. They’ll warp back,” the old skipper told him, handing him his tools and crawling out of the little hatch into the main portion of the ship. Wiping the sweat from his neck with a piece of waste, he yelled down the well, “Up here, mate!”
     Chubb came puffing up the ladder from below. “Here’s a survey of the equipment in the boat-tail, skipper.”
     Leafing slowly through the sheaf of papers handed to him, Louis mused, “Not as bad as I expected.”
     “What do you mean, skipper? Half the structural members back there are bent, broken, or missing! Engineering-wise, it’s flimsy as a paper bag!”
     “And just what do you know about space ship structures, Mister Delany?” Louis asked sarcastically. “The tail of this bucket was grossly over-designed. We ripped out those members years ago to make room for the thermo-juice drive.” He handed the papers back to Chubb and told him, “Take them down and give them to that gal who’s doing the consolidation. I’ve got most of these missing parts—or something that will do the job.”
     “Check, skipper. Tank bays and radars are the only lists we need now. Maybe we’d better start thinking about moving the ship out to a launching pad.”
     “Why move her?”
     “Huh?”
     “A fine “engineer you are! What would the costs be? I've got the parts, the shops, and the tools right here.”
     Chubb thought about this. “You mean refit and lift from here?”
     “Is there a better place?”
     “But it’ll wreck your yard when we lift, skipper.”
     “So it will. But once we raise ship, mate, I’ll not be needing this yard any longer.”
     Chubb stared at him for a moment, then quietly went out the hatch and clambered down the hastily-rigged servicing tower. A month ago, he would have paled at the thought of hanging on a slender ladder fifty meters up. He had in fact done so. But it didn’t bother him now, and he was in much better physical shape. It was a matter of pride to him that he had managed to lose five kilos.
     Wandering back through the yard toward the hut they were using for an office, he noticed the change in Luna Louis’ junk yard. Old tools had been ressurected from the heaps, cleaned up, and placed in sheds. Under a ragged tarpoline, three youths were hydrostating valves and pressure vessels; beside them was a jury-rigged flow bench. Farther down the line, he passed a leaning shack in which Bert and several other men were working over old radar gear. A sign over the door proudly announced, “Department of Witchcraft and Sorcery. Slightly Used Pentacles and Klystrons For Sale.”

---

• 

     It took five long months filled with scrounging for old parts, digging around in junk yards all over North America, and draining of funds. Chubb’s savings were long gone. Luna Louis had converted everything he could to cash. Al Olson, being independently wealthy, kept the project on its feet.
     Everybody worked their hearts out. There were long hours. There were the inevitable minor accidents. There were daily crises which threatened to wreck the whole thing. Louis had his hands more that full working with a very green crew. Everybody made mistakes—but nobody made the same one twice. But the day finally arrived when they could start making dry runs of the ship and her equipment.
     The old Absyrtis didn’t look the same at all, Sporting a new coat of brown and yellow paint—a purposely difierent color and marking scheme than that used anywhere else —she was practically a new ship inside and out.
     Chubb stood surveying her in the late afternoon sunlight, taking a break in his schedule for a cigarette. Yes, every one of the hundreds of men and boys who had worked on her could take real pride in her now, he knew. A few more checks, radioactive bricks for her reactor, and propellants were all she needed—plus a trained crew.
     Olson was out pulling the legal strings for the reactor bricks. Chubb had no idea how they were going to be pried loose from the Bureaus of Nuclear Energy, but Al had assured him that there would be no trouble.
     The propellants? Well, Chubb was expecting ten tank cars into El Paso any day. There was no problem there. The “go-juice” for which the Absyrtis had been designed was a commercially-available chemical which would release its energy by thermo-catalytic action. It was cheap, but it was no longer used for space flight.
     The rocket engine is a basically useful device. Rocket engineers found this out many, many years before when they became aware that the military subsidies following the Second World War might not last forever. A rocket can do more than push. It can generate tremendous volumes of gas. It is an essential device for high-speed, high-temperature chemistry. And the jet of hot gases man dig holes. In the open-pit copper and iron mines all over the world, the snarl of rocket engines was a common thing as their exhausts dug holes faster and more economically than the best carbide bits.
     The crew was his only real worry. He knew they were still green as grass, himself included. Space Commander McLaughlin had been right on one point: you don’t learn it all out of the books. Some people had picked up Louis’ training with little effort; others just couldn’t understand the difference between a fitting and a flange or between a selsyn and a klystron, no matter how high their enthusiasm had been.
     “All hands clear the ship!” Louis’ voice came from a portable megaphone from the lock high on the side of the ship. “Stand clear for pressurizing and water-flow checks!”
     Chubb was joined by Bert, who was handling the electronics and had no part in this check of the propulsion system. “Ran the final checks on the radar today, Chubb. That doppler system is all hot to go. Same with the guidance and control.”
     “Good! Did you get the running rabbits off the surveilance screens?”
     “Yeah, found a mis-matched waveguide in the antenna system. How’s Greg doing with the air system?”
     “Had chlorogel all over Deck D the last I saw him,” Chuhb replied. “Sprung a leak in the irradiation chambers.”
     “Tough luck.”
     “He’ll get it fixed. He’s good.” Chubb watched the silent ship for a moment, then asked, “Say, Bert, maybe it’s none of my business, but how come a sharp electronic engineer like you never got into space in the first place?”
     “Oh,” Bert said offhandedly, “eyes for one thing. Plus the fact I’m a lunger.”
     “T-B? You don’t look like it!”
     “Hell, man, I’ve only got one lung—and that’s full of calcification. Why do you think I came to this country? Same reason as Greg: climate.”
     Great space! Chubb thought. What a crew this ship’s got! Greg with arthritis, Bert with one lung, LeRoy with a heart, and the skipper ripe for the grave! And me, twenty kilos overweight!
     “Stand by to pressurize!” came the call from the ship. Through the thick hull of the Absyrtis the two men on the ground heard the slam of valves and the high-pitched, ringing hiss of pressurized gas filling the propellant tanks.
     Nothing ruptured; the tanks held their pressure.
     “What are they doing?” Bert wanted to know.
     “We’ve got a dummy propellant load of water in the tanks,” Chuhb explained, rocking back on his heels with his arms on his hips. “They’ve pressurized to detect leaks and to see if the system will hold pressure. Next they’ll pop the main propellant valves and run the water out through the rocket nozzles to check flow rates and pressure drops.”
     “How can they run the propellant pumps without the reactor to drive them?”
     “They won't need the pumps. LeRoy and the skipper just want flow characteristics. They know what effect the pumps will have and they … Hold it! There they go!”
     It was quite a show. A terrific roar came from the stem of the ship, but no flame lashed out. Instead, the rocket nozzles sprayed solid streams of water which ran off onto the desert sands in a small flood. Thousand of gallons of water spewed out before the flood suddenly ceased with a bang and a hammering sound.
     “Wow! I’ll bet that shut-down opened a dozen joints!” Chubb took off across the desert like a huge ballon being driven before a gale.
     The power room was a mess when he climbed into it. LeRoy and his crew were trying to tighten fittings and stem the gush of water. There was still considerable water remaining in the tanks. Everybody was soaking wet. Chubb grabbed a box wrench, snugged up a leaking fitting, and shouted to LeRoy “Vents open?”
     “Hell, yes! Get that flange tight before we drown!”
     “Open your dump valves and drain those tanks! You’ll never get these fitting tight with ten meters of hydraulic head on them”
     LeRoy leaped for the jetman’s couch and threw switches. “Electrical system’s shorted out by water! Open that hand valve next to you, Chubb!”
     Once the situation was under control, Chubb—looking like a water-loogged whale—sat down on an auxiliary generator and observed. “I thought you guys knew this power room. What a sad show! What would you have done in a real emergency?”

---

(ed note: A torrential thunderstorm undermines the landing pad andthe ship tips. The ship is saved, but...)

     The Absyrtis was canted over at a five-degree angle, and that was that. Chubb and Luna Louis surveyed the situation the next morning and came to the conclusion that any attempt to right the ship might cause her to fall even farther. The only answer was to secure the ship in its present position and proceed. Taking LeRoy’s suggestion, they fastened quick-release clamps on the guys, then promptly safetied them against accidental release.
     The rest of the check-outs on the “Leaning Tower of White Sands”—the name hung on the ship by Greg Shearer —went off more or less as scheduled. They weren’t all successful at first. Bert Eggstrom was the only one who didn’t have more than his share of troubles, but he had them nonetheless. The communication gear worked like a charm, and Bert was very proud the night he logged his first contact with Asgard Space Station as it went over. The computer and the autopilot finally made four consecutively successful dry runs. He had trouble with the radar; instead of tracking the high-flying evening antipodal rocket as intended, it locked onto a flight of ducks migrating south. But it tracked.
     LeRoy kept on finding leaks, sticky valves, broken welds, and loose nuts everywhere. Most of his trouble was with a very green crew. The college students working for him did extremely well, but he had trouble with other kinds of people. Imagine trying to teach a dry-goods salesman how to run a smooth weld.

---

     Greg Shearer was having trouble with the air system, the water recovery system, and the hatches and locks. Being a bachelor like Chubb, he didn’t have the same kind of trouble LeRoy was having, but he had trouble enough nonetheless.
     He had recruited every member of the SRS who would work and who had, like himself, a green thumb and a knowledge of organic and catalytic chemistry. On the first pressure test, gaskets leaked all over the place, but the worst part came when Greg replaced the standard air with the oxy-helium space mix from the air system. It drove everybody choking from the ship. The ship air from the blowers smelled something like a cross between a garbage dump, a stable, and a locker room. In disgust, he and his crew had to replace every bit of chlorogel solution in the system—while wearing respirators.
     In addition, the ship’s water came out a putrid brown for five days while he fiddled with the old and finnicky water recovery system.
     He was still working with it when Luna Louis came around with Chubb for a final inspection on the refitting. Louis inspected the ship with a critical eye, finding things that nobody expected. He suggested here, corrected there, bawled out ninety-percent of the crew for blunders and oversights, but finally pronounced the ship as ready as it ever would be for final checks, provisioning, and space.
     It should have been a day of rejoicing, but for Chubb it was one of anxiety. During the quiet evening hours after supper when everybody sat around listening to Luna Louis spin old space tales of faraway worlds, Chubb could not keep his mind off the subject.
     The final check of the ship would require that the reactor be activated. This meant heavy water (moderator) and thorium, and as far as he was concerned that might take an act of God to get. The Bureau of Nuclear Power didn’t pass that kind of stuff around like tin pennies.

---

     They went in the personnel hatch. The interior of the ship was considerably different than it had been the day they had first walked her decks. New paint glistened on the bulkheads, and the smell of oil and solvents and men was in her again. After going up the main ship well, they emerged into the control room. The new pastahide cushions on the couches shone in the light of the resurrected flouro-units, and the gaping holes in the panels had been filled with instruments, gauges, switches, and winking lights. The computer rack now held a small electronic brain which was capable of flying the ship; Bert had managed to pick it up from Space Force surplus and had rebuilt it. It was capable of reading-in data in any number of ways: from sensing elements in the ship, from ground radio commands, from control panel commands, and from a self-programming keyboard. Its read-out was equally as versatile. Bert regarded it as being several grades smarter than any of the SRS men working on the ship.
     “About time you showed up,” Louis remarked caustically. “Grab a cup of joe and sit down. You might favor me by pouring me another cup while you’re at it. Can’t operate without coffee.” Luna Louis, true to Space Force tradition, had set up three indispensable things immediately on the Absyrtis; in order they were a coffee mess, a loudspeaker system, and a wardroom of division officers who really ran things.

---

     “It has to be that way, Mister Olson,” Louis pointed out. He took a long swig of coffee and went on, “And now we have a slight logistics problem: thorium and heavy water. What do you have to report on that, Mister Olson?”
     “It’s on its way. Be here tomorrow.”
     Chubb sat up and knocked his head against the bottom of the couch above. “Along with the BSC boys who will promptly hang a red tag on the lock?”
     Al Olson smiled knowingly. “Not yet. It seems the UN once passed a Nuclear Energy Act which has been on the books since 2005. It guarantees the delivery of available radioactive substances to non-profit organizations utilizing it for other than commercial purposes. After a little talk with the BNP (Bureau of Nuclear Power) Regional Director in Albuquerque, the way was paved.”
     “What did it cost?” Bert wanted to know.
     “It’s still BNP property under consignment lease to us,” Al replied.

---

     Luna Louis had to supervise the installation of the thorium and heavy water. The current BNP manuals possessed by the two men did not include the procedure for the Argonaut Class, the reactor being a long-obsolete model. This caused Chubb to ask Louis anxiously, “Skipper, are you sure this old reactor has enough soup to lift this ship?”
     “Mate,” Louis said huffily, “if the engineers hadn’t decided to go to the pure nuclear drive, they’d still be using this type of reactor. This old Mark Seven’s a damn-sight more reliable and efiicient per kilogram of mass and has a lower operating count so the ship shielding is lighter. What licked this type of drive years ago was the propellant mass you have to carry … and thermo-juice was more expensive then. The nuclear stuff cost less when they changed over, but this bucket’s flown for twenty years with that fish bowl, and it hasn’t had so much as a pin-hole leak in the heat exchanger. The Baja California power pile can't boast that record, mate!”
     At last, they were ready for the final checks. LeBoy, who had hand-picked his engineering gang, treated the reactor with a great deal of respect now. The power crew started using the particle counters which had been racked at the ready on the power room bulkhead for months. They raised the temperature to a stable plateau capable of running the ship’s generators and of charging the batteries, although ground power was still available to help them out. The other divisions began a gradual phase-over to reactor power but only as an emergency measure.

The landing boat overtook Discovery from below and behind, giving Drake a good look at his ship. The battle cruiser consisted of a torpedo-like central cylinder surrounded by a ring structure. The central cylinder housed the ship’s mass converter, photon drive, and jump engines — the latter needing only an up-to-date jump program to once more hurl the ship into the interstellar spacelanes. In addition, within the cylinder were fuel tanks filled with deuterium and tritium enriched cryogen; the heavy antimatter projectors that were Discovery’s main armament; and the ancillary equipment that provided power to the ship’s outer ring.

The surrounding ring was supported off the cylinder by twelve hollow spokes — six forward and six aft. It contained crew quarters, communications, sensors, secondary weapons pods, cargo spaces, and the hangar bay in which auxiliary craft were housed.

Unlike the interplanetary vessels built during the years of isolation, which all tended to be haphazard collections of geometric shapes, the battle cruiser’s shape was streamlined. Its sleek form was more concerned with the need to keep the jump charge from bleeding off the hull before a foldspace transition than to any requirement for the ship to transit a planetary atmosphere.

Drake listened to the communications between the landing boat and the cruiser all through the approach. As they drew close, he noticed the actinic light of the ship’s attitude jets firing around the periphery of the habitat ring. When in parking orbit, the cruiser was spun about its axis to provide half a standard gravity on the outermost crew deck. The purpose of the attitude jets was to halt the rotation in preparation for taking the landing boat aboard.

Drake was well pleased with what he heard on the intercom during the approach — mostly silence punctuated by a few terse exchanges of information. The complete absence of chatter was evidence of a taut ship and a good crew. He was suffused with a warm feeling of pride as he watched hangar doors (on ship's nose) open directly in front of the hovering boat just as the cruiser’s spin came to a halt.

     “Landing Boat Moliere. You may secure your reaction jets!” came the order from Discovery approach control.
     “Securing now,” the pilot said as he reached down to throw a large, red switch next to his right knee. The message ‘REAC JET SAFE’ flashed on a screen on the control panel.
     “Prepare to be winched aboard.”
     “Hook extended.”

A torpedo-like mechanism exited the open hatch and jetted across the dozen meters of open space to where the landing boat hovered. Attached to the torpedo was a single cable. The torpedo disappeared from view for several seconds, then the approach controller said, “All right, Moliere. Stand by to be reeled in!”

There was a barely perceptible jolt as the cable took up slack, then the landing boat slid smoothly forward. The curved hull of the cruiser and the open maw of the vehicle hatch swelled to fill the windscreen. The boat passed out of Val’s direct rays and into shadow. The dark was short lived, however. As soon as the bow passed into the hangar bay, the windscreen fluoresced with the blue-white glow of a dozen polyarc flood lamps.

There was a harder bumping sensation as the bow contacted the recoil snubber inside the bay. Then the boat was being pulled completely inside by giant manipulators and lifted to its docking area while a steady stream of orders issued from the bulkhead speaker.

“Close outer doors. Stand by to repressurize.”

---

There is a common belief among the uninitiated that a spaceship’s control room is located somewhere near the ship’s bow. In truth, that is almost never the case. Discovery, with its cylinder-and-ring design, was particularly unsuited to such an arrangement. Like most warships, the cruiser’s control room was located in the safest place the designers could find to put it — at the midpoint of the inside curve of the habitat ring.

Actually, Discovery possessed three control rooms, each capable of flying or fighting the ship alone should the need arise. For normal operations, however, there was a traditional division of labor between the three nerve centers. Control Room No. 1 performed the usual functions of a spacecraft’s bridge (flight control, communications, and astrogation); No. 2 was devoted to control of weapons and sensors; and No. 3 was used by the engineering department to monitor the overall health of the ship and its power-and-drive system.

---

An auxiliary screen lit up as a camera mounted on the habitat ring caught the glow that suddenly erupted from the aft end of Discovery’s central spire. Theoretically, the cruiser’s photon drive should have been invisible in the vacuum of space. However, waste plasma from the ship’s mass converters was dumped into the exhaust (gear-shifting the drive into low gear), causing the drive plume to glow with purple-white brilliance as Discovery broke from her parking orbit and headed out into the blackness of deep space.

---

An hour later, the ship was accelerating along a normal departure orbit at one standard gravity while crewmen rushed to convert compartments from the “out is down” orientation of parking orbit, to the “aft is down” of powered boost. The only compartments that did not need conversion were the control rooms (which were gimbaled to automatically keep the deck horizontal) and the larger compartments (hangar bay, engine room), which had been designed to allow access regardless of the direction of “down.”

At the word “zero,” the apparition dramatically changed appearance.  Suddenly, the mirror-sheen (of the anti-radiation protective shield) was gone and a hull of armored steel took its place.  The ship thus revealed was a twin of Discovery.  Its central cylinder jutted from the center of a habitat ring.  Twelve spokes joined the central cylinder to the ring.  A focusing mechanism for the ship’s fusion powered photon engines jutted from the back of the central cylinder, while the business ends of lasers, particle beams, and antimatter projectors jutted from various places on the hull.  The outlines of hatches marked the positions of internal cargo spaces and hangar bays in which auxiliary craft were housed.

The Derringer-class heavy battle cruiser was a design that went back nearly two centuries.  Designed for speed and acceleration, the ring-and-cylinder design was a compromise between a good thrust-to-mass ratio and an adequate low speed spin-gravity capability.  The design was ungainly and fragile looking, but proven in battle.  One advantage the cylinder-and-ring ships had over purely cylindrical designs, if a ship were severely damaged, the habitat ring could be jettisoned whole, or in as many as six separate pieces.

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Ten minutes after departing City of Alexandria, Landing Boat Moliere drew abreast of His Majesty’s Blastship Royal Avenger.  The view through the starboard viewports was awesome.  At the blastship’s stern were the focusing rings and field generators of three large photon engines.  Even quiescent, the engines that drove the flagship gave the impression of unlimited power.  Just in front of the engine exhausts were the radiators and other piping associated with the ship’s four massive fusion generators.  In front of the generators were the blastship’s fuel tanks; heavily armored and insulated to keep the deuterium enriched hydrogen fuel as close to absolute zero as possible.

Drake let his gaze move forward along the blastship’s flank.  The cylindrical hull was pierced in places by large hangar doors through which armed auxiliaries could sortie into battle.  Forward of these were the snouts of a dozen antimatter projectors, Royal Avenger’s primary anti-ship weapons.  The business ends of other weapon systems also jutted from the heavily armored hull.  Interspersed with the weaponry were all manner of sensor gear.

As the landing boat slipped past the blastship’s flanks, they were rewarded with ever changing vistas since Avenger was rotating about its axis at the rate of several revolutions per minute.  So close was landing boat to blastship that it was easy to imagine oneself in a small aircraft flying over an endless plain.  The optical illusion came to an abrupt end when the landing boat passed abeam of the blastship’s prow.

Like most starships, little or no effort had gone into streamlining Avenger.  In fact, the prow was actually slightly concave, and its surface covered with arrays of electronic and electromagnetic sensors.  A hangar door outwardly identical to those that dotted the blastship’s flanks was set flush with the hull at the giant ship’s axis of rotation.

As quickly as the bow portal came into view, Moliere’s pilot fired the attitude control thrusters to halt the landing boat’s forward speed.  Once Moliere had halted in space, he began firing his side thrusters to align the landing boat with the central portal.  A popping noise echoed through the passenger cabin each time the thrusters fired.  When Moliere was lined up with Royal Avenger’s axis portal, the thrusters fired twice more to match the flagship’s rate of rotation.  The hangar door retracted, and Moliere’s pilot nudged his boat toward the lighted opening.  Within seconds, the boat passed into a spacious cavern lighted by million-candlepower polyarc lamps.  There followed a series of bumping and scraping noises, and a gentle tug of deceleration as the landing boat’s forward velocity was halted.  After that, there came a long span of silence interrupted by the sudden sound of air swirling outside the hull.

Moliere had arrived.

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The following memo was sent by the author to NASA administrator Jim Bridenstine and Scott Pace, executive secretary of the National Space Council, on June 30, 2020.

A mission equivalent to Apollo 8—call it “Artemis 8”—could be done, potentially as soon as this year, using Dragon, Falcon Heavy, and Falcon 9.

The basic plan is to launch a crew to low Earth orbit in Dragon using a Falcon 9. Then launch a Falcon Heavy, and rendezvous in LEO with its upper stage, which will still contain plenty of propellant. The Falcon Heavy upper stage is then used to send the Dragon on Trans Lunar Injection (TLI), and potentially Lunar Orbit Capture (LOC) and Trans Earth Injection (TEI) as well.

There are two options for how to do it:

• A. Do mission only using the Dragon and the Falcon Heavy upper stage as flight elements, with the Falcon Heavy upper stage doing all maneuvers, as described above.
• B. Do the mission using the Dragon, the Falcon Heavy upper stage for TLI, and a small propulsion stage (SPS) lifted to orbit by the Falcon Heavy upper stage for LOC and TEI.

Assumptions:

TLI ΔV = 3.1 km/s
LOC and TLI ΔVs = 1 km/s each for capture into Low Lunar Orbit, but less for capture into higher lunar orbits.
Dragon mass = 9.5 metric tons
FH upper stage dry mass = 10 tons
FH upper stage propellant capacity = 109 tons
FH engine specific impulse (Isp) = 348 s = 3.41 km/s exhaust velocity
SPS engine (Isp) = 378 s (LOX/CH₄) = 3.7 km/s exhaust velocity
FH upper stage mass on reaching LEO = 75 tons = 10 ton dry mass + payload, with rest residual propellant. (This number results directly out of SpaceX data that its payload to LEO is 65 tons, and its payload to GTO is 26 tons.)

Option A

Falcon Heavy is launched without payload, resulting in LEO mass of the 10-ton dry stage and 65 tons propellant. After rendezvous and mate with Dragon, the assembled spacecraft has a dry mass of 19.5 tons and 65 tons of propellant. So mass ratio is 84.5/19.5 = 4.33. With the Falcon Heavy exhaust velocity of 3.41 km/s, this translates into a total ΔV capability of 5.0 kilometers per second. After 3.1 km/s used for TLI, this leaves 1.9 km/s for two 0.95 km/s ΔVs for LOC and TEI, enabling capture into a “lowish” lunar orbit and return to Earth.

Option B

The Falcon Heavy is launched with SPS as payload. The SPS includes 7.9 tons of LOX/CH₄ propellant and 1.5 tons of dry mass. Together with Dragon, it has a total mass of 18.9 tons. With a mass ratio of 18.9/11 = 1.717 it has a total ΔV capability of 2 km/s, allowing it to do LOC and TEI going into and coming back from low lunar orbit. The Falcon Heavy upper stage reaches LEO with the 10-ton dry mass Falcon Heavy upper stage, 9.4 tons SPS mass, and 55.6 tons of propellant. After rendezvous and mate with Dragon, the assembled spacecraft will have a total mass of 84.5 tons, with 55.6 tons of that available in the FH upper stage to perform TLI (the remaining maneuvers will be done by the SPS).

The mass ratio of this assembly with respect to the TLI burn is 84.5/28.9 = 2.92. With the Falcon Heavy upper stage exhaust velocity of 3.41 km/s, this means that the Falcon Heavy upper stage will be able to executive a ΔV of 3.65 km/s, or 0.55 km/s more than the 3.1 km/s required. So, there is plenty of margin in this design, and in fact lower-performing propellants such as LOX/RP (348 s Isp) or NTO/MMH (320 s Isp) could be employed in the SPS and the mission would still be feasible as described, with the only penalty being a modest reduction in margin.

Life support and reentry issues

Travel to the Moon and back requires a minimum of six days, and the Dragon should be good for that. However, let’s say we want to add ten extra days to the Dragon’s endurance. A crew member uses one kilogram of oxygen per day. Thus, with a crew of two, ten days would require transporting an extra 20 kilograms of oxygen. If stored in gas cylinders at 3000 psi (as is done in SCUBA tanks), this would require a total volume of 0.075 cubic meters. The Dragon’s internal volume is 9.3 cubic meters, so that less than 1% of the available volume would be required to accommodate such tankage.

Dragon’s thermal protection is designed for reentry from return from Mars. This is a higher thermal protection requirement than return from the Moon.

Other observations

The Artemis program is advancing too slowly. As matters currently stand, it will have no visible accomplishments by the time of the election. Should administrations change, there is an excellent chance it will be cancelled. The Nixon Administration was not sympathetic to NASA’s plans for the human exploration of the Moon and Mars, and in fact cancelled NASA’s post-Apollo Moon base and Mars mission plans. But after Apollo 8, the only actual Moon mission done while LBJ was still president, it became unthinkable to abort the Apollo program short of landing. The best defense that Artemis will have in the event of a change of administrations is real tangible accomplishment: either actually done, or at least clearly imminent. Otherwise, it will be orphaned and likely go the way of Constellation and SEI. This must be prevented.

With Artemis 8, NASA can inspire the nation, restore our space program’s can-do spirit, and astonish the world with what free people can do. We should not miss this chance.

I. Introduction

     THE moons of Mars are an excellent option for human exploration prior to the exploration of Mars. The moons provide a test-bed for many essential technologies that are required for a manned mission to Mars, while removing some of the complex issues that also must be addressed, such as Martian atmospheric entry of very large payloads and the prevention of forward contamination. Further, the moons are a good place to investigate the potential for insitu resource utilization (ISRU), which is an essential element for long-duration missions and possible colonization of Mars. Aside from these advantages, the moons also offer the unique opportunity to study asteroid-like small bodies in the solar system without having to undertake the risk of going into the asteroid belt itself. The study of small bodies will help in answering important questions about the formation of the solar system and the presence of life on other planets. A human mission to these moons will enable the performance of in-situ studies and also the return of samples to Earth, which can be analyzed with all the resources we have at hand without the constraints introduced by deep space operations.

     Due to its larger size and interesting surface morphology, including the presence of numerous craters and at least one large monolith, we believe that exploring Phobos offers the greatest scientific returns for a given cost. Nevertheless, a concurrent study of Deimos’ composition and structure via remote and/or robotic experimentation will provide vital information about the differences between the moons and may shed additional light on the formation of the moons.

     Motivated by these points, the Asaph-1 mission (named for Asaph Hall, the discoverer of the Martian moons in 1877), a manned mission to Phobos, was proposed by this 16-member “Team Voyager” as part of the Caltech Space Challenge held March 25-29, 2013, at the California Institute of Technology, Pasadena, California, USA. The mandate from the senior scientists, engineers, and organizers to the students was to design a manned mission to one of the Martian moons with a launch date no later than January 1, 2041. During the workshop, Team Voyager divided into subsets of student-experts to address such considerations as science objectives, remote-sensing instrumentation, trajectory, propulsion, communications, habitation design, human health, sample return, biologic contamination, and risk. The group arrived at a consensus on key design items by, first, discussing their merits with scientists and engineers from JPL, NASA, Lockheed Martin, and SpaceX; second, voting on them as a group; and third, affixing them to our “wall of truth.” Once a design consideration reached the wall of truth, it became a permanent part of the mission plan. This paper is a summary of the results of our detailed mission plan, including: (1) scientific motivation for the mission, (2) a summary of the mission architecture, (3) first-order details of the mission, such as trajectory design, propulsion systems and habitat design, and (4) a brief discussion of the long term impact of such a mission. Owing to the condensed, intense nature of the workshop some contingencies and peculiarities of the mission, such as abort trajectories, alternative lower-ΔV trajectories, and multiple re-entry scenarios (i.e., aerobraking and aerocapture maneuvers), could not be evaluated.

II. Scientific Motivation for the Mission

     The Asaph-1 mission is motivated by scientific discovery and demonstration of novel technologies, including those needed to support the extended duration of humans in space. Several outstanding physical and biological science questions that may be answered by the mission include:

     (1) What are the compositions, ages, and origins of Phobos and Deimos?

     Phobos is the larger, closer moon with approximate dimensions of 26.8 x 22.4 x 18.4 km. Deimos is the smaller, more distant moon with approximate dimensions of 15 x 12.2 x 10.4 km. To date, only a limited amount of visible imagery and infrared spectroscopic data has been acquired to determine the compositions of either of the moons, which, at least at the surface, consist of phyllosilicates (serpentine and/or kaolinite) with lesser feldspars or feldspathoids. The ages and origins of the moons are unknown. Both moons are very similar in composition to C- and D-type asteroids, which leads to the hypothesis that they are captured asteroids. However, they both have nearly circular and equatorial orbits around Mars, which would necessitate an explanation for the circularization and adjustment of the inclination of their orbits after capture. Additional hypotheses for their origin(s) are: (1) They are remnant debris left over from the Martian accretionary process, (2) They are second generation solar system objects that coalesced in orbit after Mars formed, (3) They are two of many small bodies that were ejected from the Martian surface by collision with a large bolide, (4) They are captured cometary nuclei. Measuring radiometric ages on the moons will help to constrain the formational history of the moons and, by extension, Mars itself.

     (2) Are there any compounds—particularly water, hydrocarbons, or metals—on Phobos or Deimos that could be used for human habitation in space (e.g., to establish a station on one of the moons)?

     Current data suggest that there is no free water (ice) on the surface of the moons. To date, all ‘water’ observed by spectroscopy occurs in hydroxyl groups bound within phyllosilicate minerals. A temperature on the order of ~500°C is required to dehydroxylate phyllosilicates, thereby liberating free water. Such a process may represent an engineering challenge but does not preclude the use of phyllosilicates as a source of water. The estimated densities of Phobos and Deimos are 1.87 and 1.54 g/cm³, respectively. A back-of-the-envelope average of seven common phyllosilicate minerals yields a density of ~2.61 g/cm³. Because the bulk density of the moons is significantly less than the average density of common phyllosilicate minerals, there must be a significant amount of lower density material present within the moons, i.e., various ices or potentially clathrate-like combinations of light hydrocarbons and water. If clathrates were to be found, they could prove useful for human habitation and transportation. The low bulk density of the moons argues against the presence of significant quantities of metals.

     (3) Are there any compounds that may indicate the presence of life?

     As yet, the answer to this question is unknown. Based on the criteria discussed by Clark et al. for small bodies within 2 A.U. of the Sun, it is likely that the Martian moons are sterile. Nevertheless, samples returned from the moons should be carefully shielded from organic contaminants, as these samples may yield important data to help answer this question.

     (4) What are the surface characteristics of the Martian moons, especially with regard to landing a spacecraft there?

     Images captured by MRO suggest that craters on both Phobos and Deimos are partly to completely filled with what appears to be powdery, fine-grained regolith. The craters of Deimos appear to be more filled with powder than those on Phobos. It is critical to know the depth and nature of the powdery regolith in order to make informed decisions about landing a spacecraft on either of the moons.

     (5) What physiological and psychological anomalies can be characterized using scans and samples from our crew during their incursion into deep space?

     Pre-, mid-, and post-mission analyses of crew health indicators will clarify the effects of radiation exposure, extended mission stress, and other, possibly unforeseen, factors on humans.

     (6) What will be the profile of radiation exposure encountered during the mission?

     Radiation data from the Mars Science Laboratory (MSL) cruise phase and the Asaph-1 precursor mission will better define the quantity and intensity of radiation that the crew must endure during the Asaph-1 manned mission to Phobos and, eventually, during the first human mission to the surface of Mars.

III. Mission Architecture

     This section details the mission architecture intended for the Asaph-1 mission, including: the benefits of implementing a precursor mission for such a program, the over-arching mission structure, a general timeline to achieve the scientific and operational goals, and other important engineering considerations, such as technological considerations and strategic knowledge gaps.

A. Phase One: Precursor Mission, Motivation and Benefits

     Just as the Surveyor program evaluated landing sites for the Apollo missions, a robotic precursor mission to Phobos and Deimos will reduce the risks involved in a manned mission by surveying potential landing sites and demonstrating technological feasibility. Phase One of the mission consists of an orbiting, remote-sensing Phobos-Deimos Surveyor (PDS), an impactor-lander Phobos Explorer (PE) and an identical impactor-lander Deimos Explorer (DE). The PDS-PE-DE system (Fig. 1) will launch from Earth in 2026 in a Falcon 9 and will use solar-electric propulsion to spiral out to Mars slowly over the course of two years. Upon reaching Mars in 2028, the PDS system will survey Phobos, its primary objective, and then Deimos and will deploy the PE and DE packages near their respective landing points. Having completed those missions, the PDS will remain in orbit around Mars to act as a communications relay for the Phase Two manned mission.

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     At Mars, the PDS-PE-DE system will enter an areocentric orbit below Phobos with an inclination of 20°. This orbit will cause the PDS-PE-DE system to gradually overtake Phobos, giving surveillance coverage of both the north and south pole regions. Then the surveyor will transition to an orbit above Phobos, which will allow for the mapping of over 80% of the moon’s surface. From this higher vantage point, the PDS will release the PE, which contains an impactor experiment and lander. The impactor package will release four penetrometers to strike widely-spaced sites on each moon (Fig. 2). Using the results from the impactor experiment and the orbiting surveyor, the PE lander will reconnoiter the site most suitable for the landing of the manned mission, with sites ‘A’ and ‘B’ being the priority sites.

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     The PDS system will then enter a higher-altitude Mars orbit, just below Deimos, and will release the DE. Again, this orbit will be slightly inclined from the ecliptic. The PDS will slowly move from below Deimos to trailing it, and then to a higher altitude orbit, thus mapping up to 50% of the moon’s surface. As on Phobos, the DE will release four penetrometers, which will be viewed from this higher altitude. Immediate results from the impacts will determine the landing site for the DE lander. Once the impact experiments have been performed, the PDS will move back down to an areocentric orbit slightly below Phobos, thereby maintaining sufficient communications with both landers. Because both moons are tidally locked to Mars, all of the impactor sites on Deimos, and all but site ‘B’, within Stickney crater on Phobos, have full view of the Martian surface at all times3. Although the explorer packages will necessarily be highly autonomous, this will allow windows for the explorers to communicate information to the orbiting PDS system.

     Although the movements to raise and lower the PDS system do complicate the precursor mission plan, the movement is required in order to survey both moons with the understanding that Phobos is the principal target of interest. Because Phobos is the priority, if the PE were to fail to initialize or if it yielded unsatisfactory results, the DE could be substituted for the faulty PE. If this were to be the case, the secondary raise to Deimos’ orbit would be obviated.

     Both landers will collect scientific data over the course of several years, until their power supplies run out. Meanwhile, the orbiting PDS will make remote sensing observations before, during, and probably after the Phase Two manned mission, and will also act as a key communications relay during Phase Two activities.

B. Phase Two: Primary Mission Overview

     Phase Two, the manned mission, is planned to be an operation with a human crew in which surface operations, including sample collecting, will be conducted on a Martian moon, nominally Phobos, depending on favorable results from the Precursor mission. The crew is anticipated to return to Earth with geological samples and other data collected at the surface. A human crew was chosen to carry out sample collection and operations of this mission, as opposed to a teleoperated robotic system, because human astronauts on the ground are uniquely suited to make rapid decisions about geologic sample collection, and they possess a situational awareness necessary to meet mission goals at Phobos.

     Phase Two is achieved using a sequence of launches from Earth to LEO, where the modules will rendezvous to form the mothership (MS). Once the assembly is complete, the MS will use an impulsive propulsion maneuver to reach the Martian system within six months. At Mars, the MS will enter a parking orbit for approximately one month. During this period, the Space Exploration Vehicle (SEV) will approach the surface of Phobos to perform scientific activities. After returning the crew to the MS, the SEV will return again to the surface of Phobos as a probe to continue autonomous scientific operations over the course of several years. The rest of the MS will depart from Mars using another impulsive propulsion maneuver to return to Earth. A bat chart of the mission (Fig. 3) is provided for easier visualization of the primary mission.

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     The primary mission will utilize the following modules: (1) Propulsion Systems 1 and 2 (PROP1 and PROP2), which contains a nuclear thermal propulsion (NTP) system including liquid hydrogen tanks, (2) SEV, a vehicle that will bring astronauts from the MS to Phobos proximity and back, (3) Deep Space Habitat (DSH), a module that provides additional habitable volume for the crew. (4) Multi-purpose Command Vehicle (MPCV) with Orion Crew Module (CM), a vehicle that serves as the habitable volume shuttle from Earth to the MS, and will be used for the reentry of the crew.

C. Primary Mission Timeline and Considerations

     The primary mission has a nominal duration of 465 days, including a 185-day-outbound transfer, a 30-day stay at Mars and a 250-day-inbound transfer. The crew will leave Earth’s orbit in April, 2033, arrive at Mars during October of the same year, and return back to Earth in July, 2034.

     The determination of the key dates and trajectories for the mission is based on multiple factors. The first trade-off is between undertaking a short-stay (opposition class) mission versus a long-stay (conjunction-class) mission. Considering crew safety issues due to radiation exposure in deep space and taking into account that a longer round-trip duration will lead to a higher probability of contingencies, we prefer the opposition-class mission concept.

     The total ΔV from LEO to Mars, as a function of round-trip time and departure date during the ideal launch window, is plotted in Figure 4A. The investigated departure dates are a result of the time needed to develop the required technologies (leading to a highly optimistic early departure in 2020), with a launch date no later than January 1, 2041, as defined in the mission statement.

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     Concerning radiation exposure, it is most favorable to perform a deep space mission during solar maximum. The first solar maximum within the shown departure dates will peak around 2022 (solar cycle 25); the following solar cycle 26 peaks between 2033 and 2035. Solar cycle 25 is predicted to be one of the weakest in centuries. Additionally, there are only a few possible launch dates in 2022 for an opposition-class mission. For these reasons, April, 2033 is selected for further investigation.

     The total ΔV has been calculated from LEO as a function of round-trip duration (Fig. 4B). It shows that a shorter round-trip duration automatically leads to an increase in the total ΔV required. It should be noted that the smallest ΔV , (i.e., longest round-trip duration) corresponds to the earliest departure date (April 7, 2033). With later departure dates, the round-trip duration decreases while ΔV increases. As a result, April 7, 2033 is determined to be the optimal departure date. This date selection allows for a launch slip of up to 25 days. Choosing this trajectory, there is calculated to be a constant line of sight from the spacecraft to Earth while in transit to and from Mars. Such a line of sight will be highly beneficial for flight control communications and crew safety.

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     Trajectories were calculated using a robust Lambert solver, with ephemerides from JPL. At Mars, a bi-elliptic transfer is chosen to transport the crew safely from the mothership to Phobos. In theory, a Hohmann transfer would be more efficient to do this, where the red diamond marks the used transfer’s position on the graph (Fig. 4C). However, as Mars is only just beginning to capture the spacecraft when starting this transfer, the actual ΔV required to do a Hohmann transfer is a factor of ten larger than the ΔV using the bi-elliptic transfer.

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D. Technological Requirements and Strategic Knowledge Gaps

     It is important to understand the technology required for the accomplishment of the mission. The technologies employed in the mission are currently at various readiness levels. Development time is taken into account in the mission architecture, and some of them will be discussed in detail in later sections of this report. A few of the key technological requirements are as follows: (1) A safe habitat needs to be designed for astronauts to survive for about 500 days in deep space. This includes radiation shielding, smart resource utilization, and comfortable living space for the astronauts. (2) Efficient propulsion systems that provide reasonable thrust at high Isp are required to transport the crew and supplies. (3) Multiple, carefully-timed launches are required to transport all the modules to the Martian system. (4) The capability to abort the mission safely at various stages needs to be assessed.

     In addition, there are certain important strategic knowledge gaps (SKG) that need to be retired before the undertaking of the manned phase of the mission: (1) The surface properties of Phobos and Deimos, such as regolith thickness and strength, are completely unknown and must be characterized before humans can be sent to either moon, (2) Deep space vehicles need to be tested for survival in deep space conditions prior to usage by astronauts, (3) Custom fairings need to be developed in order to accommodate high volume payloads on launch vehicles, (4) Methods for faster turnaround times for launch vehicles need to be developed in order to facilitate more launches in shorter periods of time, which allows for faster assembly of deep space cargo in LEO, (5) On-orbit assembly on a large scale needs to be perfected through research and testing, and (6) Improved thermal protection must be developed to protect spacecraft from the heat generated by reentry velocities in the range of 14-16 km/s.

IV. Details of the Phase Two Primary Mission

     In this section we present pertinent details about specific aspects of the primary mission, including: (1) trajectory, (2) propulsion and vehicle selection, (3) habitation design and considerations for human success in deep space, (4) surface mission operations that will realize the scientific goals of the mission, (5) systems engineering, (6) planetary protection, (7) risk matrices for the mission and program as a whole, and (8) anticipated costs and partnerships.

A. Trajectory

     The proposed trajectory (Fig. 5) is designed for an opposition-class mission with a round-trip duration of 465 days. Neither PROP1 nor PROP2 can be assembled and launched as a whole from Earth. Therefore, the launch campaign for the unmanned modules will start approximately five months prior to crew departure. Both PROP1 and PROP2 will each be brought into LEO through multiple launches over a period of several weeks. The design choice for LEO is further explained in Section IV.B.: Launch Vehicle Selection and Propulsion. After both modules have established a stable orbit of 300 km and are successfully assembled, the DSH will be launched to the same position and docked to the PROP1-PROP2 assembly. Only then, the crew, along with SEV, CM, and Service Module (SM), will be launched on April 7, 2033. The crew will enter LEO to rendezvous with the PROP1-PROP2-DSH assembly. Altogether, these six major components (PROP1-PROP2-DSH-SEV-CM-SM) comprise the MS, which will depart LEO later in April, 2033 for arrival at Mars in October, 2033. The MS will remain there for 30 days before beginning its return to Earth in November, 2033 with a planned Earth arrival in July, 2034. Figure 5A provides an overview of the heliocentric trajectories and the respective dates.

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     Upon successful assembly of the MS, PROP1 and PROP 2 will provide a ΔV of 3.5 km/s in order to achieve a C3 energy of 6.15 km2/s2. This C3 will place the spacecraft on a hyperbolic trajectory for arrival at Mars on October 10, 2033. The Earth escape trajectory will have an outgoing asymptote right ascension of 272°, a declination of -23°, and a velocity azimuth at the periapsis of 90° in the Earth inertial reference frame.

     At Mars, the MS will burn with a ΔV of 2.2 km/s to achieve a Mars Orbit Insertion (MOI) and enter a 250 x 33,813 km parking orbit around Mars (orbital period of 1 sol) with an inclination of 34°. The eccentricity of this orbit (white dashed line in Figs. 5B, C) will aid in the transfer to Phobos’ orbit (dark blue line in Figs. 5B, C) by losing much of the velocity from the approach. What follows is the phasing period, which could require a minimum of twelve hours to a maximum of 14 days. Phasing ends once two criteria are fulfilled: (1) MS and Phobos have a phase difference of 180°, and (2) the first condition is met when the MS is located at the parking orbit apoapsis (Point 2 in Figs. 5B, C).

     As soon as these two criteria are met, the crew will board the SEV and depart for Phobos rendezvous. The desired orbit will be reached through a bi-elliptic Hohmann transfer with apse rotation requiring a ΔV of 0.4 km/s, which will change the SEV orbit inclination to 8° and raise the periapsis to 9377 km (light blue line in Figs. 5B, C). The periapsis will then match the radius of the Phobian orbit. After a 15-hour transfer, the SEV will perform a ΔV of -0.7 km/s to place the crew in a circular Phobos trailing orbit with an inclination of 1° (Point 3 in Figs. 5B, C). The SEV will trail Phobos for a minimal duration of 14 days. This duration can be increased if the initial MS-Phobos orbit phasing requires less than 14 days to complete. The SEV will visit several sites on the Phobian surface, which are described in Section IV. F: Science Mission and Surface Operations.

     Upon completion of all surface operations, the MS will exit the highly eccentric parking orbit and enter the Phobos trailing orbit of the SEV, requiring a total ΔV of 1.1 km/s. Docking of MS and SEV will occur on November 6, 2033. After the crew transfers from the SEV back to the MS, the SEV will return to the Phobian surface. It will use the same anchoring system previously used during EVA activities to attach itself to Phobos. The crew will continue to collect scientific data from Phobos using tele-robotic systems during their return to Earth.

     After two preparatory burns requiring a total ΔV of 0.7 km/s (Points 4 and 5 in Figs. 5B, C), a ΔV burn of 3.7 km/s will send the MS on a hyperbolic return trajectory on November 8, 2033. Arrival at Earth will be on July 16, 2034 with an Earth-relative velocity 16.2 km/s. An additional burn or aerobraking maneuver will reduce reentry velocity to approximately 14 km/s. A summary of the proposed trajectory with ΔV requirements can be found in Table 1.

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Table 1. ΔV summary for MS and SEV mission operations

Description	ΔV (km/s)
Place MS on hyperbolic trajectory	3.5
Mars orbit insertion (MOI)	2.2
SEV burn at apoapsis when Phobos- HEV phase difference is 180° with plane change of 11.6° from ecliptic to 1.1° with respect to Mars’ equatorial plane	0.4
SEV Phobos trailing orbit insertion for astronaut EVA	0.7
MS departure from parking orbit	0.4
Phobos trailing orbit insertion for MS	0.7
Phobos trailing orbit exit when EVA is complete	0.5
Burn at apoapsis to prepare for escape trajectory	0.2
ΔV for Mars sphere of influence escape for return to Earth	3.7
Total ΔV requirement for SEV	1.1
Total ΔV requirement for MS	11.2

B. Launch Vehicle Selection and Propulsion

3. Detailed Design

     The mass of the NTP module is approximated using the same assumptions as the NASA Human Spaceflight Architecture Team. The propulsion system comprises two different modules. The first module consists of the engine and nuclear core as well as some propellant. The second module is a tank carrying the bulk of the liquid hydrogen.

     The first stage consists of two engine cores generating a total thrust of 444 kN, which results in a thrust-to-weight ratio of 0.09. It is favorable to achieve a ratio of 0.1 for an impulsive burn, though in the case of starting from a circular orbit (LEO), it is not as critical as launching from an elliptical orbit. The burn duration is 82 min. The second stage (return trip) generates a thrust of 222 kN, resulting in ratio of 0.12 with a burn duration of 45 min. The elliptical orbit at Mars requires the increased ratio.

     The main propellant for the NTP is liquid hydrogen with a very low density of 70.85 kg/m³. To be able to exploit the full launch mass capacity, modifications to the fairing diameter, as well as length, are required. A simple increase in the diameter has significant implications for launcher performance. In order to increase the payload volume while still meeting the structural and control requirements, a shroud optimized for aerodynamics is proposed (Fig. 6). The optimized configuration allows for a near-doubling of the payload volume while still achieving the same launcher performance.

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     The mass increase of the fairing due to the additional structure is approximated to be 36% of the standard payload fairing design. The standard Atlas-V HLV payload fairing has a mass of 4,400 kg, which results in an increase of 1,600 kg. This increase is subtracted from the launcher performance. Analogously, the Falcon Heavy fairing and performance is adapted. Finally, one has to take into account the additional cost for the development of the new shroud.

C. Habitation Elements

     In developing the habitation elements for the mission, the following general systems architecture guidelines were followed to maximize system and operational reliability and flexibility, and, ultimately, the safety of the crew: (1) Leverage systems that are currently in use or development to minimize development cost and risk, (2) Maximize commonality across all mission elements to increase system robustness, lowering the number of spares required, and decreasing the costs of system development and manufacturing, (3) Maximize multifunctionality and synergies among systems, yielding increased functionality for less mass, (4) Account for crew safety during all mission modes, and (5) Implement lessons learned from past programs. Based on these guidelines, the following architectural choices were made.

1. Deep Space Habitat (DSH)

     ISS-derived habitat structures were chosen as a baseline architecture for the DSH (Fig. 7), with modifications most notably made in the radiation protection to protect the crew for a long duration mission. Using modified ISS modules for the habitat is advantageous as the development work will be minimal, the system reliability has been demonstrated, ISS hardware is already flight-qualified, and ISS infrastructure such as payload racks and MPCV integration can be easily incorporated. The habitable volume is 76.3 m³, which is about 25% greater than the optimal recommended habitable volume for a crew of three for a mission duration of this length, according to the Celentano curve. This habitat will be configured for both on- and off-duty use.

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     The primary Environmental Control and Life Support System (ECLSS) in the DSH is a closed-loop system similar to what is used on the ISS to minimize consumable mass. The secondary ECLSS is a passive system, known as Water Walls, that filters waste products through a series of forward osmosis treatment bags. Including both of these systems in the DSH design provides redundancy and increased radiation protection. The primary ECLSS design was validated for our crew size and mission duration using the software tool Environment for Life-Support Systems Simulation and Analysis developed at the Institute for Space Systems (Institut für Raumfahrtsysteme) at the University of Stuttgart, Germany.

2. Space Exploration Vehicle (SEV)

     The SEV (Fig. 8) is a pressurized “roving vehicle” currently being developed at NASA Johnson Space Center capable of short duration missions. It facilitates flexible exploration by the astronaut in both the intravehicular and extravehicular environments through the use of robotics and spacewalks, respectively. Moreover, the use of suitports in the vehicle enables the rapid transition of crew members between intravehicular and extravehicular activities when required. The SEV has a pressurized volume of 54 m³ and is capable of sustaining a two person crew for a maximum duration of 30 days. Due to the short mission duration for this vehicle, an open-loop ECLSS system architecture has been chosen to ensure high reliability, reduced complexity, and commonality between the vehicle and the Portable Life Support System (PLSS) of the spacesuits.

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3. Extravehicular Mobility Unit (EMU)

     The NASA-ILD Dover Mark III Spacesuit will be used for exploration outside of the SEV. This spacesuit has been baselined by NASA as the next generation spacesuit design, and has been designed to interface with the suitports onboard the SEV. The PLSS, which interfaces with the Mark III suit, will provide life support for the astronauts during extravehicular operations.

4. Orion Multipurpose Crew Vehicle (MPCV)

     The Orion MPCV has been chosen as the baseline Earth reentry vehicle. This vehicle has been under extensive development by Lockheed Martin to support future NASA exploration missions, and has been designed with safety during all mission phases as its primary objective.

5. Spacecraft Atmospheres

     Spacecraft atmospheres were chosen based on those suggested by the NASA Exploration Atmospheres Working Group to ensure atmospheric capability between spacecraft elements while ensuring that pre-breath time for the required EVA frequency is properly accounted for. Table 5 lists the atmospheres selected for each habitation element to be used in the mission. It should be noted that nitrogen was chosen as the diluent gas in each atmospheric composition. The design presented here for the EMU requires no pre-breathe time.

Table 5. Atmospheres selected for each habitation

Habitation Element	Atmospheric Pressure and Composition
DSH	101.3 kPa (14.7 psi), 21% O2 nominally 70.3 kPa (10.2psi) 26.5% O2 during pressurization with the SEV
SEV	70.3 kPa (10.2 psi) 26.5% O2
EMU	57 kPa (8.3 psi) 100% O2 (Mark III suit)
MPCV	101.3 kPa (14.7 psi) 21% O2 nominally 70.3 kPa (10.2 psi) 26.5% O2 during depressurization prior to EVA from the vehicle

D. Human Factors

3. Crew Health Care

     a. Medical care

     Medical equipment and supplies consist of a standard ISS medical kit scaled up from 460 kg to 1000 kg of equipment, including a high-resolution ultrasound imager and expanded surgical supply kit. Medical consumables will also resemble those used in the ISS Health Maintenance System, expanded from 260 kg to 500 kg of pharmaceuticals and other consumable supplies. This provides a total medical supply kit for the mission with a mass of 1500 kg and an approximate volume of 6.5 m3, a size that fits comfortably into the larger mission design.

     b. Psychological considerations

     Long-term spaceflight produces extreme psychological stress, which, if ignored, can result in serious degradation of mental health that puts the mission and crew at risk but, if recognized in advance, can be mitigated. Major sources of psychological stress include isolation, interpersonal conflict, physical deterioration, separation from family, and lack of privacy. To improve the psychological well-being of the astronauts, it is important to provide them with nutritious food, communication with family, entertainment, and exercise throughout the duration of the mission. Typically, astronauts are provided with a variety of dehydrated food for their meals. To supplement their nutritional intake, small plants that serve as a food source may be included in the mission. Psychological benefits may be gained by both maintaining plants and harvesting them to obtain fresh food. When not conducting on-board science experiments, the crew members will be able to spend leisure time much as they would on Earth, reading books, listening to music, and emailing with friends and family.

     c. Countermeasures and mitigation strategies

     As much as possible, deleterious effects of space travel will be minimized through various countermeasures and mitigations strategies (Table 6). Spinning the habitat to create an artificial gravitational force is unreasonable due to the size of the spacecraft. There is a level of risk accepted in astronauts developing long-term adverse side effects due to the microgravity deconditioning. Once the mission is complete, the crew will have access to a full range of medical facilities to regain pre-flight levels of health and fitness.

4. Radiation

     a. Monitoring

     Tissue Equivalent Proportional Counters (TEPCs)--currently in use on the ISS--measure radiation doses for complex radiation fields and should be deployed in several locations in the DSH and SEV to measure radiation levels during transit, exploration, and EVA. Radiation levels throughout the DSH can be actively evaluated using portable TEPCs, allowing the crew to move to the most highly protected region of the vehicle during a solar particle event (SPE). An instrument similar to the Radiation Assessment Detector on MSL (also soon to be deployed on the ISS) will be deployed by the science team on the exterior of the DSH to record charged particle and neutron incidence for scientific use. SPE monitoring will be conducted using the existing network of solar observatories (i.e., SDO, SOHO, GOES) and any future expansion.

     b. Mitigation

     The mission architecture provides for 20 g/cm2 of uniform radiation shielding in the DSH. This degree of shielding is referenced in NASA documentation as the convergent design option for human missions based on an SPE mitigation/ mass trade33. Radiation shields that incorporate low atomic mass materials are capable of suppressing damaging secondary radiation in the form of neutrons that are ejected during particle transit through the aluminum hull of a module.

     c. Exposure estimates

     NASA has calculated the safe number of days that a person can travel in space when their vehicle is designed as mentioned above. These values are based on the need to prevent astronauts from exceeding an increased risk of 3% for REID (at the 95% confidence level). Failure to mitigate the effects of GCR and SPEs could lead to acute health effects including radiation sickness leading to incapacitation or death. Long-term risks include carcinogenesis, neural tissue damage, stem cell disturbances, and cataracts.

E. Science Mission and Surface Operations

1. Precursor Operations

     The goals of the precursor mission, in order of importance, are as follows: (1) to determine if humans can safely land on Phobos during the primary mission, or on Deimos in the event that Phobos is not feasible, (2) to establish a communications relay system that will facilitate the primary mission, (3) to gain important information regarding the nature and composition of the primary landing site to plan for a landing of the primary mission, and (4) to acquire remote sensing data on both of the moons to be used to understand their composition.

     In order to carry out the primary mission of landing humans on one of the Martian moons, we must characterize the structure and surface properties of Phobos and Deimos. This will be achieved on both moons using four impactor experiments at preselected sites, in-situ sampling and analysis conducted remotely using an immobile lander with an extendable arm, and a combination of remote observations from the PDS. In-situ sampling sites will be determined based on the findings from initial remote sensing surveys conducted by the PDS and from the impactor experiments.

     Impactor sites were selected in order to target sites of geologic interest, sites where future missions might land, and other widely-spaced sites to learn more about the distribution of the surface characteristics. The surface characteristics revealed by the four impactor tests will be a strong driver in determining how and where the lander is deployed and how and where the manned mission will dock and operate.

     To reduce complexity, DE and PE will be identical lander and impactor packages. The impactor package will be modeled after the one planned for the Japanese Lunar-A mission, but with four penetrometers instead of two. The Deimos and Phobos landers could be modeled after the Philae lander used in the Rosetta mission.

2. Science Instrumentation

     The primary instrument objective is to assess the surface environment to optimize human interactions with the surface environment of Phobos. In order to do this it is important to execute a comprehensive study of the planetary bodies to ensure the safety of the astronauts and the completion of mission objectives. The instrument suites have been designed to investigate the nature of the surface and subsurface of the Martian moons. This is a useful investigation for several reasons: (1) Determination of the nature of the regolith (uppermost, loose ‘soil’) allows assessment of the mechanical and chemical properties of the surface, (2) Identifying the strength and porosity of the surface provides critical information to help plan docking and anchoring maneuvers during the manned component of the mission, and (3) Studies of the flux of interstellar material and radiation levels will help to develop shielding techniques.

     Three unique science instrument suites (Surveyor, Explorer, and Expedition; Table 7) have been designed to achieve the aforementioned science objectives during the mission.

     The Surveyor suite is comprised of a number of heritage spectrometers and cameras, configured to investigate regolith properties remotely from orbit. Instruments in the Surveyor suite will provide valuable data on the topography of Phobos and Deimos, the flux of interplanetary material crossing the orbital plane of Phobos and Deimos, surface mineral composition, volatile abundance (such as water and CO2), and the strength of the magnetic fields on the moons.

     The Explorer suite is modeled after instruments from past NASA and JAXA missions35-42. The penetrometer device contained within the impactor package is modeled after the piezoelectric sensing element used in the Huygens probe. It was uniquely calibrated to withstand cryogenic temperatures, and future development will allow impact velocities of 300 m/s. The voltammetry, spectroscopy, and x-ray diffraction/fluorescence instruments (Wet Chemistry Lab, LIBS, and CheMin, respectively) do not require modification and are replicas of the original instruments. The Phobos and Deimos landers will employ robotic arms built on 360° swivels to deliver multiple regolith samples to the experiment chamber. Lastly, an additional micrometeroid detector (modified for a lander spacecraft) will be deployed in the Explorer suite to assess impact rates and material deposition. This instrument will provide details about the nature of the landing environment in which astronauts will execute future EVAs. Once positioned on the surface of Phobos or Deimos, micrometeoroid detector panels will deploy along the sides of the lander.

     Astronauts will manually deploy the Expedition suite of science instruments during EVA sorties. Seismic and radiation studies will be undertaken using heritage instruments. The PRSC (Planetary Retrieval of Subsurface Cores) will be based on core drilling that was done on the moon during the Apollo 15-17 missions but will have a somewhat larger core diameter for increased sample return. The ChipSat instruments will be developed as a public outreach effort to achieve the aims of independent science groups from around the world. Together, the employment of these instruments represents an innovative approach to meet a principal science objective of both on-the-ground data collection and sample return; they also promote the use of scientific equipment that is smaller in scale and lighter in weight.

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3. Manned Phobos Operations

     Although one could argue that many of the mission’s scientific goals could be achieved through robotic means, there is a decided advantage to having humans “on the ground” to collect samples and to deploy instruments. Humans are versatile in that they can evaluate samples for quality and quantity in real time and can troubleshoot instruments on the fly. Up to this point in time, no robotic mission has returned extraterrestrial samples to Earth, and those samples that have been returned via manned EVAs have reaped great rewards for the scientific community.

     With these points in mind, the primary mission is designed to have two human crew members collecting samples directly on Phobos’ surface. The largest challenge to realizing this task is the near-zero gravity of Phobos. To operate on the surface, the crewed SEV will perform a rendezvous and docking procedure with the moon at each of the two pre-selected landing sites, where the vehicle will be anchored to the surface. Whether a conventional harpoon or drilltype anchor will be used, as opposed to an unconventional method such as microspines or netting47,48, will depend on site surface material characteristics (grain size, depth, density, cohesion). This composition information will be provided by data collected during the precursor mission.

     Once on the surface, the astronauts will have two modes available for EVA operations, depending on surface conditions. The first mode consists of one astronaut collecting samples and placing instruments with their feet fixed to the end of a robotic arm that extends from the SEV. In this configuration, one crew member must remain inside the vehicle in order to operate the robotic arm. This type of EVA has been shown to provide the most mobility of the methods investigated during the NEEMO under-water simulation program for manipulation of equipment in a microgravity environment. The robotic arm configuration would be especially advantageous if the surface regolith proves to be so thick and fine-grained that conventional maneuvering is unfeasible. The second mode, appropriate for sand- to boulder-sized regolith, anchors the astronauts to the Phobian surface using a tether and a scaled-down version of the regolith anchor used by the SEV. A secondary safety tether is connected to the SEV. For safety purposes, this second mode nominally involves only one crew member on EVA at a time, while the other performs monitoring and non-EVA activities inside the SEV. For both modes, use of an MMU-type device may aid astronaut maneuvers on the surface.

     Surface activities include collecting geologic samples and placing seismometers and retro-reflectors, as well as other experiments, such as ChipSat deployment. A full schedule of surface operations for the two SEV crew members over the two-week mobilization on Phobos is shown in Table 8. The Phobian surface exploration segment of the mission is designed for a nominal length of 14 days, as constrained by the planned mission trajectory. Using state-ofthe- art portable life support technology and relevant suit design, the safe duration for a single EVA has been estimated to be approximately four hours. Considering both rest periods and the constraints of the PLSS, the four-hour-EVA duration will allow for a maximum total of ten EVAs. Including contingency PLSS operational supply and potential for unanticipated required surface activity, a target number of eight EVAs has been planned, with four EVAs at each of the two predetermined landing sites.

     Surface samples will include rock and regolith scoop samples, as well as drilled core samples. Drill cores are planned to be 40-50 mm diameter x 3 m in length. The drill will be an electrically powered percussive hammer system, with a similar foot treadle contingency design for core removal as used on the Apollo 15-17 missions. Core samples will remain in their sleeves for direct placement into storage on the SEV. Thin samples of top-layer, fine-grained regolith will also be collected using adhesive pads. This will allow specific study of the regolith immediately exposed to the space environment. Loose geologic samples in collection bags and core samples will be stored in an exterior containment unit that will be placed in the SEV airlock using the robotic arm. The samples will be stored at appropriate cryogenic temperatures once on the SEV. Upon returning to the DSH, drill core will be stored in the modified MELFI freezer along with biologic samples to bring back to Earth.

     According to the surface operations schedule, on days three and ten passive seismic arrays will be placed on the Phobian surface to record seismic waves generated by internal strain in the moon. At each of the two landing sites, the seismometers must be placed with a spacing of 10s to 100s of meters apart and the exact location of each instrument recorded. EVA mode two would be preferable for this experiment, as it allows astronauts greater reach, and seismometers may be placed farther apart, which in turn, allows for deeper imaging into the crust of the moon. Inclusion of an active-source seismic array remains under consideration.

     On day two, one or more retro-reflector(s) will be placed on the Phobian surface. Retro-reflectors are mirrors that are used to reflect an electromagnetic signal back to its source. This instrument, once placed on Phobos, will have future application when a signal can be directed to the moon from rovers or stations on the Martian surface in order to determine the orbital distance of Phobos. The reflector measurements are regularly made over a long period of time (i.e., decades) to determine deviations in orbit. This method has yielded excellent results using our own moon, and we anticipate that it will answer such scientific questions as the rate at which Phobos is encroaching on Mars.

     After the full two week period on the surface, the SEV crew will return to the DSH and send the SEV (remotely) on a return path to Phobos, where it will re-anchor to the surface to prevent risk of drift-off and to comply with the requirements of planetary protection. The crew will be able to operate the SEV robotic arm remotely from the habitat, in order to continue to perform surface experiments after completion of the main mission and to demonstrate feasibility of performing telerobotic operations from orbit.

Many readers may find the plots of some SF novels deeply implausible. “Who,” they ask, “would send astronauts off on an interstellar mission before verifying the Go Very Fast Now drive was faster than light and not merely as fast as light? Who would be silly enough to send colonists on a one-way mission to distant worlds on the basis of very limited data gathered by poorly programmed robots? Who would think threatening an alien race about whom little is known, save that they’ve been around for a million years, is a good idea?”

Some real people have bad ideas; we’re lucky that comparatively few of them become reality. Take, for example, a proposal to send humans to Venus. Not to land, but as a flyby.

After the Apollo program had landed humans on the Moon, the obvious question was, “What next?” Some proposals were carried out: Skylab space station¹; U.S.-Soviet cooperation in orbit. Other proposals were binned because there was no money for such things or because they were obviously stupid.

The Manned Venus Flyby would have been both expensive and stupid.

The mission would have re-purposed Apollo-era equipment for a far more ambitious journey. Rather than a week or so in space, the astronauts would have spent more than a year on a slow cruise past Venus. Rather than expect the astronauts to spend this time in the cramped conditions of a Command Module and LEM, the Manned Venus mission would have converted a hydrogen tank into living quarters once it had served its original purpose and was no longer filled with liquid hydrogen. The interplanetary vehicle that resulted would have been quite impressive even by modern standards, let alone those of the Apollo era.

Of course, the mission was not intended to land on Venus. If you could get down to the surface (or what passes for a surface on Venus) you couldn’t get back up to the spacecraft. Venus is nearly as massive as Earth and its escape velocity is not much lower. Without in-situ resource utilization, the fuel demands for an Earth > Venus’ surface, Venus > Earth mission would have been intractable.

Not to mention the fact that Venus is a hell planet. The lower reaches of its dense poisonous atmosphere are hot enough to melt lead. Sending astronauts down to the surface would merely have tested how close to the surface they could get before the ambient conditions killed them.

Happily, that was not what was proposed.

Instead, the astronauts would have been sent on a flyby that would last from late October of 1973 to early December of 1974. The encounter with Venus would have occurred in early March 1974. While close to Venus, the astronauts would collect a wide variety of data about that world and its interplanetary neighborhood (which includes Mercury). They would also give the U.S. a reason to wave the flag and boast of achieving the first interplanetary manned mission. USA! USA!

If I sound unappreciative of this bold plan, you are right. I think it’s cockamamie. Because:

The mission does not do anything robotic missions could not do more cheaply. While humans are a lot more flexible than machines, they’re difficult and expensive to feed and protect. Not only do you need to pay for the fuel to toss humans across space, you need to pay for everything needed to keep them alive as well. Note that what we have actually done is send robots to explore Venus and Mars, as well as other worlds.

(But, you say, we would learn so much about how to feed and protect crew, which we cannot do without crewed missions. Hey, we’re still working on keeping humans alive on space stations safely below the Van Allen belt. That’s enough for now.)

An even more important reason why the Manned Venus Flyby would have been a bad idea (even if Congress had been inclined to fund it—which it was not) is that the interplanetary environment was more challenging than folks in the ‘70s understood. The Apollo-moon-mission-era solution to spacecraft radiation shielding was to hope very, very hard that no major solar storm would occur on the way to and from the Moon. As it turned out, this worked—which is good because a major storm would have definitely killed the Apollo astronauts. Hoping for good space weather would have been a no-go for a four-hundred- day mission, so a Manned Venus Flyby would have required a radiation shelter, yay. What the proposers could not have known, however, is that their mission would have run into a coronal mass ejection in July 1974, one major enough to overwhelm any currently implementable shelter². This would have been fatal for the astronauts.

While this would at least have provided a distraction from Watergate, President Nixon probably wouldn’t have found it pleasant to explain to the press just how the U.S. lost a crew in deep space.

So the next time you set down a science fiction novel and think “nobody would be dumb enough to send people off on an obvious one-way trip to certain death”³, just remember that at one point in recent history, sending a collection of astronauts off to be crisped like KFC chicken seemed like a reasonable idea.

Footnotes

     1: As evidenced by the graphic linked above, Skylab’s launch marked the beginning of a multi-decade period in which there was always at least one space station (usually Russian) in low Earth orbit, in a chain that runs Skylab, Salyut 3 through 7, Mir, the ISS, Genesis 1 and 2, and Tiangong 1 and 2. Not all of these were actually crewed but still, for the lives of most people now living on Earth, there’s always been a space station in orbit.

     2: The initial proposal predated the OSO 7 spacecraft’s confirmation of CMEs (coronal mass ejections) in the early 1970s, so it’s not surprising the original vision didn’t have an effective contingency plan.

     3: A surprising amount of Canadian history was shaped by the British decision to appoint John Franklin, a man whose previous exploits included nearly drowning in a river, and losing eleven of twenty men in his Coppermine expedition, as leader of an expedition to search for the Northwest Passage. Poor planning and Victorian-era canning technology afflicted his mission with scurvy, TB, hypothermia, starvation, lead poisoning, and what gamers call “a total party kill.” Franklin’s final expedition didn’t directly provide any information to the Empire, what with the whole being-too-dead-to-report-their-findings thing. Silver lining: the people who tried to track the vanished expedition did provide useful info. Oh, and we learned that you should not put John Franklin in charge of arctic expeditions.

What it was: A proposed post-Moon landing manned mission using Apollo hardware. It would have launched during a good alignment of Earth and Venus in November 1973 and taken three astronauts on a flyby of the planet Venus, returning to the Earth 13 months after launch.

A later variation of the mission ambitiously suggested using a better conjunction in 1977 to visit Venus and Mars on an outbound leg and Venus again on the Earth-return leg, however most of the work done considered the shorter Venus flyby.

Details: By the mid-1960s NASA was well aware that if they successfully completed the Apollo moon landings they would probably face a severe decline in budget for the manned space program. In the hopes of proving their ongoing worth they developed a few different post-Apollo proposals using evolutionary versions of the Apollo hardware, including plans for a manned lunar base, space stations, and planetary exploration. The latter two of these goals were at first grouped under the name Apollo X, and then became the Apollo Applications Program (AAP).

By far the most ambitious of the AAP missions was a manned flyby of the planet Venus. After two preliminary missions in Earth orbit to test the technology, a Saturn V launch would lift an Apollo Command Module into orbit. As in a typical mission, the first two stages of the rocket would be jettisoned. However the uppermost stage, the Saturn IVB, would be kept and drained of any remaining propellant. Using gear stored where the Lunar Landing Module would have been placed in a Moon mission, the astronauts would then rig it as a habitation module.

The resulting 33-meter-long spacecraft would leave Earth orbit on October 31, 1973 and travel towards Venus for 123 days. There would be a flyby on March 3, 1974. The craft would have been aimed to pass Venus as close as 6200 kilometers above the surface (one planet radius) very quickly—orbital mechanics would have it moving relative to Venus at a clip of 16,500 kilometers per hour—crossing the lit side of the planet. A sidescan radar would map the portion of the planet they could see as they flew by, and the astronauts would perform spectroscopic and photographic studies.

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After that burst of activity the MVF craft would then return home, taking 273 days more to loop out to 1.24 AU from the Sun on a hyperbolic trajectory and eventually swing back to Earth. The astronauts’ landing on Earth would happen on December 1, 1974—total mission time would be 396 days. The Triple Flyby variant would have taken more than 800 days starting in 1977.

When not at Venus, the MVF astronauts would have studied the Sun and solar wind as well as making observations of Mercury, which would be only 0.3 AU away two weeks after the Venus flyby. To keep them occupied otherwise their habitation capsule would have been outfitted with a small movie screen (to show 2 kilograms of movies allowed), and a “viscous damper exercycle/g-conditioner”. The crew would also be allowed 1.5 kilograms of recorded music, 1 kilogram of games, and 9 kilograms of reading material. Hopefully they would choose wisely.

What happened to make it fail: The MVF was part of the Apollo Applications Program, and the AAP was killed dead on August 16, 1968 when the House of Representatives voted to cut its funding from US$455 million to US$122 million. President Johnson accepted this as part of a larger budget deal that kept NASA’s near-term goals safe, though even at that the agency’s entire budget dropped by 18% between 1968 and 1969. The only AAP mission to survive was Skylab.

What was necessary for it to succeed: It’s tough to get this one to work as it’s difficult to see any advantage to sending people on this mission. Mariner 5 had already flown by Venus in 1967 and NASA was able to send a robotic orbiter as part of the Pioneer 12 mission in 1978, just a few years after MVF would have flown.

Even the many probes that the MVF would leave behind at Venus had no obvious connection to the manned part of the mission; it would have been easier to send an unmanned bus of similar size and drop the probes that way. There would be no need then for heavy food, water, or air, or the space for people to move around. And unlike the manned mission there would be no need to bring the bus back, greatly reducing the mission’s difficulty. About all the manned mission had going for it was an opportunity to see what kind of effect a year in microgravity would have on humans, and that could just as easily be determined using a space station in low Earth orbit.

On that basis we also need to be aware that Congress asked hard questions about the purpose of NASA’s manned Mars mission plans in the late 1960s and were hostile to all of them. If Mars wasn’t going to get any money, it’s hard to see what could influence them to fund a mission to Venus.

Finally it needs to be pointed out that no matter even if the MVF launched, nature itself probably had this mission’s number. We didn’t have a very good understanding of the Sun at that time, having only observed one solar cycle from above the atmosphere when the flyby was proposed in 1967. While the launch window was deliberately chosen to be near a solar minimum, and the flyby craft was to have a radiation lifeboat in the equipment module, the mission would have run into an unforeseen natural event on the way back to Earth.

On July 5-6, 1974 the Earth was hit by a big coronal mass ejection (CME), a storm of electrons and protons thrown off of the Sun. People down on Earth were protected by the planet’s magnetic field, as usual, but the astronauts coming back from Venus wouldn’t have been so lucky. Their line to the Sun was several degrees off from the Earth’s (at the time they would have actually looped out past Earth as their trajectory slowly took them back home), but CMEs can cover quite a bit of space. Had the mission actually flown, the astronauts on-board may well have died of radiation sickness after being hit with more (and more energetic) solar protons than their spacecraft was built to handle.

The saving grace here is that coronal mass ejections were discovered in 1971, so the initial plan probably would have been called off rather than risk casualties, or at least be reconfigured to give the astronauts the protection the 1967 plan failed to give them.

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“Manned Venus Flyby” was a 1967–1968 NASA proposal to send three astronauts on a flyby mission to Venus in an Apollo-derived spacecraft in 1973–1974, using a gravity assist to shorten the return journey to Earth.

Apollo Applications Program

NASA considered a manned flyby of Venus in the mid-1960s as part of the Apollo Applications Program, using hardware derived from the Apollo program. Launch would have taken place on October 31, 1973, with a Venus flyby on March 3, 1974 and return to Earth on December 1, 1974.

Background

The proposed mission would use a Saturn V to send three astronauts to fly past Venus in a flight which would last approximately one year. The S-IVB stage would be a 'wet workshop' similar to the original design of Skylab. In this concept, the interior of the fuel tank would be filled with living quarters and various equipment that did not take up a significant amount of volume. The S-IVB would then be filled with propellants as normal and used to accelerate the craft on its way to Venus. Once the burn was complete, any remaining propellant was vented to space, and then the larger fuel tank could be used as living space, while the smaller oxygen tank would be used for waste storage.

Only so much equipment could be carried in the hydrogen tank without taking up too much room, while other pieces could not be immersed in liquid hydrogen and survive. These sorts of systems would instead be placed in the interstage area between the S-IVB and the Apollo Command/Service Module (CSM), known as the Spacecraft-LM Adapter (SLA), which normally held the Apollo Lunar Module on lunar missions. To maximize the amount of space available in this area, the Service Propulsion System engine of the CSM would be replaced by two LM Descent Propulsion System engines. These had much smaller engine bells, and would lie within the Service Module instead of extending out the end into the SLA area. This also provided redundancy in the case of a single-engine failure. These engines were responsible for both course correction during the flight as well as the braking burn for Earth re-entry.

Unlike the Apollo lunar missions, the CSM would perform its transposition and docking maneuver with the S-IVB stage before the burn to leave Earth orbit rather than after. This meant the astronauts would fly 'eyeballs-out', the thrust of the engine pushing them out of their seats rather than into them. This was required because there was only a short window for an abort burn by the CSM to return to Earth after a failure in the S-IVB, so all spacecraft systems needed to be operational and checked out before leaving the parking orbit around Earth to fly to Venus.

Precursors to the Venus flyby would include an initial orbital test flight with an S-IVB 'wet workshop' and basic docking adapter, and a year-long test flight taking the S-IVB to a near-geostationary orbit around the Earth.

Scientific objectives

The mission would measure:

• Atmospheric density, temperature and pressure as functions of altitude, latitude and time.
• Definition of the planetary surface and its properties.
• Chemical composition of the low atmosphere and the planetary surface.
• Ionospheric data such as radio reflectivity and electron density and properties of cloud layers.
• Optical astronomy - UV and IR measurements above the Earth's atmosphere to aid in the determination of the spatial distribution of hydrogen.
• Solar astronomy - UV, X-ray and possible infrared measurements of the solar spectrum and space monitoring of solar events.
• Radio and radar astronomy - radio observations to map the brightness of the radio sky and to investigate solar, stellar and planetary radio emissions; radar measurements of the surface of Venus and Mercury
• X-ray astronomy - measurements to identify new X-ray sources in the galactic system and to obtain additional information on sources previously identified.
• Data on the Earth-Venus interplanetary environment, including particulate radiation, magnetic fields and meteoroids.
• Data on the planet Mercury, which will be in mutual planetary alignment with Venus approximately two weeks after the Venus flyby

Now this is audacious. Boeing sure thought big back in 1968.

Yes, there were quite a few proposed Mars missions back then. Many of them used multi-staging, discarding tanks and engines to increase the mass-ratio.

But none of them had stages with Freaking NERVA atomic engines, tossing five nuclear reactors glowing with radioactive death into eccentric solar orbits. They'll stop emitting dangerous radiation in only a few thousand years.

On the plus side the relatively huge specific impulse of the NERVAs means this monster spacecraft can boost more than one hundred metric tons of payload to Mars; including a huge habitat module, one of those workhorse North American Rockwell Mars landers, a pallet of scientific experiments, and re-entry vehicle to return the crew to Terra.

The crew compartment provides a pressurized shirt- sleeve environment for the crew and storage for equipment which needs a thermal or pressure environment or is expected to require maintenance. Atmosphere within the crew compartment is nominally 7 psia (48kPa) O₂/N₂, 70°F and 50% relative humidity. The crew compartment consists of a 17.8-foot (5.4m) cylinder, 22 feet (6.7m) in diameter (decks 2 &3), joined at both ends by hemispherical bulkheads (decks 1 & 4). A meteoroid bumper surrounds the cylindrical section of the crew compartment (decks 2 &3). Overall length of the crew compartment is 39.8 feet (12.1m) which provides a total volume of approximately 12,250 cubic feet (347m³). Total pressurized volume within the crew compartment is estimated to be 10,000 cubic feet (283m³) for 500-day class missions with the free volume (major areas unoccupied by equipment) 5400 cubic feet (153m³) or 900 cubic feet (25.5m³) per man (which is ample). A surface area of approximately 1200 square feet (112m²) is provided by the cylindrical portion of the crew compartment.

The internal arrangement of the crew compartment results from having to contain within the selected 22-foot (6.7m) diameter pressure compartment a floor area requirement of approximately 1400 square feet (130m²) and ceiling height of 7 feet (2.1m) in order to provide sufficient volume for equipment and men. As a result, the crew compartment consists of four separate levels of activity. Each level is designed to include those crew operations or equipment operations of a similar nature. The levels have also been located to minimize the interface or distance between levels of similar activities. An example is the above/below arrangement of the two levels which include all areas and equipment associated with spacecraft operations and crew living quarters. Equipment and cabinets within the crew compartment and located near the walls are attached in place and do not have provisions for removing or hinging the entire cabinet to expose walls for puncture repair caused by meteoroids. Previous inhouse studies such as Manned Orbital Laboratory have indicated a greater reliability benefit can be achieved by using a weight equal to the hinging mechanisms in the meteoroid shield itself.

Activities of a relatively quiet nature are located on Deck l. In general, this deck includes the sleeping quarters, dispensary, and personal care facilities. Each crewman is provided with a separate room to be used for sleeping and stowage of personal hygiene supplies such as clothes, cleaning pads, and personal care items. Cabinet space is also available for other equipment associated with the mission module. The rooms also provide solitude for crewmen if desired, and allow a crewman to be isolated should the need exist. Approximately 110 cubic feet (3.1m³) of free volume is provided per room. Included within the dispensary is the necessary equipment for crew psychological/physiological monitoring, medical/dental equipment and supplies, and physical conditioning equipment for the cardiovascular system and musculoskeletal system of the body. Personal care facilities include a zero-g shower and waste management system (toilet). Adjacent to the waste management system is the urine water recovery unit. After processing, this water is transferred to holding tanks on Deck 2. Located in the upper portion of Deck l is a pressure hatch leading to the EEM (Earth Entry Module, reentry vehicle) transfer tunnel. A centrally located, 36 inch (0.91m) diameter hatch leads to Deck 2.

Activities of a relative high intensity are located on Deck 2. In general, the activities include the command/control center, combination food storage/preparation area, and recreation area. The command/control center includes the necessary displays and controls to monitor and control all subsystem operation, environment parameters, and vehicle operations such as attitude changes, rendezvous, and dockings. The control center is occupied at all times. The food storage/preparation area includes freezer, hot water provisions, and food storage cabinets for missions greater than 500 days. Dining facilities are also included in the area. Another section of this area contains the remainder of the water management system consisting of the wash water/condensate water recovery unit and a 2-day water supply. Water for crew consumption comes to this supply from the makeup water supply located on the third deck. Storage for wash pads occupy the final bay in this area. The remainder of Deck 2 is used for recreation, conference room, and storage for spares (redundancy). Dividing the recreation area and food storage/preparation area is a bay for electronic equipment with the most significant being the control moment gyros (CMG) of the attitude control subsystem. Located in the center of the floor of this level is the pressure hatch leading to the radiation shelter on Deck 3. Also located in the floor are nonpressure hatches which allow access to the equipment bays of Deck 3.

The major features of the third deck are the combination radiation shelter/emergency pressure compartment and equipment bay. Height of this deck is approximately 10 feet (3.1m) rather than 7 feet (2.1m) as for the other decks due to the design feature of the radiation shelter. The radiation shelter consists of an inner compartment 10 feet (3.1m) in diameter and 7 feet (2.1m) high which also serves as the emergency pressure compartment should the remainder of the crew compartment become uninhabitable for short periods of time. A total volume of 600 cubic feet (17.0m³) is provided by the radiation shelter with approximately 60 cubic feet (1.7m³) of free volume available per crewman. The shelter also provides quarters for the crew during periods of high radiation. These periods include passing through the Van Allen belt anomaly while in Earth orbit; during the firing of each nuclear propulsion module, particularly during departure from Earth as the space vehicle may pass through the heart of the Van Allen belt, and the firing of PM-3 (the nuclear engine module directly adjacent to the crew quarters) when a minimum of hydrogen is between the crew and Nerva engine; and during major solar flares which may last up to 4 days. Because the shelter may be occupied for extended periods of time and during nuclear propulsion firings, it is necessarily provided with sufficient displays and controls to enable the crew to continue space vehicle operations. A 4-day emergency food, water, and personal hygiene supply is provided within the shelter as well as separate atmosphere supply and atmosphere control loops. Each crewman is provided with a storage compartment, which contains his pressure and emergency provisions. Should the crew compartment become uninhabitable, all crewmen transfer to the shelter and don pressure suits. A repair team can then be sent out to correct the malfunction. The final item housed in the shelter is the photographic film used in the experiment program. This location has been selected as it provides the maximum amount of radiation shielding at no additional weight penalty.

The bulk of the radiation protection for the shelter is provided by a 20 inch (0.5m) thick combination food/waste storage compartment. This storage compartment contains the initial 500-day supply of food and surrounds the entire shelter providing approximately 26 lb/ft² (137kg/m²) of shielding. Further discussion of the radiation protection analysis is presented in Section 4.2.1.4. Food stored around the walls of the shelter is reached from the equipment bay. Floor panels are removed in the second deck to reach the food above the shelter, while ceiling panels of the fourth deck are removed to reach the food located beneath the shelter. As food is removed, the vacated area is filled with waste matter in order to maintain a nearly constant mass.

The equipment bay of this deck includes a storage area extending 2 feet (0.6m) inward from the outside wall and around the entire periphery. A passageway is provided between the equipment and the food storage compartment of the radiation shelter. The passageway is between 24 to 30 inches (0.6m to 0.8m) wide which should provide sufficient space for maintenance operations or removal of supplies even while operating in a pressure suit. Housed in the storage area are three 24 inch (0.6m) diameter water containers and positions for three other containers to be used for missions between 500 to 1000 days. Also included in the area is the major portion of the environmental control system equipment such as electrolysis unit, Bosch reactor and atmosphere control units, storage for spares and provisions for food, and spares storage for missions beyond 500 days.

The fourth deck of the crew compartment is comprised almost entirely of laboratories associated with the experiment program. These labs contain the necessary equipment to perform certain experiments, control the operation of all experiments, and process and store all experiment data. To accomplish these functions most effectively, the deck is divided into five separate labs. These include labs for optics, geophysics, electronics, bioscience, and science information center. Further discussion of these labs is presented in Section 4.2.2. Extending from the optics lab is a small 30-inch diameter airlock used to retrieve the mapping camera for film changing and maintenance.

Located centrally and in the ceiling is a pressure hatch leading to the combination radiation shelter/emergency pressure compartment. Also located centrally but in the floor is the pressure hatch leading to the airlock used for crew transfer to the MEM, logistics vehicles, or extra- vehicular activity operations. Beneath the floor of this deck and near the aft exit are located the automatic maneuvering units used for extra- vehicular activity (EVA) operations. Propellant for these units is replenished prior to entry into the crew compartment while oxygen and other expendables are replenished after entry.