Atomic Rockets

Consumables

How Much Oxygen?

If you want more data on life support than you know what to do with, try reading this NASA pdf document. Otherwise, read on.

For some great notes on spacecraft life support, read Rick Robinson's Rocketpunk Manifesto essay.

As a very rough rule of thumb: one human will need an amount of mass/volume equal to his berthing space for three months of consumables (water, air, food). This was figured with data from submarines, ISS, and Biosphere II. Of course this can be reduced a bit with hydroponics and a closed ecological system. This also makes an attractive option out of freezing one's passengers in cryogenic suspended animation.

Eric Rozier has an on-line calculator that will assist with calculating consumables.

Ken Burnsides and Eric Henry found the following information.

Assume that each person has a reserve of 10 liters of water, and somewhere between 0.1 and 0.25 liters of water per day to make up for reclamation losses. (Eric used 0.1, Ken used 0.25 mostly due to having worked in a sewage treatment plant)

There are two methods of cracking CO2 into C and O2: low energy and high energy.

Low energy requires prohibitive amounts of biomass in plants. Data from Biosphere II indicate roughly seven tons of plant life per person per day, with a need for roughly 4 days for a complete plant aspiration cycle, so call it 25 to 30 tons of plant per crewman. With an average density of 0.5, each ton of greenhouse takes up about 2 cubic meters (m3).

High energy methods take up much less space, but (as the name implies) requires inconveniently large amounts of energy. It also results in lots of messy by-products and waste heat. Practically, it is easier to flush the CO2 instead of cracking it, and instead bringing along an extra supply of water to crack for oxygen. Water is universally useful with a multitude of handy applications, and takes less energy to crack than CO2.

For future Mars missions, it has been suggested that the life support system should utilize the Sabatier Reaction. This takes in CO2 and hydrogen, and produces water and methane. The water can split by electrolysis into oxygen and hydrogen, with the oxygen used for breathing and the hydrogen used for another batch of CO2. Unfortunately the methane accumulates, and its production eventually uses up all the hydrogen. The reaction does require one atmosphere of pressure, a temperature of about 300°, and a catalyst of nickel or ruthenium on alumina.

According to NASA, each astronaut consumes approximately 0.8 kilograms (0.560 cubic meters) of oxygen per day. As a point of reference, a SCUBA tank is pressurized to about 250 bar i.e., 250 times atmospheric pressure. At that pressure, one person day of oxygen takes up about 0.00224 cubic meters.

Stored as liquid oxygen, 0.8 kilograms would take up about 0.0007 cubic meters. This requires extra mass for the cryogenic equipment to keep the oxygen liquid, but the volume savings are impressive.

So as far as pure oxygen goes, you take 0.8 kg for one person-day of oxygen, muliply it by the number of crewbeings on the ship, and then muliply it by the number of days in a standard mission (i.e., desired "endurance time" or time between supply stops) to discover the total oxygen mass requirement. Repeat with the volume figure for the total oxygen volume requirement.You'd be wise to add an additional reserve of about 25% to take account of pressurization of the hull, loss due to various mishaps, and general military paranoia.

However, this is just pure oxygen. This is insanely dangerous to use as the ship's atmosphere, the accident that killed the Apollo 1 crew proved that. In practice one uses a "breathing mix" of oxygen and another gas.

The Space Shuttle uses a 79% nitrogen/21% oxygen mix at atmospheric pressure (14.7 psi or 760 mm Hg). The shuttle space suits use 4.3 psi of pure oxygen, which means they have to prebreath pure oxygen while suiting up, or the bends will strike. Setting up the optimal breathable atmosphere is complicated.

For emergency use, it would be wise to pack away a few Oxygen Candles. These are composed of a compound of sodium chlorate and iron. When ignited, they smolder at about 600°C, producing iron oxide (rust), sodium chloride (salt), and approximately 6.5 man-hours of oxygen per kilogram of candle. Molecular Product's Chlorate Candle 33 masses 12.2 kilos, cylindrical can dimensions of 16 cm diameter x 29 height, burns for 50 minutes, and produces 3400 liters of oxygen.

How Much Food?

For food, Eric and Ken ran numbers from the USS Wyoming.

150 man crew, 90 day cruise, 31,500 kg of food (9,000 kg frozen, 18,000 kg dry, 4,500 kg fresh). This is about 2.3 kg of food per man per day.

Frozen meat has a density of about 0.35 and 0.4 (which Ken determined experimentally with a kilo of frozen meat in a 2 liter pitcher in his sink). Frozen veggies were less, so split the difference and use 0.375. 9,000 kg takes up 24,000 liters.

Fresh foods have a density of roughly 0.25, due to air packed around the food by the packaging. 4,500 kg takes up 18,000 liters.

Dry and canned goods range from densities of 0.25 for flour and bread and 1.0 for canned goods. Split the difference and use 0.5. 18,000 kilos takes up 36,000 liters.

Total volume is 78,000 liters, or 78 cubic meters of food (1000 liters = 1 m3). Assume that we're off on our calculations and round up to 80 m3 as a reserve.

Storage, including refrigeration wastage is usually three times the space, but the Navy has a tradition of doing things in amazingly tight quarters. So we will merely double it, for 160 m3 to store our food.

Add about 1000 liters of water (water for 150 crew for 90 days, plus a reserve) which of course masses 1000 kg.

Add about 3,500 liters of compressed air (0.2 liters per person per day for 90 days, plus a reserve for general pressurization and a 20% safety margin) which masses 1050 kg.

Together air and water add about 5 m3.

Alternate Figures

There are alternate figures on life support in this pdf document. It specifies the daily requirements of consumables per person as: 0.83 kg Oxygen, 0.62 kg freeze dried food (which would increase to 2.48 kg when the water was added), 3.56 kg water for drinking and food preparation, and 26.0 kg water for hygiene, flushing, laundry, dishes, and related matters. Note that the value for hygiene water is somewhat dependent on technology - if you have sonic showers and the like the requirements may be less.

William Seney notes that the NC State document specify oxygen consumption figures differ considerably from Eric and Ken's estimate. If we assume their value should be 48L per HOUR instead of per DAY (1.38 kg / day) it is much closer.

When the body uses glucose the reaction is:

C6H12O6 + 6 O2 => 6 CO2 + 6 H2O

so a slight excess of water is produced. According to the NC State document this works out to about 0.39L per person per day, which may be enough to replace losses.

Eeking Out

For a real Spartan bare-minimum cruise, you can probably use a figure of one m3 per person per day. But this would not be recommended for a cruise of longer than 20 to 30 days. Morale will suffer. And don't even think about feeding your crew food pills.

The bare-minimum of consumables mass looks like 0.98 kg water, 2.3 kg food, and 0.0576 kg air per person per day. About 3.3 kg total, round it up to 4. People actually need 2.72 kg of water, but since food is 75% water, it contains an additional 1.72 kgs.

Our 90 day cruise now has about 165 m3 of bare essentials. Put in niceties like better cooking gear, spare clothing, toilet paper, video games, soda, luxury goods, and you are probably getting close to 240 m3. That will fit in a sphere 8 meters in diameter (about 25 feet).

A useful accounting device is the "man-day" or "person-day". If your ship has 30 person-days of food and oxygen, it can support: 30 persons for 1 day (30 / 30 = 1), 15 persons for 2 days (30 / 15 = 2), 3 persons for 10 days (30 / 3 = 10), or one person for 30 days (30 / 1 = 30). By the same math, a ship with 30 person-days of supplies facing a 10 day mission could support 3 persons (30 / 10 = 3).

So if the exploration ship Arrow-Back becomes marooned in the trackless wastes of unexplored space and is listed as having 20 person-weeks of life support, it makes it really easy for Mr. Selfish to do the arithmetic and figure that he will survive for twenty weeks instead of one if he murders the other 19 crew members. More democratically, if the rescue ship will arrive in 8 days (1.14 weeks), one can calculate that the supplies will stretch for an extra day with 17 crew members (20 / 1.14 = 17.5, round down to 17). The crew draws straws, and the unlucky two who get the short straws have the opportunity to heroically sacrifice themselves so that the rest of the crew may live.

If the spacecraft has no artificial gravity, you'd better include lots of spices and hot sauce. As the body's internal fluids change their balance, crewmembers will get the equivalent of stuffy noses. This will decrease the sense of taste. Food will taste bland like it does when you have a head cold, and for the same reason.

You'll need more space if you want to include hydroponics for fresh veggies. Roughly 800 liters of hydroponics per person per 'green meal' per week. This also helps CO2 scrubbing and crew moral. About 20 m3 per 25 men, or 120 m3 for our 150 man crew. 3 green meals per week takes about 600 m3.

Closed Ecological Systems

Spirulina

In THE MILLENNIAL PROJECT, Marshall Savage sings the praises of Spirulina algae. However, you'd best take the following with a grain of salt. There is often a long distance between the ideal and the real.

Anyway, Spirulina is apparently almost the perfect food, nutritional wise. A pity it tastes like green slime (though Savage maintains that genetic engineering can change the flavor). Spirulina is highly digestible since it contains no cellulose. It is 65% protein by weight and contains all eight essential amino acids in quantities equivalent to meat and milk. It also has almost all the vitamins, with the glaring exception of vitamin C (I guess rocketmen will become "limeys" again). It is also a little sparse on carbohydrates. Savage calculates that it will be possible to achieve production rates of 100 grams (dry weight) of algae per liter of water per day. It breaks down 6 liters of algae water per person, supplying both food and oxygen, while consuming sunlight (or grow-lights), CO2 and sewage. 6 liters of algae water will produce 600 grams of "food" (540 grams is 2500 calories, an average daily food requirement), 600 liters of oxygen, and consume 720 liters of CO2 and an unspecified amount of nutrient salts extracted from sewage. Since food is generally 75% water, 600 grams of dry food will convert into about 2.4 kg of moist food, which compares favorably with the 2.3 kg on the USS Wyoming.

NASA commissioned a study (PDF file) back in 1988 to determine how difficult it would be to cultivate Spirulina as part of a closed ecological life support system.

Dr. John Schilling mentions a possible pitfall:

[Spirulina is] [h]igh in nucleic acid, which means you can only eat about fifty grams per day or you're at risk of gout. And it's going to be really, really, really embarassing if you have to list "gout" as the cause of failure for a space mission.

Dr. John Schilling

There are other things you have to be mindful of when cultivating Spirulina. From the Swedish Medical Center:

Various forms of blue-green algae can be naturally contaminated with highly toxic substances called microcystins.

Some states, such as Oregon, require producers to strictly limit the concentration of microcystins in blue-green algae products, but the same protections cannot be assumed to have been applied to all products on the market. Furthermore, the maximum safe intake of microcystins is not clear, and it is possible that when blue-green algae is used for a long time, toxic effects might build up...

...Blue-green algae can also contain a different kind of highly toxic substance, called anatoxin (ed note: AKA "Very Fast Death Factor").

In addition, when spirulina is grown with the use of fermented animal waste fertilizers, contamination with dangerous bacteria could occur. There are also concerns that spirulina might concentrate radioactive ions found in its environment. Probably of most concern is spirulina's ability to absorb and concentrate heavy metals such as lead and mercury if they are present in its environment. One study of spirulinas grown in a number of locations found them to contain an unacceptably high content of these toxic metals. However, a second study on this topic claims that the first used an unreliable method of analyzing heavy metal content, and concludes that a person would have to eat more than 77 g daily of the most heavily contaminated spirulina to reach unsafe mercury and lead consumption levels.

These researchers, however, go on to suggest that it is not prudent to eat more than 50 g of spirulina daily. The reason they give is that the plant contains a high concentration of nucleic acids, substances related to DNA. When these are metabolized, they create uric acid, which could cause gout or kidney stones. This is of special concern to those who have already had uric acid stones or attacks of gout.

SF writers with an evil turn of mind will see some interesting plot possibilites in these facts. The ship's food supply could become contaminated by an incompetent repair of the algae system utilizing lead pipes, an algae culture supplier with poor quality control, or deliberate sabotage.

Algae Tankage

The advantage of algae is that it can theoretically form a closed ecological cycle. This means that 6 liters of algae water, one human, some equipment, and sunlight can keep the human supplied with food and oxygen forever. Theoretically, of course. 0.006 m3 per person compared to 90 m3 per person is a strong argument for lots of green slime dinners for enlisted Solar Guard rocketmen. (Astro once said "I've been eating those synthetic concentrates so long my stomach thinks I've been turned into a test tube") Of course the Biosphere II fiasco shows how far we are from actually achieving a closed ecological cycle. Don't forget the 0.25 liters of water per person per day to make up for reclamation losses.

William Seney points out that as a luxury, some of the algae can be diverted to feed fish such as carp, catfish or tilapia for an occasional treat.

And you'd better keep the algae tanks far from the atomic drive. The last thing you want is for the little green darlings to mutate into something you can't eat. Or worse: something that is really inefficient at producing oxygen.

Christopher Huff begs to differ:

Actually, the algae tanks would make pretty good radiation shielding. "Clean" cultures of the original strain of algae would be easy to carry along to replenish the main tanks if an inedible form did take hold...just stick some packets of dry spores in the radiation shelter. As for the last possibility, a strain that was poor at conversion of CO2 would quickly be out-bred by the better strains. With algae constantly being removed for food, it would quickly be eliminated from the system.

Also, in addition to fish, a small colony of shrimp or crabs could be fed off the algae, providing a bit more variety in the food supply. Clams could also have a place, providing a useful sink for calcium, carbon, and oxygen in their shells as well as helping to process water. A combination of fresh and salt water systems might work out best.

Christopher Huff

There were some figures in a report on a cruder life-support set up written in 1953. This used Chlorella algae, which isn't quite as good as Spirulina since it has an indigestible cellulose cell wall. The figures assume a Chlorella culture density of 55 grams per liter of water and a daily yield of 2.5 grams per liter. Savage's 100 grams per liter sounds a little optimistic, and 2.5 sounds a little pessimistic. The truth is probably somewhere in between.

At a yield of 2.5 g/l, to provide one rocketeer with 500 grams of food (instead of Savage's 600 grams) will require 200 liters of algae culture.

Urine is passed through an absorption tube to remove excess salt (which would kill the algae) but retaining urea and other nitrogen compounds the algae needs. Faeces are irradiated with ultraviolet to kill all bacteria and added to the urine. This is fed to the main algae tank along with pressurized carbon dioxide (previously removed from the air with calcium oxide). A pump sends a flow of algae culture to the growth trays under filtered sunlight. The culture then passes through a centrifugal separator on its way back to the main tank. The separator performs two functions: [1] removing excess gas to maintain a pressure equilibrium with the carbon dioxide injection and [2] periodically harvesting algae for food. Harvest will occur once a day, extracting 500 grams of algae from nine liters of culture per person. The pump will be controlled such that the algae on the average will experience two minutes of sunlight then three minutes in the darkness of the main tank before it starts the cycle anew.

A fresh batch of urine and faeces is added immediately after algae harvest, to give the algae twenty four hours to consume it. So by next harvest there is no human excretions contaminating the food (you hope).

Now for the answer you've been waiting for. Dr. Bowman estimates that the equipment will mass approximately 50 kg, plus 200 kg per man for algae culture. Since the equipment is such a small fraction of the total, mass savings depend upon getting the algae yield higher than 2.5 g/l. Such as Savage's 100 g/l Spirulina with 6 kg per man of algae culture.

Dr. Bowman points out that when one compares an algae system with merely stocking crates of food, the break-even point occurs at a mission of 145 days (about five months). Below this time it takes less mass to bring crates of food, as the mission duration rises above 145 days the algae tanks get more and more attractive.

You can find more interesting reading on the topic of life support here.

In NASA jargon, a closed environment life support system based on algae is called a "yoghurt box", one based on hydroponic leafy plants is called a "salad machine", and one based on a fish farm is called a "sushi maker".

Supercritical Water Oxidation

How much does the equipment mass? Savage is a little sparse on details there. Waste products from the astronaut's septic tanks are run through a "Supercritical water oxidation" unit that burns everything into simple oxidized chemicals (like carbon dioxide, water, and nitrous oxide) and some mineral ash. The appropriate chemicals are fed to the Spirulina., which multiplies in meters of transparent tubes run under filtered sunlight. Filtered because raw sunlight in outer space is quite deadly to algae, and it isn't too healthy for humans either. Anyway I could find no figures on the mass of a SWO unit or the rest.

How does the SWO unit work?

Water is pretty near the universal solvent at room temperature. Heat it to quite high temperatures, under fairly high pressure so that it doesn't boil, and it gets, uh, more so. Dissolve a bit of oxygen in it, and you have a fantastically corrosive witches' brew that will vigorously attack almost anything. Throw in just about any organic substance you care to name, and out comes water, CO2, nitrogen, and sterile ash (oxides of metals, mostly). One of the bigger practical problems, in fact, is making the equipment stand up to it. The other major problem is that it's pretty power-intensive, because of the high temperature and high pressure.

It's pretty much the preferred way to recycle organic wastes -- kitchen garbage, human wastes, etc. -- in designs for advanced closed-cycle life-support systems.

Henry Spencer

There is more information on SWO units here. The first reference describes a facility with a volume of just over 20 cubic metres that can process 7.5L per minute, more than enough for a crew of 300. (30L/person/day - 20 hours a day). Thanks to William Seney for these link.

General Atomics has some developed some SWO units for waste disposal.

Meat

Other SF novels have suggested vats of yeast or tissue cultures of meat ("carniculture") to supplement food supplies. But unless they can re-cycle wastes from the crew, it seems more efficient to just carry more boxed food. Currently scientist can only grow tissue cultures as a single sheet of cells, making them thicker will require figuring out how to make them grow blood vessels to nourish all the cells. But some technicians figure that they can grow lots of meat cell sheets, then laminate the sheet layers together to approximate a slab of meat.

If you are trying a closed cycle with tissue cultures, you will have to deal with the problem of the Food Chain. Typically each higher level of the pyramid has one-tenth the biomass of the one below, for reasons you can read about in the link. What this means is that you will have to feed ten meals worth of algae to the meat tissue culture in order to produce one meal worth of meat. Even on Terra, this is the reason why meat is more expensive than vegetables.

Obviously the food chain effect also applies to diverting some of the algae to fatten up some fish as a special meal.

Arielle went to bed, too, but first she stopped off at the sick bay to get patches for her cracked fingernails, then at the galley to get a bite to eat. She had a double helping of protocheese with real garlic from Nels's hydroponic gardens, two algae shakes with energy sticks mixed in for crunch, then, still hungry, she finished with a desert consisting of a half-pound of white-meat sticks from "Chicken Little" -- her real-meat ration for a week -- sliced into thin strips and hot-cooked with James's secret recipe of herbs and spices.

From ROCHEWORLD by Robert L. Forward. (1990)

"Chicken Little" is a chicken breast meat tissue culture.

Yeast

A shmoo is a fictional cartoon creature created by Al Capp, they first appeared in his classic comic strip Li'l Abner in 1948. Shmoos were prolific, required no food (only air), are delicious and nutritious, have no bones or other waste, and are eager to be eaten. (Ironically, they are the greatest menance to humanity ever known. Not because they are bad, but because they are good.)

Oddly enough, shmoos share many common traits with one-celled yeast. Yeast even looks a little like a shmoo. When a yeast cell senses the mating pheromone, it initiate polarized growth towards the mating partner, creating the characteristic outline of a shmoo. The process is called "shmooing", which shows that biologists have a sense of humor. As to the matter of the deliciousness of yeast, see the exerpt from Lucky Starr and the Oceans of Venus below.

The science fiction version of a shmoo is a Frumious Bandersnatch, from Larry Niven's "Known Space" series.

Lucky smiled and went on, "Venus is a fairly developed planet. I think there are about fifty cities on it and a total population of six million. Your exports are dried seaweed, which I am told is excellent fertilizer, and dehydrated yeast bricks for animal food."

"Still fairly good," said Morriss. "How was your dinner at the Green Room, gentlemen?"

Lucky paused at the sudden change of topic, then said, "Very good. Why do you ask?"

"You'll see in a moment. What did you have?"

Lucky said, "I couldn't say, exactly. It was the house meal. I should guess we had a kind of beef goulash with a rather interesting sauce and a vegetable I didn't recognize. There was a fruit salad, I believe, before that and a spicy variety of tomato soup."

Bigman broke in. "And jelly seeds for dessert."

Morriss laughed hootingly. "You're all wrong, you know," he said. "You had no beef, no fruit, no tomatoes. Not even coffee. You had only one thing to eat. Only one thing. Yeast!"

"What?" shrieked Bigman.

For a moment Lucky was startled also. His eyes narrowed and he said, "Are you serious?"

"Of course. It's the Green Room's specialty. They never speak of it, or Earthmen would refuse to eat it. Later on, though, you would have been questioned thoroughly as to how you liked this dish or that, how you thought it might have been improved, and so on. The Green Room is Venus's most valuable experimental station."

"I am guessing," said Lucky, "that yeast has some connection with the crime wave on Venus."

"Guessing, are you?" said Morriss, dryly. "Then you haven't read our official reports. I'm not surprised. Earth thinks we are exaggerating here. I assure you, however, we are not. And it isn't merely a crime wave. Yeast, Lucky, yeast! That is the nub and core of everything on this planet."

For a moment they sipped in silence; then Morriss said, "Venus, Lucky, is an expensive world to keep up. Our cities must make oxygen out of water, and that takes huge electrolytic stations. Each city requires tremendous power beams to help support the domes against billions of tons of water. The city of Aphrodite uses as much energy in a year as the entire continent of South America, yet it has only a thousandth the population.

"We've got to earn that energy, naturally. We've got to export to Earth in order to obtain power plants, specialized machinery, atomic fuel, and so on. Venus's only product is seaweed, inexhaustible quantities of it. Some we export as fertilizer, but that is scarcely the answer to the problem. Most of our seaweed, however, we use as culture media for yeast, ten thousand and one varieties of yeast."

Morriss looked soberly at the small Martian and said, "If you wish. Bigman is quite correct in his low opinion of yeast in general. Our most important strains are suitable only for animal food. But even so, it's highly useful. Yeast-fed pork is cheaper and better than any other kind. The yeast is high in calories, proteins, minerals, and vitamins.

"We have other strains of higher quality, which are used in cases where food must be stored over long periods and with little available space. On long space journeys, for instance, so-called Y-rations are frequently taken.

"Finally, we have our top-quality strains, extremely expensive and fragile growths that go into the menus of the Green Room and with which we can imitate or improve upon ordinary food. None of these are in quantity production, but they will be someday. I imagine you see the whole point of all this, Lucky."

"I think I do."

"I don't," said Bigman belligerently.

Morriss was quick to explain. "Venus will have a monopoly on these luxury strains. No other world will possess them. Without Venus's experience in zymoculture.

"In what?" asked Bigman.

"In yeast culture. Without Venus's experience in that, no other world could develop such yeasts or maintain them once they did obtain them. So you see that Venus could build a tremendously profitable trade in yeast strains as luxury items with all the galaxy. That would be important not only to Venus, but to Earth as well- to the entire Solar Confederation. We are the most over-populated system in the Galaxy, being the oldest. If we could exchange a pound of yeast for a ton of grain, things would be well for us."

From Lucky Starr and the Oceans of Venus by Paul French (Isaac Asimov)(1954)

How Space Kills You

A NASA technician said "If you treat vacuum as you would poison gas you won't go far wrong."

How does space kill you? Let me count the ways. Face it, the human body was not designed to properly function in the vacuum of space. At a rough guess a person can survive space exposure as long as they are placed back inside a pressured atmosphere within 90 seconds. After that time, death might be unavoidable. You will only have about ten seconds before you become unconscious. Dr. Geoffrey Landis has an analysis here. There are some more links on the topic of explosive decompression here.

And anybody who's seen 2001 A Space Odyssey knows that a human exposed to vacuum is not going to pop like a balloon.

In order of lethality the effects are:

Ebullism
Formation of gas bubbles in bodily fluids by reduction of environmental pressure aka your blood starts to boil. Your eyes and mouth freeze due to evaporative cooling, tissue dies with loss of oxygen, entire body swells enormously, circulatory failure, muscle failure due to flaccid paralysis, lungs collapse and fill with ice.
Hypoxia
The body being deprived of adequate oxygen supply aka there ain't nothing to breath in space. Ataxia, confusion, disorientation, hallucinations, behavioral change, severe headaches, reduced level of consciousness, papilloedema, breathlessness, pallor, tachycardia, pulmonary hypertension, cyanosis, bradycardia, cor pulmonale, low blood pressure, death
Hypocapnia
A state of reduced carbod dioxide in the blood aka turbocharged hyperventilation. Transient dizziness, visual disturbances, anxiety, pins and needles sensation, muscle cramps and tetany in hands and feet.
Decompression Sickness
Dissolved gases coming out of solution into bubbles inside the body on depressurisation aka turn your blood stream into red foam like a shaken can of soda pop. Symptoms may range from rash to agonizing joint paint to death.
Extreme Temperature Variations
In sunlight at Terra's orbit the body may overheat, in shadow the body can lose heat at a rate of up to 1,000 watts.
Radiation
Prolonged exposure to ultraviolet, x-rays, and energized protons can cause death by organ failure, short-term exposure may cause cancer.

We've had our expected quota of minor industrial accidents. Cuts, bruises, contusions, a few broken bones, some cases of exhaustion because a rigger worked beyond his limits in vacuum and zero-g, a couple of burns, but nothing really serious until we ran into "vac bite."

The safety compartmentalization of the P-suits hasn't always been a safety measure, although it's undoubtedly saved many lives from traumatic abaryia (sudden loss of all pressure in one's space suit). Nobody thought about secondary effects. The cuff latch on a man's glove jailed yesterday, and the glove blew away. "Vac bite"—which is what we're calling it colloquially until I can figure out a suitable Greco-Latin term —is the result of exposure of the extremities to vacuum conditions.

The extremity—hand, foot, arm, etc.—doesn't explode; connective tissue's strong and the human skin's remarkably tough. But the extremity swells up in the Kittinger Syndrome, first experienced by Captain Joseph Kittinger during a stratospheric parachute jump back in 1960. The absence of atmospheric pressure causes vasodilation and edema, which becomes very painful. The swelling also inhibits movement. If the abaryic condition prevails for several minutes, it can cause aneurism and rupture of the capillary walls followed by hematomas. Unless there's a cut or other opening in the skin, there's little chance of blood loss. But if the abaryic condition continues, tissue's destroyed. The course of the affliction begins to parallel that of frostbite, which is the reason it got its vernacular name. It's painful as hell and immobilizes the extremity. Right now, the only way we know to treat it is with cold packs or hypothermic immersion, along with analgesics and mild diuretics. I'm thinking about the possibility of trying a hyperbaric chamber, but we haven't got one here yet. Maybe in a year or so.

No bends yet. Everyone flushes the nitrogen out of his system for thirty minutes by breathing pure Oh-two before cycling into vacuum. But if there were an explosive decompression of any of the living spaces in GEO Base or with my paramedics on an emergency, we'd get bends because we're running an oxynitrogen atmosphere.

From Space Doctor by Lee Correy (G. Harry Stine) 1981
And That's Just How We Like It

Space will kill you in any number of ways. So, in fact, will most planets that aren’t your homeworld or close copies of it.

Simple risks will kill you, if you don’t keep a weather eye on them. Radiation, vacuum, dioxide, heat. Leaks, breakdowns, inefficiencies. Not paying attention to where your air and water and other things that just magically exist for the taking downside come from, that’ll kill you, too. Carelessness, inattention, expediency, pragmatism, shortcut-taking, an excessively casual approach to maintenance procedures — all things that bring an automatic death sentence at the hands of the uncaring, pedantic universe. Incompetence, determined ignorance, and native stupidity, even more so. And indulging one’s fond delusions about the nature of reality, that’ll kill you fastest of all.

These are the reasons why many sensible people from many sensible civilizations choose not to go there.

The people who scattered habs across the entire system from Oculus to Farside, from Eurymir to Galine, from corona-scraping Salamandrine to lonely Blackwatch, on the other hand, considered these things advantages.

— introduction to Tin Cans and Checklists: The Early Days, by Aithne Silverfall

"You know what the folks back home don't understand, the ones who've never left Earth, is just how dangerous space can be. Aside from incidents like this, just the everyday reality of living your days and nights in a big tin can surrounded by a vacuum."

"I remember my first time on a transport, on the Moon-Mars run. I was just a kid, maybe seventeen. A buddy of mine was messing around, and zipping through the halls, and he hid in one of the airlocks. I don't know, I guess he was gonna try to scare us or something, I don't know... But just as I got close, he must have hit the wrong button because the air doors slammed shut, the space doors opened, and he... just flew out into space."

"And the one thing they never tell you is that you don't die instantly in vacuum. He just hung there against the black like a puppet with his strings all tangled up... or one of those old cartoons where you run off the edge of the cliff and your legs keep going."

"You could see that he was trying to breathe, but there was nothing. The one thing I remember when they pulled in his body... his eyes were frozen."

"A lot of people make jokes about spacing somebody, about shoving somebody out an airlock -- I don't think it's funny. Never will."

From Babylon 5: "And Now For A Word". Dr. Franklin relates a tragic experience.

"Pegasus to Acheron," he replied. "I have three hundred passengers aboard. I cannot hazard my ship if there is danger of an explosion."

"There is no danger, I can guarantee that. We will have at least five minutes' warning, which will give us ample time to get clear of you."

"Very well—I'll get my airlocks ready and my crew standing by to pass you a line."

There was a pause longer than that dictated by the sluggish progress of radio waves. Then Brennan replied: "That's our trouble. We're cut off in the forward section. There are no external locks here, and we have only five suits among a hundred and twenty men."

Halstead whistled and turned to his navigating officer before answering.

"There's nothing we can do for them," he said. "They'll to crack the hull to get out, and that will be the end of everyone exceed the five men in the suits. We can't even lend them our own suits—there'll be no way we can get them aboard without letting down the pressure." He flicked over microphone switch.

"Pegasus to Acheron. How do you suggest we can assist you?" It was eerie to be speaking to a man who was already as good as dead. The traditions of space were as strict as those of the sea. Five men could leave the Acheron alive, but her captain would not be among them.

Halstead did not know that Commodore Brennan had other ideas, and had by no means abandoned hope, desperate though the situation on board the Acheron seemed. His chief medical officer, who had proposed the plan, was already explaining it to the crew.

"This is what we're going to do," said the small, dark man who a few months ago had been one of the best surgeons on Venus. "We can't get at the airlocks, because there's vacuum all round us and we've only got five suits. This ship was built for fighting, not for carrying passengers, and I'm afraid her designers had other matters to think about besides Standard Spaceworthiness Regs. Here we are, and we have to make the best of it.

"We'll be alongside the Pegasus in a couple of hours. Luckily for us, she's got big locks for loading freight and passengers there's room for thirty or forty men to crowd into them, if they squeeze tight—and aren't wearing suits. Yes, I know that sounds bad, but it's not suicide. You're going to breathe space, and get away with it! I won't say it will be enjoyable, but it will be something to brag about for the rest of your lives.

"Now listen carefully. The first thing I've got to prove to you is that you can live for five minutes without breathing—in fact, without wanting to breathe. It's a simple trick: Yogis and magicians have known it for centuries, but there's nothing occult about it and it's based on common-sense physiology. To give you confidence, I want you to make this test."

The M. O. pulled a stop watch out of his pocket, ad continued: "When I say 'Now!' I want you to exhale completely—empty your lungs of every drop of air—and then see how long you can stay before you have to take a breath. Don't strain—just hold out until it becomes uncomfortable, then start breathing again normally. I'll start counting the seconds after fifteen, so you can tell what you managed to do. If anyone can't take the quarter minute, I'll recommend his instant dismissal from the Service."

The ripple of laughter broke the tension, as it had been intended to; then the M. O. held up his hand, and swept it down with a shout of "Now!" There was a great sigh as the entire company emptied its lungs; then utter silence.

When the M. O. started counting at "Fifteen," there were a few gasps from those who had barely been able to make the grade. He went on counting to "Sixty" accompanied by occasional explosive pants as one man after another capitulated. Some were still stubbornly holding out after a full minute, "That's enough," said the little surgeon. "You tough guys can stop showing off, you're spoiling the experiment."

Again there was a murmur of amusement; the men were rapidly regaining their morale. They still did not understand what was happening, but at least some plan was afoot that offered them a hope of rescue.

"Let's see how we managed," said the M. O. "Hands up all those who held out for fifteen to twenty seconds…Now twenty to twenty-five…Now twenty-five to thirty—Jones, you're a damn liar—you folded up at fifteen!—Now thirty to thirty-five… When he had finished the census, it was clear that more than half the company had managed to hold their breath for thirty seconds, and no one had failed to reach fifteen seconds.

"That's about what I expected," said the M. O. "You can regard this as a control experiment, and now we come on to the real thing. I ought to tell you that we're now breathing almost pure oxygen here, at about three hundred millimeters. So although the pressure in the ship is less than half its sea-level value on Earth, your lungs are taking in twice as much oxygen as they would on Earth, and still more than they would on Mars or Venus. If any of you have sneaked off to have a surreptitious smoke in the toilet, you'll already have noticed that the air was rich, as your cigarette will only have lasted a few seconds.

"I'm telling you all this because it will increase your confidence to know what is going on. What you're going to do now is to flush out your lungs and fill your system with oxygen. It's called hyperventilation, which is simply a ten dollar word for deep breathing. When I give the signal, I want you all to breathe as deeply as you can, then exhale completely, and carry on breathing in the same way until I tell you to stop. I'll tell you do it for a minute; some of you may feel a bit dizzy at the end of that time, but it'll pass. Take in all the air you can with every breath; swing your arms to get maximum chest expansion.

"Then, when the minute's up, I'll tell you to exhale, then stop breathing, and I'll begin counting seconds again. I think I can promise you a big surprise. O. K.—here we go!"

For the next minutes, the overcrowded compartments of the Acheron presented a fantastic spectacle. More than a hundred men were flailing their arms and breathing stertorously, as if each was at his last gasp. Some were too closely packed together to breathe as deeply as they would have liked, and all had to anchor themselves somehow so that their exertion would not cause them to drift around the cabins.

"Now!" shouted the M. O. "Stop breathing—blow out all your air—and see how long you can manage before you've got to start again. I'll count the seconds, but this time I won't begin until half a minute has gone."

The result, it was obvious, left everyone flabbergasted. One man failed to make the minute, otherwise almost two minutes elapsed before most of the men felt the need to breathe again. Indeed, to have taken a breath before then would have demanded a deliberate effort. Some men were still perfectly comfortable after three or four minutes; one was holding out at five when the doctor stopped him.

"I think you'll all see what I was trying to prove. When your lungs are flushed out with oxygen, you just don't want to breathe for several minutes, any more than you want to eat again after a heavy meal. It's no strain or hardship; it's not a question of holding your breath. And if your life depended on it, you could do even better than this, I promise you.

"Now we're going to tie up right alongside the Pegasus; it will take less than thirty seconds to get over to her. She'll have her men out in suits to push along any stragglers, and the air lock doors will be slammed shut as soon as you're all inside. Then the lock will be flooded with air and you'll be none the worse except for some bleeding noses."

He hoped that was true. There was only one way to find out. It was a dangerous and unprecedented gamble, but there was no alternative. At least it would give every man a fighting chance for his life.

"Now," he continued, "you're probably wondering about the pressure drop. That's the only uncomfortable part, but you won't be in a vacuum long enough for severe damage. We'll open the hatches in two stages; first we'll drop pressure slowly to a tenth of an atmosphere, then we'll blow out completely in one bang and make a dash for it. Total decompression's painful, but not dangerous. Forget all that nonsense you may have heard about the human body blowing up in a vacuum. We're a lot tougher than that, and the final drop we're going to make from a tenth of an atmosphere to zero is considerably less than men have already stood in lab tests. Hold your mouth wide open and let yourself break wind. You'll feel your skin stinging all over, but you'll probably be too busy to notice that."

The M. O. paused, and surveyed his quiet, intent audience. They were all taking it very well, but that was only to be expected. Every one was a trained man—they were the pick of the planets' engineers and technicians.

"As a matter of fact," the surgeon continued cheerfully, "you'll probably laugh when I tell you the biggest danger of the lot. It's nothing more than sunburn. Out there you'll be in the sun's raw ultra-violet, unshielded by atmosphere. It can give you a nasty blister in thirty seconds, so we'll make the crossing in the shadow of the Pegasus. If you happen to get outside that shadow, just shield your face with your arm. Those of you who've got gloves might as well wear them.

"Well, that's the picture. I'm going to cross with the first team just to show how easy it is. Now I want you to split up into four groups, and I'll drill you each separately."

Side by side, the Pegasus and the Acheron raced toward the distant planet that only one of them would ever reach. The airlocks of the liner were open, gaping wide no more than a few meters from the hull of the crippled battleship. The space between the two vessels was strung with guide ropes, and among them floated the men of the liner's crew, ready to give assistance if any of the escaping men were overcome during the brief but dangerous crossing.

It was lucky for the crew of the Acheron that four pressure bulkheads were still intact. Their ship could still be divided into four separate compartments, so that a quarter of the crew could leave at a time. The airlocks of the Pegasus could not have held everyone at once if a mass escape had been necessary.

Captain Halstead watched from the bridge as the signal given. There was a sudden puff of smoke from the hull of the battleship, then the emergency hatch—certainly never designed for an emergency such as this—blew away into space. A cloud of dust and condensing vapor blasted out, obscuring the view for a second. He knew how the waiting men would feel the escaping air sucking at their bodies, trying to tear them away from their handholds.

When the cloud had dispersed, the first men had already emerged. The leader was wearing a spacesuit, and all the others were strung on the three lines attached to him. Instantly, men from the Pegasus grabbed two of the lines and darted off to their respective airlocks. The men of the Acheron, Halstead was relieved to see, all appeared to be conscious and to be doing everything they could to help.

It seemed ages before the last figure on its drifting line was towed or pushed into an airlock. Then the voice from one of those spacesuited figures out there shouted, "Close Number Three!" Number One followed almost at once; but there was an agonizing delay before the signal for Two came. Halstead could not see what was happening; presumably someone was still outside and holding up the rest. But at last all the locks were closed. There was no time to fill them in the normal way; valves were jerked open by brute force and the chambers filled with air from the ship.

Aboard the Acheron, Commodore Brennan waited with remaining ninety men, in the three Compartments that were unsealed. They had formed their groups and were strung in chains of ten behind their leaders. Everything had been planned and rehearsed; the next few seconds would prove whether or not in vain.

Then the ship's speakers announced, in an almost quietly conversational tone: Pegasus to Acheron. We've got all your men out of the locks. No casualties. A few hemorrhages. Give us five minutes to get ready for the next batch."

They lost one man on the last transfer. He panicked and they had to slam the lock shut without him, rather than risk the lives of all the others. It seemed a pity that they could not all have made it, but for the moment everyone was too thankful to worry about that.

From Earthlight by Sir Arthur C. Clarke (1955)

McAndrew stood at the outer lock, ready to open it. I pulled the whistle from the lapel of my jacket and blew hard. The varying triple tone sounded through the lock. Penalty for improper use of any Sturm Invocation was severe, whether you used spoken, whistled, or electronic methods. I had never invoked it before, but anyone who goes into space, even if it is just a short trip from Earth to Moon, must receive Sturm vacuum survival programming. One person in a million uses it. I stood in the lock, waiting to see what would happen to me.

The sensation was strange. I still had full command of my movements, but a new set of involuntary activities came into play. Without any conscious decision to do so I found that I was breathing hard, hyper-ventilating in great gulps. My eye-blinking pattern had reversed. Instead of open eyes with rapid blinks to moisten and clean the eyeball, my lids were closed except for brief instants. I saw the lock and the space outside as quick snapshots.

The Sturm Invocation had the same effect an McAndrew, as his own deep programming took over for vacuum exposure. When I nodded, he swung open the outer lock door. The air was gone in a puff of ice vapor. As my eyes flicked open I saw the capsule at the top of the landing tower. To reach it we had to traverse sixty meters of the interstellar vacuum. And we had to carry Sven Wicklund's unconscious body between us.

For some reason I had imagined that the Sturm vacuum programming would make me insensitive to all pain. Quite illogical, since you could permanently damage your body all too easily in that situation. I felt the agony of expansion through my intestines, as the air rushed out of all my body cavities. My mouth was performing an automatic yawning and gasping, emptying the Eustachian tube to protect my ear drums and delicate inner ear. My eyes were closed to protect the eyeballs from freezing, and open just often enough to guide my body movements.

Holding Wicklund between us, McAndrew and I pushed off into the open depths of space. Ten seconds later, we intersected the landing tower about twenty meters up. Sturm couldn't make a human comfortable in space, but he had provided a set of natural movements that corresponded to a zero-gee environment. They were needed. If we missed the tower there was no other landing point within light-years.

The metal of the landing tower was at a temperature several hundred degrees below freezing. Our hands were unprotected, and I could feel the ripping of skin at each contact. That was perhaps the worst pain. The feeling that I was a ball, over-inflated and ready to burst, was not a pain. What was it? That calls for the same sort of skills as describing sight to a blind man. All I can say is that once in a lifetime is more than enough.

Thirty seconds in the vacuum, and we were still fifteen meters from the capsule. I was getting the first feeling of anoxia, the first moment of panic. As we dropped into the capsule and tagged shut the hatch I could feel the black clouds moving around me, dark nebulae that blanked out the bright star field.

The transfer capsule had no real air lock. When I hit the air supply, the whole interior began to fill with warm oxygen. As the concentration grew to a perceptible fraction of an atmosphere, I felt something turn off abruptly within me. My eye blinking went back to the usual pattern, my mouth closed instead of gaping and gasping, and the black patches started to dwindle and fragment.

From "All the Colors of the Vacuum" by Charles Sheffield (1981)

Artist Nathan Hoste is doing a well-researched series called Bodies in Space on all the damage space does to an unprotected human. Warning, images may be considered NSFW.

Air

Pressure

You can see why some spacecraft opt for an internal atmosphere with lower than Terra-normal pressure, increasing the percentage of oxygen to compensate. The lower the pressure, the slower the air will escape through a meteor hole. NASA uses Terra-normal pressure (14.7 psi) inside the Space Shuttle, but only 0.29 pressure (4.5 psi) with pure oxygen in the space suits. According to NASA, an astronaut wearing a Shuttle space suit can survive 22 minutes with a 1/8" hole.

This does raise a new problem. There is a chance that the high-oxygen atmosphere will allow a meteor to ignite a fire inside the suit. There isn't a lot of research on this, but NASA seems to think that the main hazard is a fire enlarging the diameter of the breach, not an astronaut-shaped ball of flame.

The increased fire risk is one reason why NASA isn't fond of low-pressure/high oxygen atmospheres in the spacecraft proper. There are other problems as well, the impossibility of air-cooling electronic components and the risk of long-term health problems being two.Setting up the optimal breathable atmosphere is complicated.

A more annoying than serious problem with low pressure atmospheres is the fact that they preclude hot beverages and soups. It is impossible to heat water to a temperature higher than the local boiling point. And the lower the pressure, the lower the boiling point. You may have seen references to this in the directions on certain packaged foods, the "high altitude" directions. The temperature can be increased if one uses a pressure cooker, but safety inspectors might ask if it is worth having a potentially explosive device onboard a spacecraft just so you can have hot coffee.

The Bends

Decompression sickness (also known as DCS, divers' disease, the bends or caisson disease) is one of the more hideous dangers of living in space.

It occurs when a person has been breathing an atmosphere containing inert gases (generally nitrogen or helium) and they move into an environment with lower pressure. This is commonly when they put on a soft space suit or the room suffers an explosive decompression.

It has all sorts of nasty effects, ranging from joint pain and rashes to paralysis and death. The large joints can suffer deep pain from mild to excruciating. Skin can itch, feel like tiny insects are crawling all over, mottling or marbling, swell, and/or suffer pitting edema. The brain can have sudden mood or behavior changes, confusion, memory loss, hallucinations, seizures, and unconsciousness. The legs can become paralyzed. Headache, fatigue, malaise, loss of balance, vertigo, dizziness, nausea, vomiting, hearing loss, shortness of breath, and urinary or fecal incontinence: the list just goes on and on.

Why does it happen? Well, imagine a can of your favorite carbonated soda beverage. Shake it up, and nothing happens. But when you open it, the soda explodes into foam and sprays everywhere. When you open the container of shaken soda, you lower the pressure on the soda fluid. This allows all the dissolved carbon dioxide in the soda to un-dissolve, creating zillions of carbon dioxide bubbles, forming a foam.

Now imagine that the carbon dioxide is nitrogen, the drink is the poor astronaut's blood in their circulatory system, and the foam is the deadly arterial gas embolisms. That's what causes the bends.

Please note that sometimes the bends can occur if one moves from one habitat to another that has the same pressure, but a different ratio of breathing mix (the technical term is "Isobaric counterdiffusion"). Spacecraft of different nations or models could use different breathing mixes, beware. In fact, rival astromilitaries might deliberately utilize odd-ball breathing mixes, to make life difficult for enemy boarding parties invading their ships.

The bends can be prevented by slow decompression, and by prebreathing. Or by breathing an atmosphere containing no inert gases. Slow decompression works great for deep-sea divers but NASA does not favor it for space flight. An atmosphere with no inert gases (pure oxygen) is an insane fire risk. NASA does not allow a pure oxygen atmosphere in spacecraft and space stations, but will allow it in space suit (in a desperate attempt to lower the suit pressure to the point where the astronaut can move their limbs instead of being trapped into a posture like a star-fish).

So NASA astronauts do a lot of prebreathing. This flushes nitrogen out of the blood stream. NASA uses Terra-normal pressure (14.7 psi) inside the Space Shuttle, but only 0.29 pressure (4.5 psi) with pure oxygen in the space suits. The prebreathing is officially called the In Suit Light Exercise (ISLE) Prebreath Protocol, and unofficially called the "Slow Motion Hokey Pokey".

The astronaut(s) enter the airlock, and the airlock pressure is reduced to 10.2 psi. They breath pure oxygen through masks for 60 minutes (because the air in the airlock contains nitrogen). They then put on their space suits and do an EMU purge (i.e., flush out all the airlock-air that got into the suit while they were putting it on, to get rid of stray nitrogen). The air inside their suits is now also pure oxygen. The airlock pressure is then brought back up to the normal 14.7 psi. They then do 100 minutes of in-suit prebreath. Of those 100 minutes, 50 of them are light-exercise minutes and 50 of them are resting minutes. "Light exercise" is defined as: flex your knees for 4 minutes, rest 1 minute, repeat until 50 minutes has passed. Thus "Slow Motion Hokey Pokey". Now they are ready to open the airlock and step into space.

The innovation was the 50 minutes of exercise. Without it, the entire protocol takes twelve hours instead of one hour and fifty minutes.

If the habitat module's pressure was 12 psi an astronaut could use an 8 psi space suit with no prebreathing required (a pity such suits are currently beyond the state of the art), and for a 4.5 psi suit the prebreathing time would be cut in half.

In case of emergency, when there is no time for prebreathing, NASA helpfully directs the astronauts to gulp aspirin, so they can work in spite of the agonizing pain

Please note that most of the problem is due to the fact that soft space suits have a lower atmospheric pressure than the habitat module. So this can be avoided by using a hard space suit or space pod.

Ventilation

On a related note, forced ventilation in the spacecraft's lifesystem is not optional. In free fall, the warm exhaled carbon dioxide will not rise away from your face. It will just collect in a cloud around your head until you pass out or suffocate. In Arthur C. Clarke's ISLANDS IN THE SKY the apprentices play a practical joke on the main character using this fact and a common match. In the image above the blue dome shaped flame is an actual candle burning in free fall. All of the atmospheric controls will be on the life support deck.

And yes, on Skylab, the area around the the air vent got pretty disgusting quite quickly, as all the floating food particles and assorted dirt from the entire space station got sucked in. In some SF novels the slang name for the air vents is "The Lost and Found Department."

There were also, I'd discovered, some interesting tricks and practical jokes that could be played in space. One of the best involved nothing more complicated than an ordinary match. We were in the classroom one afternoon when Norman suddenly turned to me and said: 'Do you know how to test the air to see if it's breathable?'

'If it wasn't, I suppose you'd soon know,' I replied.

'Not at all — you might be knocked out too quickly to do anything about it. But there's a simple test which has been used on Earth for ages, in mines and caves. You just carry a flame ahead of you, and if it goes out — well, you go out too, as quickly as you can!' He fumbled in his pocket and extracted a box of matches. I was mildly surprised to see something so old-fashioned aboard the Station.

'In here, of course,' Norman continued, 'a flame will burn properly. But if the air were bad it would go out at once.' He absent-mindedly stroked the match on the box and it burst into light. A flame formed around the head — and I leaned forward to look at it closely. It was a very odd flame, not long and pointed but quite spherical. Even as I watched it dwindled and died.

It's funny how the mind works, for up to that moment I'd been breathing perfectly comfortably, yet now I seemed to be suffocating. I looked at Norman, and said nervously: 'Try it again — there must be something wrong with the match.'

Obediently he struck another, which expired as quickly as the first.

'Let's get out of here,' I gasped. 'The air-purifier must have packed up.' Then I saw that the others were grinning at me.

'Don't panic, Roy,' said Tim. 'There's a simple answer.' He grabbed the match-box from Norman. 'The air's perfectly O.K. but if you think about it, you'll see that it's impossible for a flame to burn out here. Since there's no gravity and everything stays put, the smoke doesn't rise and the flame just chokes itself. The only way it will keep burning is if you do this.'

He struck another match, but instead of holding it still, kept it moving slowly through the air. It left a trail of smoke behind it, and kept on burning until only the stump was left.

'It was entering fresh air all the time, so it didn't choke itself with burnt gases. And if you think this is just an amusing trick of no practical importance, you're wrong. It means we've got to keep the air in the Station on the move, otherwise we'd soon go the same way as that flame. Norman, will you switch on the ventilators again, now that you've had your little joke?'

From Islands in the Sky by Sir Arthur C. Clarke (1954)

The Avenger had long since disappeared and Tom was left alone in space in the tiny jet boat. To conserve his oxygen supply, the curly-haired cadet had set the controls of his boat on a steady orbit around one of the larger asteroids and lay down quietly on the deck. One of the first lessons he had learned at Space Academy was, during an emergency in space when oxygen was low, to lie down and breath as slowly as possible. And, if possible, to go to sleep. Sleep, under such conditions, served two purposes. While relaxed in sleep, the body used less oxygen and should help fail to arrive, the victim would slip into a suffocating unconsciousness, not knowing if and when death took the place of life.

From On the Trail of Space Pirates by Carey Rockwell (1953) a Tom Corbett Space Cadet book

Odors

Unpleasant odors in the air is a problem, but there is not much one can do about it. After all, you can't just open up a window to let in some fresh air, not in the vacuum of space. NASA carefully screens all materials, sealants, foods, and everything else to ensure that they do not emit noticeable odor in the pressurized habitat sections of spacecraft and space stations. Such odors can quickly become overpowering in such tight quarters.

There's a fortune awaiting the man who invents a really good deodorizer for a spaceship. That's the one thing you can't fail to notice.

Oh, they try, I grant them that. The air goes through precipitators each time it is cycled; it is washed, it is perfumed, a precise fraction of ozone is added, and the new oxygen that is put in after the carbon dioxide is distilled out is as pure as a baby's mind; it has to be, for it is newly released as a by-product of the photosynthesis of living plants. That air is so pure that it really ought to be voted a medal by the Society for the Suppression of Evil Thoughts.

Besides that, a simply amazing amount of the crew's time is put into cleaning, polishing, washing, sterilizing - oh, they try!

But nevertheless, even a new, extra-fare luxury liner like the Tricorn simply reeks of human sweat and ancient sin, with undefinable overtones of organic decay and unfortunate accidents and matters best forgotten. Once I was with Daddy when a Martian tomb was being unsealed - and I found out why xenoarchaeologists always have gas masks handy. But a spaceship smells even worse than that tomb.

It does no good to complain to the purser. He'll listen with professional sympathy and send a crewman around to spray your stateroom with something which (I suspect) merely deadens your nose for a while. But his sympathy is not real, because the poor man simply cannot smell anything wrong himself. He has lived in ships for years; it is literally impossible for him to smell the unmistakable reek of a ship that has been lived in - and, besides, he knows that the air is pure; the ship's instruments show it. None of the professional spacers can smell it.

But the purser and all of them are quite used to having passengers complain about the "unbearable stench" - so they pretend sympathy and go through the motions of correcting the matter.

Not that I complained. I was looking forward to having this ship eating out of my hand, and you don't accomplish that sort of coup by becoming known first thing as a complainer. But other first-timers did, and I certainly understood why - in fact I began to have a glimmer of a doubt about my ambitions to become skipper of an explorer ship.

But - Well, in about two days it seemed to me that they had managed to clean up the ship quite a bit, and shortly thereafter I stopped thinking about it. I began to understand why the ship's crew can't smell the things the passengers complain about. Their nervous systems simply cancel out the old familiar stinks - like a cybernetic skywatch canceling out and ignoring any object whose predicted orbit has previously been programmed into the machine.

But the odor is still there. I suspect that it sinks right into polished metal and can never be removed, short of scrapping the ship and melting it down. Thank goodness the human nervous system is endlessly adaptable.

From Podkayne of Mars by Robert Heinlein

(ed note: US captain John Fitzthomas and Chinese captain June Tran are talking)

(June Tran said) "Take all the politicians, and draft them into the space navies. Make them spend a year cooped up on a spaceship. Don't let them out. Don't even let them go to astrogation and look through the telescope at the stars. Just them and the metal on all sides of them. Food that tastes like plastic. Air that smells like sweat and farts."

"I know, I know. I'm sorry. It's just, well, we don't have the last problem anymore."


"No. I want to see the lake. I have heard all their stories anyway. And you haven't told me the secret of how you keep your spaceship from stinking."

"Oh, it's not a secret. We have a Gadget. It's standard issue."

"A Gadget?"

"Yes. Tell me you've never heard of a Gadget."

"I'm afraid I have not."

"It's wonderful. It's a little machine you place right at the out vent of your gas exchanger, right where the oxygenated air gets pumped back into the ventilation system. It has some kind of filter that neutralizes all the smells that usually build up; it learns what your ship smells like so it can clean the air more efficiently. Then it perfumes the outgoing air with whatever you want."

"You're kidding."

"I'm not kidding at all. It's a godsend. The guy who invented it was this California nisei named Takumi Maeda. He made a fortune selling them. He has a company now that makes all kinds of stuff."

"I have never heard of this man or his miraculous invention."

"You mean to tell me you've never heard of International Gadgets?"

"We don't see many American products in Oz."

"Apparently not, because you don't have a Gadget."

"What does yours smell like?"

"Cinnamon rolls now. The crew votes every week on a new one so we don't get tired of any one smell. Last week it was baby powder."

Tran laughed and clapped her hands together. "I shall inform my superiors of this miracle invention. Perhaps an exception to the embargo can be found."

"Maybe they'd be more willing to listen if you had a demo model."

"Where would I get one of those?"

"I have two spares. I could loan you one in the name of international peace and understanding."

"That would be wonderful, John. Assuming, of course, it actually works as advertised."

"It will. It comes with adapters for different vents, too, so it should fit yours fine even if you don't use the same size we do."

From The Last Great War by Matthew Lineberger (not yet published)

Removing Carbon Dioxide

It is not enough to supply oxygen to breath, you also have to remove the carbon dixoide. Bad things happen if the CO2 levels rise too high.

  • 0.04 percent - Typical level in Terra's atmmosphere
  • At 1 percent - drowsiness
  • At 3 percent - impaired hearing, increased heart rate and blood pressure, stupor
  • At 5 percent - shortness of breath, headache, dizziness, confusion
  • At 8 percent - unconsciousness, muscle tremors, sweating
  • Above 8 percent - death

NASA uses Carbon Dioxide Scrubbers. In the Apollo program spacecraft, NASA used lithium hydroxide based scrubbers, which fill up and have to be replaced.

You may remember all the excitement during the Apollo 13 disaster, when NASA learned the life-threatening dangers of non-standardization. The crew had to use the Command Modules' scrubber cartridges to replace the ones in the Lunar module. Unfortunately, due to lack of standardization, the CM cartridges would not fit into the LM life support system (CM's were square, LM were cylindrical). They had to rig an adaptor out of duct tape and whatever else was on-board.

In the Space Shuttle, NASA moved to a Regenerative carbon dioxide removal system. Metal-oxide scrubbers remove the CO2 as before. But when they get full, instead of being replaced, they can have the CO2 flushed out by running hot air through it for ten hours. Then they can be reused.

..."That puts me in mind of something that happened to me when I was 'farmer' in the old Percival Lowell -- the one before the present one," Yancey went on. "We had touched at Venus South Pole and had managed somehow to get a virus infection, a sort of rust, into the 'farm' -- don't look so superior, Mr. Jensen; someday you'll come a cropper with a planet that is new to you!"

"Me, sir? I wasn't looking superior."

"No? Smiling at the pansies, no doubt?"

"Yes, sir."

"Hmmph! As I was saying, we got this rust infection about ten days out. I didn't have any more farm than an Eskimo. I cleaned the place out, sterilized, and reseeded. Same story. The infection was all through the ship and I couldn't chase it down. We finished that trip on preserved foods and short rations and I wasn't allowed to eat at the table the rest of the trip."

"Captain?"

"Yes, Dodson?"

"What did you do about air-conditioning?"

"Well. Mister, what would you have done?"

Matt studied it. "Well, sir, I would have jury-rigged something to take the Cee-Oh-Two out of the air."

"Precisely. I exhausted the air from an empty compartment, suited up, and drilled a couple of holes to the outside. Then I did a piping job to carry foul air out of the dark side of the ship in a fractional still arrangement -- freeze out the water first, then freeze out the carbon dioxide. Pesky thing was always freezing up solid and forcing me to tinker with it. But it worked well enough to get us home."

From SPACE CADET by Robert Heinlein. 1948.

"Check the oxygen supplies first," the voice of Thorndyke, the head engineer, suggested.

Bart and Dan went off to do that, and Jim followed behind them. But from their faces, he could tell that their hopes weren't too high. Obviously, most of the oxygen had been put into the new extension, since there was more room there for the big containers of liquid oxygen. They had been in the shadow, below the main part of the hull, where they could stay liquid; but the heat of the fire had bent and twisted them, and some had even exploded violently.

"Takes three pounds of oxygen a day for a man," Dan said. "You'll find the amount on the outside of the tanks. Gauge will tell you what per cent has been used." He went back into the rear extension, leaving Bart and Jim to count the amount in the original hut. It was a lot less than they would have liked.


"According to those figures, we've got just enough air left for all the men here for about thirty hours! And we don't have chemicals to soak up the carbon dioxide they breathe out for even that long."


"The big problem's in getting rid of the carbon dioxide," Thorndyke said flatly. "If we could handle that, we might just barely survive until the storm had let up enough for another ship to try.


In a vague way, Jim still felt responsible for the trouble. He should have checked on his assistant. He'd been beating his head, trying to remember what he'd learned in high school about the behavior of the gas. His father had always maintained that a man could accomplish almost anything by reducing things down to the basic characteristics, and then finding out what was done in other fields.

"It's a heavy gas," someone said suddenly. "If we all climb up to the top where the lighter oxygen is . . ."

He realized his mistake before the others swung on him. Thorndyke chuckled grimly. "It's the same here as anything else—neither fight nor heavy," he pointed out. "But all the same, you're moving in the right direction. What are the basic characteristics of carbon dioxide?"

The young man who'd studied chemistry piped up again. "It's a heavy gas, composed of one atom of carbon and two of oxygen. Animals breathe it out, and plants breathe it in, releasing the oxygen again. It freezes directly to a solid, without any real liquid state, and is then known as dry ice. It evaporates . . ."

"It freezes at a higher temperature than air!" Jim shouted. "That's how they make dry ice—they lower the temperature enough for carbon dioxide to freeze, but the rest of the atmosphere stays a gas. What about the cold side—does it get cold enough to freeze it out?"

"How cold?" Thorndyke asked. "Never mind." He reached over for a copy of the Handbook of Chemistry and Physics and ran through it. "If we didn't pass it through too fast, our air would probably lose most of the gas from the cold. Dan, any way to get a gastight pan . . ."

"You've got the pipes under the solar mirror trough," Dan pointed out. "They're all coupled up. We could blow it through there slowly enough—trial and error should tell us how slowly."

From Step to the Stars by Lester Del Rey. 1954

Meteor Punctures

Meteors are probably nothing to worry about. On average a spacecraft will have to wait for a couple of million years to be hit by a meteor larger than a grain of sand. But if you insist, there are a couple of precautions one can take.

First one can sheath the ship in a thin shell with a few inches of separation from the hull. This "meteor bumper" (aka "Whipple shield") will vaporize the smaller guys.

For larger ones, use radar. It is surprisingly simple. For complicated reasons that I'm sure you can figure out for yourself, a meteor on a collision course will maintain a constant bearing (it's a geometric matter of similar triangles). So if the radar sees an object whose bearing doesn't change, but whose range is decreasing, it knows that You Have A Problem. (This happens on Earth as well. If you are racing a freight train to cross an intersection, and the image of the front of the train stays on one spot on your windshield, you know that you and the engine will reach the intersection simultaneously. This example was from Heinlein's ROCKET SHIP GALILEO.)

(Ken Burnside used this concept in his starship combat game Attack Vector: Tactical. From the point-of-view of the target, the incoming missile will hit if it stays on one bearing and does not move laterally. So a game aid called a ShellStar is used to detect the presence of lateral motion.)

The solution is simple as well, burn the engine a second or two in any direction (That was from Heinlein's SPACE CADET). One can make an hard-wired link between the radar and the engines, but it might be a good idea to have it sound an alarm first. This will give the crew a second to grab a hand-hold. You did install hand-holds on all the walls, didn't you? And require the crew to strap themselves into their bunks while sleeping.

The moon, now visibly larger and almost painfully beautiful, hung in the same position in the sky, such that he had to let his gaze drop as he lay in the chair in order to return its stare. This bothered him for a moment -- how were they ever to reach the moon if the moon did not draw toward the point where they were aiming?

It would not have bothered Morrie, trained as he was in a pilot's knowledge of collision bearings, interception courses, and the like. But, since it appeared to run contrary to common sense, Art worried about it until he managed to visualize the situation somewhat thus: if a car is speeding for a railroad crossing and a train is approaching from the left, so that their combined speeds will bring about a wreck, then the bearing of the locomotive from the automobile will not change, right up to the moment of the collision.

It was a simple matter of similar triangles, easy to see with a diagram but hard to keep straight in the head. The moon was speeding to their meeting place at about 2000 miles an hour, yet she would never change direction; she would simply grow and grow and grow until she filled the whole sky.

From ROCKET SHIP GALILEO by Robert Heinlein. 1947.

To guard against larger stuff Captain Yancey set up a meteor-watch much tighter than is usual in most parts of space. Eight radars scanned all space through a global 360°. The only condition necessary for collision is that the other object hold a steady bearing-no fancy calculation is involved. The only action necessary then to avoid collision is to change your own speed, any direction, any amount. This is perhaps the only case where theory of piloting is simple.

Commander Miller put the cadets and the sublieutenants on a continuous heel-and-toe watch, scanning the meteor-guard 'scopes. Even if the human being failed to note a steady bearing the radars would "see" it, for they were so rigged that, if a "blip" burned in at one spot on the screen, thereby showing a steady bearing, an alarm would sound- and the watch officer would cut in the jet, fast!...

From SPACE CADET by Robert Heinlein. 1948.

Hull Patching

What if the meteor hits the ship and punctures the hull? An instrument called a Manometer will register a sudden loss of pressure and trigger an alarm. Life support will start high-pressure flood of oxygen, and release some bubbles. The bubbles will rush to the breach, pointing them out to the crew. The crew will grab an emergency hull patch (thoughtfully affixed near all external hull walls) and seal the breach. A more advanced alternative to bubbles are "plug-ups" or "tag-alongs". These are plastic bubbles full of helium and liquid sealing plastic. The helium is enough to give them neutral buoyancy, so they have no strong tendency to rise or sink. They fly to the breach, pop, and plug it with quick setting goo. Much to the relief of the crew caught in the same room with the breach when the automatic bulkheads slammed shut.

Now you have some breathing space to break out the arc welder and apply a proper patch.

The emergency hull patches are metal discs. They look like saucepan covers with a rubber flange around the edge. They will handle a breach up to six inches in diameter. Never slap them over the breach, place it on the hull next to the breach and slide it over. Once over the breach, air pressure will hold it in place until you can make more permanent repairs.

"Where're the plug-ups?" the Commander demands. "Damn it, where the hell are the plug-ups?"

"Oh." The man doing the relay talking hits a switch. Little gas-filled plastic balls swarm into the compartment. They range from golf-ball to tennis-ball size.

"Enough. Enough," Nicastro growls. "We've got to be able to see."

A new man, I decide. He's heard about the Commander. He's too anxious to look good. He's concentrating too much. Doing his job one part at a time, with such thoroughness that he muffs the whole.

The plug-ups will drift aimlessly throughout the patrol, and will soon fade into the background environment. No one will think about them unless the hull is breached. Then our lives could depend on them. They'll rush to the hole, carried by the escaping atmosphere. If the breach is small, they'll break trying to get through. A quick-setting, oxygen-sensitive goo coats their insides.

The cat scrambles after the nearest ball. He bats it around. It survives his attentions. He pretends a towering indifference. He's a master of that talent of the feline breed, of adopting a regal dignity in the face of failure, just in case somebody is watching.

Breaches too big for the plug-ups probably wouldn't matter. We would be dead before we noticed them.

From Passage at Arms by Glen Cook (1985)

(ed note: a reporter is touring some Lunar tunnels being drilled to expand the colony)

"Yes and no. The airlocks would limit an accident all right, if there was one—which there won't be—this place is safe. Primarily they let us work on a section of the tunnel at no pressure without disturbing the rest of it. But they are more than that; each one is a temporary expansion joint. You can tie a compact structure together and let it ride out a quake, but a thing as long as this tunnel has to give, or it will spring a leak. A flexible seal is hard to accomplish in the Moon."

"What's wrong with rubber?" I demanded. I was feeling jumpy enough to be argumentative. "I've got a ground-car back home with two hundred thousand miles on it, yet I've never touched the tires since they were sealed up in Detroit."

Knowles sighed. "I should have brought one of the engineers along, Jack. The volatiles that keep rubbers soft tend to boil away in vacuum and the stuff gets stiff. Same for the flexible plastics. When you expose them to low temperature as well they get brittle as eggshells."


There were perhaps a dozen bladder-like objects in the tunnel, the size and shape of toy balloons. They seemed to displace exactly their own weight of air; they floated without displaying much tendency to rise or settle. Konski batted one out of his way and answered me before I could ask. "This piece of tunnel was pressurized today," he told me. "These tag-alongs search out stray leaks. They're sticky inside. They get sucked up against a leak, break, and the goo gets sucked in, freezes and seals the leak."

"Is that a permanent repair?" I wanted to know.

"Are you kidding? It just shows the follow-up man where to weld."

"Show him a flexible joint," Knowles directed.

"Coming up." We paused half-way down the tunnel and Konski pointed to a ring segment that ran completely around the tubular tunnel. "We put in a flex joint every hundred feet. It's glass cloth, gasketed onto the two steel sections it joins. Gives the tunnel a certain amount of springiness."

"Glass cloth? To make an airtight seal?" I objected.

"The cloth doesn't seal; it's for strength. You got ten layers of cloth, with a silicone grease spread between the layers. It gradually goes bad, from the outside in, but it'll hold five years or more before you have to put on another coat."

(ed note: then the accident happens)


"Looks tight, but I hear—Oh, oh! Sister!" His beam was focused on a part of the flexible joint, near the floor.

The "tag-along" balloons were gathering at this spot. Three were already there; others were drifting in slowly. As we watched, one of them burst and collapsed in a sticky mass that marked the leak.

The hole sucked up the burst balloon and began to hiss. Another rolled onto the spot, joggled about a bit, then it, too, burst. It took a little longer this time for the leak to absorb and swallow the gummy mass.

Konski passed me the light. "Keep pumping it, kid." He shrugged his right arm out of the suit and placed his bare hand over the spot where, at that moment, a third bladder burst.

"How about it, Fats?" Mr. Knowles demanded.

"Couldn't say. Feels like a hole as big as my thumb. Sucks like the devil."

"You got the leak checked?"

"I think so. Go back and check the gage. Jack, give him the light."

Knowles trotted back to the airlock. Presently he sang out, "Pressure steady!"

"Can you read the vernier?" Konski called to him.

"Sure. Steady by the vernier."

"How much we lose?"

"Not more than a pound or two. What was the pressure before?"

"Earth-normal."

"Lost a pound four tenths, then."

"Not bad. Keep on going, Mr. Knowles. There's a tool kit just beyond the lock in the next section. Bring me back a number three patch, or bigger."

"Right." We heard the door open and clang shut, and we were again in total darkness. I must have made some sound for Konski told me to keep my chin up.

Presently we heard the door, and the blessed light shone out again. "Got it?" said Konski.

"No, Fatso. No..." Knowles' voice was shaking. "There's no air on the other side. The other door wouldn't open."

"Jammed, maybe?"

"No, I checked the manometer. There's no pressure in the next section."

Konski whistled again. "Looks like we'll wait till they come for us. In that case — Keep the light on me, Mr. Knowles. Jack, help me out of this suit."

"What are you planning to do?"

"If I can't get a patch, I got to make one, Mr. Knowles. This suit is the only thing around." I started to help him—a clumsy job since he had to keep his hand on the leak.

"You can stuff my shirt in the hole," Knowles suggested.

"I'd as soon bail water with a fork. It's got to be the suit; there's nothing else around that will hold the pressure." When he was free of the suit, he had me smooth out a portion of the back, then, as he snatched his hand away, I slapped the suit down over the leak. Konski promptly sat on it. "There," he said happily, "we've got it corked. Nothing to do but wait."

I started to ask him why he hadn't just sat down on the leak while wearing the suit; then I realized that the seat of the suit was corrugated with insulation—he needed a smooth piece to seal on to the sticky stuff left by the balloons.

"Let me see your hand," Knowles demanded.

"It's nothing much." But Knowles examined it anyway. I looked at it and got a little sick. He had a mark like a stigma on the palm, a bloody, oozing wound. Knowles made a compress of his handkerchief and then used mine to tie it in place.

From Gentlemen, Be Seated! by Robert Heinlein (1948)

Assuming Terra-normal pressure and density inside, and zero pressure outside, the effective speed of the air whistling out the breach works out to a smidgen under 400 m/sec. Veteran rocketeers, vacationing on Terra, tend to have a momentary panic if they feel the wind. Their instincts tell them there is a hull breach.

∂m/∂t = A * sqrt( 2 * P * rho )

where

  • ∂m/∂t = the rate (mass per unit time) at which air leaks into vacuum
  • A = Area of the hole it's leaking through
  • P = Pressure inside the room far from the hole
  • rho = density inside the room far from the hole

More simply, assuming Terra-normal pressure and density,

whooshTime = ( gaspFactor * vol) / holeArea

where

  • gaspFactor = 1.4 for 80% pressure, 4.3 for 50% pressure, 29 for 1% pressure.
  • whooshTime = time for cabin pressure to drop to specified fraction of
  • initial value (seconds)
  • vol = volume of air in the cabin (yards3)
  • holeArea = area of the breach (inch2)

(equation from GURPS:Lensman)

So if a posh passenger cabin of 20 cubic yards has a one square inch hole blown in the bulkhead by a wayward meteor, the inhabitants have an entire 86 seconds (about a minute and a half) before the atmospheric pressure drops to one-half.

Somebody in a space suit doesn't have that kind of time. The suit has a volume of approximately 0.03 cubic yards. A hole a quarter inch in diameter has a hole area of 0.05 square inches. As long as the suit's air tanks can keep up the loss the pressure won't drop. But once the tanks are empty, the pressure will drop by one-half in a mere 2.4 seconds.

Does this mean that crewpeople in a combat spacecraft will do their fighting in space suits? Probably not, for the same reason that crewpeople in combat submarines do not do their fighting while wearing scuba gear. The gear is bulky, confining, and tiring to wear. They will not wear it even though in both cases the vessel is surrounded by stuff you cannot breath. They may, however, wear partial-pressure suits. Those suits will only protect you for ten minutes or so, but in exchange you won't be hampered like you were wearing three sets of snow-suits simultaneously.

Instead, the ship's pressurized inhabitable section will be divided into individual sections by bulkheads, and the connecting airtight hatches will be shut. The air pressure might be lowered a bit.

Brian Davis

This came up in a different newsgroup, and upon trying to answer it I blew it badly. I’m not sure the original group really cares, but folks here might, and it’s kind of interesting to me, so…

Let’s say you have a person (named, let’s say, “Callie”) standing in the middle of a large airlock (10 [m] long by 3[m] by 3[m]). The bad girl opens the large doors at the end, “blowing the lock” (it starts at 1 [Atm]). What happens to the helpless heroine? I understand decompression, but I’m trying to figure out how fast (if at all) they “exit” the airlock. For a first cut, I assumed the doors instantly crack open 10 [cm] along their entire 3 [m] length, forming a “breach” with an area of 0.3 [m2] through which the air starts rushing at roughly Mach 1 (I know it would be less, but ballpark). Back by Callie, the cross-sectional area is about 9 [m2], so conservation of mass (assuming uniform density) says the airspeed by her is a gusty 11.1 [m/s]… which is pretty much trivial. I assumed she is accelerated “breachward” by the stagnation pressure of this flow against the front of her body (frontal surface area 0.36 [m2, mass of 45 [kg]), but the result is a really trivial acceleration. Running it through Excel (to keep track of the rapid density/pressure drop, which reduces the stagnation pressure all the more), I get her hitting the breach after a little over 8.5 [sec], and the leisurely pace of about 0.67 [m/s] (a slow walk). She really only accelerates for the first couple seconds, after that the lock is at such a low pressure that the remaining “wind” just doesn’t have enough force to do anything.

OK, so what did I screw up? I realize approximating the exit velocity as 333 [m/s] isn’t good, and I’m ignoring the question of adiabatic vs. nonadiabatic effects, etc. I do take into account the increased airspeed as she gets very close to the breach (closer than 2 [m] or so). But anything major? Or does Callie really fully decompress in the airlock, and gently drift out about 10 seconds later? One interesting artifact of my calculation is that Callie takes a sharp jump up in velocity during the brief time she “wedges” in the breach, but I’m not as worried about that because in the real situation, the doors would have been fully opened by then.

PS- I’d love to take the rate of the doors opening (i.e., breach area increasing) into account, but it makes things more difficult, and in particular makes the assumption of sonicly-limited flow questionable (if the “breach” is one entire side of your airlock, I think I have to worry about the force required to accelerate the mass of air in addition to everything else, yes?).


John Park

I haven't verified your numbers, but for a quick sanity check, there's about 100 kg of air in the lock, but only half of that is behind her—her own body weight—and most of that will escape past her. If you really want the damsel to experience dramatic accelerations, I think you should start her closer to the opening, or have the inner door open, or maybe use a longer, thinner lock that she almost blocks with her body.


Tim Little

(Brian Davis: She really only accelerates for the first couple seconds, after that the lock is at such a low pressure that the remaining 'wind' just doesn't have enough force to do anything.)

Yes, that's about right, if the door opens outward and sticks at a 10 cm gap. Though actually I'd be very surprised to see an airlock with a door that opened outward at all.

If it did open outward, and was free to swing open wider, consider that it has 100 kPa pressure acting on the inner surface. It will accelerate open very rapidly indeed — probably on the order of tens of milliseconds.

Though even in that situation, I'd guess Callie would exit the airlock with only on the order of 1-3 m/s velocity, long after the air is gone.

(Brian Davis: Or does Callie really fully decompress in the airlock, and gently drift out about 10 seconds later?)

Yes.

(Brian Davis: if the breach is one entire side of your airlock, I think I have to worry about the force required to accelerate the mass of air in addition to everything else, yes?)

Sort of. The rarefaction front will propagate inward at the speed of sound, with the air accelerated nearly instantaneously as the front passes. The temperature behind the front will be some fraction of the starting temperature — I'd guess about 4/5 from one thermal degree of freedom out of five being converted to kinetic energy.

The relation for adiabatic expansion then gives a pressure behind the front of about 46% of the initial pressure, and an exit speed of about 250 m/s.

That will exert a lot of force on Callie, but only for about 20-30 ms.


Dr J. R. Stockton

(Brian Davis: Let’s say you have a person (named, let’s say, “Callie”) standing in the middle of a large airlock (10 [m] long by 3[m] by 3[m]). The bad girl opens the large doors at the end, “blowing the lock” (it starts at 1 [Atm]). What happens to the helpless heroine?)

At worst, approximately, and assuming a heroine of only moderate size (i.e., not a plug) : since the molecular speed is about the speed of sound, the energy can only accelerate the gas to about the speed of sound, 330 m/s. The heroine, being around a thousand times more dense than air, will be accelerated to about a thousandth of that, around a foot per second.

A worst case approximation is that a transition between 105 Pa and 0 Pa propagates past her at 330 m/s. So, per square metre, she gets 105 N for a duration of T/330 s, where T is her thickness in metres. Her mean density will be, of course, 1000 in SI units, so per square metre her mass is 1000×T; so her change in speed will be 105 × T/330 / 1000×T, which is about 0.3 m/s.

One cannot recommend, for the usual purposes, a heroine who obstructs a substantial proportion of nine square metres.


Tim Little

(Dr J R Stockton: A worst case approximation is that a transition between 105 Pa and 0 Pa propagates past her at 330 m/s. So, per square metre, she gets 105 N for a duration of T/330 s, where T is her thickness in metres.)

The duration is much longer than that, since she is still in the path of the air escaping from further back in the airlock. Even though the static pressure is at 0 Pa, it still has significant density.

In particular, if c is the usual speed of sound, and v is the speed to which the rarefaction wave accelerates the air, simple conservation of mass puts the density ratio at c/(c+v).

So the air rushing past her from further in the airlock will exert pressure as it escapes past her. So for a long airlock, her velocity would asymptotically approach the free outflow speed.

This is a fairly short airlock, but certainly longer than her average thickness.


John Schilling

(Dr J R Stockton: At worst, approximately, and assuming a heroine of only moderate size (i.e. not a plug) : since the molecular speed is about the speed of sound, the energy can only accelerate the gas to about the speed of sound, 330 m/s. The heroine, being around a thousand times more dense than air, will be accelerated to about a thousandth of that, around a foot per second.

A worst case approximation is that a transition between 105 Pa and 0 Pa propagates past her at 330 m/s. So, per square metre, she gets 105 N for a duration of T/330 s, where T is her thickness in metres. Her mean density will be, of course, 1000 in SI units, so per square metre her mass is 1000×T; so her change in speed will be 105 × T/330 / 1000×T, which is about 0.3 m/s.)

Ah, so if I hang a sheet of tissue paper just inside the airlock of an O'Neill habitat, and open the door, it won't go anywhere, right? Because all it will experience is an infinitesimal moment of acceleration as the transition between atmosphere and vacuum propagates past its negligible thickness?

I'm thinking that's not right. I'm also thinking that a propagating transition between atmosphere and vacuum would represent a violation of the law of conservation of mass.

What actually propagates, is a transition between air at 105 Pa, and air at 5.28×104 Pa moving outwards at 310.42 m/s. And that transonic wind condition, remains even after the transition has passed — for as long as it takes for the transition wave to reach the farthest wall of the chamber behind our heroine, and as long beyond that as it takes for the wind to actually empty the chamber.

If the geometry is cylindrical, I get for a standard heroine in a standard atmosphere, a net velocity of 1.8 m/s per meter length of air-filled volume behind her. That's in the low-velocity limit; as she herself approaches transonic velocity downstream, the force will decrease and her own velocity will asymptotically approach 310.42 m/s.

If the geometry is not cylindrical, it gets rather more complicated of course.


Erik Max Francis

(Brian Davis: OK, so what did I screw up?)

Nothing, I'd say. The ability for explosive decompression to push people around is usually exaggerated. Your results sound qualitatively like I'd expect — it'd budge her a little at first but very rapidly the ambient air pressure would drop to the point that it wouldn't have much of an effect.


Russell Wallace

That's interesting, because it appears to conflict with the usual description of explosive decompression on aircraft: even a fairly small hole in e.g., an airliner at altitude, will cause everything that isn't nailed down — including people who aren't strapped into their seats — to be quickly sucked out the hole. Is that description simply inaccurate, or is there a difference in the cases that I'm missing?


Wayne Throop

It's inaccurate. I seem to recall there was a Mythbusters that concluded "busted".


Tim Little

(Russell Wallace: an airliner at altitude, will cause everything that isn't nailed down — including people who aren't strapped into their seats — to be quickly sucked out the hole. Is that description simply inaccurate, or is there a difference in the cases that I'm missing?)

It is simply inaccurate. Yes, decompression is dangerous, and if a significant hole opens up the winds can be extreme. But they're not caused by the decompression!

It should be noted that an airliner at altitude is usually moving at a significant fraction of the speed of sound through the air. The air doesn't just simply leave as it would in a vacuum, or if it were a zeppelin cabin.

From the point of view of the aircraft, the air outside has kinetic energy greater than any hurricane. If a large hole opens up, part of that can get in.


Erik Max Francis

It depends on how much air is in the vessel, how big the hole is, and how close the victim is to the breach. Sure, there are some cases where the victim will likely be forced out of the breach. But probably not in the case Brian was talking about. Not that really helps her chances, since she's exposed to vacuum with no way to get back in.


Michael Ash

The image of everything that's not nailed down flying out the door may be inaccurate, but the earlier estimate of 0.3m/s would appear to be inaccurate as well. Perhaps the most famous explosive decompression incident is Aloha Airlines 243 which suddenly lost a large section of skin but managed to land safely. One flight attendant was thrown to the floor and another one was thrown out of the plane altogether, never to be seen again. A 737 isn't particularly large but it would require substantially more imparted velocity than that to throw somebody out. A spacecraft pressurized to 1 atmosphere should be a bit worse as well, since the accident in question occurred at 24,000ft where the outside air pressure is still about 0.4 atmospheres.

It should be noted that a small hole doesn't do this, because a small hole doesn't result in explosive decompression in the first place. A small hole will leak, not cause a bang, and there would just be some wind. Thus the fears of instant death due to a gunfight piercing the hull are completely overblown, and I believe this is what Mythbusters investigated. But this is an entirely different scenario from opening a large airlock door or the case of the poor Aloha Airlines flight attendant.


Wayne Throop

Sure, but that's what being exposed to 300+mph winds will get you. Just the decompression, not so much. It's the fact that so much of the hull was peeled away.

The Mythbusters bit (iirc) was concerned with two aspects of a fairly small hole. First, will it suck everything inside towards it, and second, will it rip the hull open and expose the interior to the airstream (that is, will any small break in the skin necessarily spread very far). And they concluded, no and no. Of course, they were talking about a bullethole (again iirc). But I doubt things would be much different for anybody at a reasonable distance from, say, a hatch-sized hole. An upper-half-of-the-hull-peels-away-in-a-section-tens-of-feet-long sized hole is another matter entirely, and I doubt anybody will notice the decompression, given the brisk breeze outside.


Robert Martinu

(Wayne Throop: And they concluded, no and no. Of course, they were talking about a bullethole (again iirc). But I doubt things would be much different for anybody at a reasonable distance from, say, a hatch-sized hole.)

Later the episode they tested what a moderate amount of explosives would do to the pressurized hull. The result was iirc a seat cusion sucked out, but the dummy still in its seat. Again its not the decompression you have to fear.

From Explosive decompression - how fast? thread in rec.arts.sf.science 4/26/2008

It was just after reveille, "A" deck time, and I was standing by my bunk, making it up. I had my Scout uniform in my hands and was about to fold it up and put it under my pillow. I still didn't wear it. None of the others had uniforms to wear to Scout meetings so I didn't wear mine. But I still kept it tucked away in my bunk.

Suddenly I heard the goldarnest noise I ever heard in my life. It sounded like a rifle going off right by my ear, it sounded like a steel door being slammed, and it sounded like a giant tearing yards and yards of cloth, all at once.

Then I couldn't hear anything but a ringing in my ears and I was dazed. I shook my head and looked down and I was staring at a raw hole in the ship, almost between my feet and nearly as big as my fist. There was scorched insulation around it and in the middle of the hole I could see blackness—then a star whipped past and I realized that I was staring right out into space.

There was a hissing noise.

I don't remember thinking at all. I just wadded up my uniform, squatted down, and stuffed it in the hole. For a moment it seemed as if the suction would pull it on through the hole, then it jammed and stuck and didn't go any further. But we were still losing air. I think that was the point at which I first realized that we were losing air and that we might be suffocated in vacuum.

There was somebody yelling and screaming behind me that he was killed and alarm bells were going off all over the place. You couldn't hear yourself think. The air-tight door to our bunk room slid across automatically and settled into its gaskets and we were locked in.

That scared me to death.

I know it has to be done. I know that it is better to seal off one compartment and kill the people who are in it than to let a whole ship die—but, you see, I was in that compartment, personally. I guess I'm just not the hero type.

I could feel the pressure sucking away at the plug my uniform made. With one part of my mind I was recalling that it had been advertised as "tropical weave, self ventilating" and wishing that it had been a solid plastic rain coat instead. I was afraid to stuff it in any harder, for fear it would go all the way through and leave us sitting there, chewing vacuum. I would have passed up desserts for the next ten years for just one rubber patch, the size of my hand.

The screaming had stopped; now it started up again. It was Noisy Edwards, beating on the air-tight door and yelling, "Let me out of here! Get me out of here!"

On top of that I could hear Captain Harkness's voice coming through the bull horn. He was saying, "H-twelve! Report! H-twelve! Can you hear me?"

On top of that everybody was talking at once.

I yelled: "Quiet!" at the top of my voice—and for a second or so there was quiet.

Peewee Brunn, one of my Cubs, was standing in front of me, looking big-eyed. "What happened, Billy?" he said.

I said, "Grab me a pillow off one of the bunks. Jump!"

He gulped and did it. I said, "Peel off the cover, quick!"

He did, making quite a mess of it, and handed it to me—but I didn't have a hand free. I said, "Put it down on top of my hands."

It was the ordinary sort of pillow, soft foam rubber. I snatched one hand out and then the other, and then I was kneeling on it and pressing down with the heels of my hands. It dimpled a little in the middle and I was scared we were going to have a blowout right through the pillow. But it held. Noisy was screaming again and Captain Harkness was still asking for somebody, anybody, in compartment H-12 to tell him what was going on. I yelled "Quiet!" again, and added, "Somebody slug Noisy and shut him up."

That was a popular idea. About three of them jumped to it. Noisy got clipped in the side of the neck, then somebody poked him in the pit of his stomach and they swarmed over him. "Now everybody keep quiet," I said, "and keep on keeping quiet. If Noisy lets out a peep, slug him again." I gasped and tried to take a deep breath and said, "H-twelve, reporting!"

The Captain's voice answered, "What is the situation there?"

"There is a hole in the ship, Captain, but we got it corked up."

"How? And how big a hole?"

I told him and that is about all there was to it. They took a while to get to us because—I found this out afterward—they isolated that stretch of corridor first, with the air-tight doors, and that meant they had to get everybody out of the rooms on each side of us and across the passageway. But presently two men in space suits opened the door and chased all the kids out, all but me. Then they came back. One of them was Mr. Ortega. "You can get up now, kid," he said, his voice sounding strange and far away through his helmet. The other man squatted down and took over holding the pillow in place.

Mr. Ortega had a big metal patch under one arm. It had sticky padding on one side. I wanted to stay and watch him put it on but he chased me out and closed the door. The corridor outside was empty but I banged on the air-tight door and they let me through to where the rest were waiting. They wanted to know what was happening but I didn't have any news for them because I had been chased out.

After a while we started feeling light and Captain Harkness announced that spin would be off the ship for a short time. Mr. Ortega and the other man came back and went on up to the control room. Spin was off entirely soon after that and I got very sick. Captain Harkness kept the ship's speaker circuits cut in on his conversations with the men who had gone outside to repair the hole, but I didn't listen. I defy anybody to be interested in anything when he is drop sick.

Then spin came back on and everything was all right and we were allowed to go back into our bunkroom. It looked just the same except that there was a plate welded over the place where the meteorite had come in.

Breakfast was two hours late and we didn't have school that morning.

That was how I happened to go up to Captain's mast for the second time. George was there and Molly and Peggy and Dr. Archibald, the Scoutmaster of our deck, and all the fellows from my bunk room and all the ship's officers. The rest of the ship was cut in by visiplate. I wanted to wear my uniform but it was a mess—torn and covered with sticky stuff. I finally cut off the merit badges and put it in the ship's incinerator.

The First Officer shouted, "Captain's Mast for punishments and rewards!" Everybody sort of straightened up and Captain Harkness walked out and faced us. Dad shoved me forward.

The Captain looked at me. "William Lermer?" he said.

I said, "Yessir."

He said, "I will read from yesterday's log: 'On twenty-one August at oh-seven-oh-four system standard, while cruising in free fall according to plan, the ship was broached by a small meteorite. Safety interlocks worked satisfactorily and the punctured volume, compartment H-twelve, was isolated with no serious drop in pressure elsewhere in the ship.

"'Compartment H-twelve is a bunk room and was occupied at the time of the emergency by twenty passengers. One of the passengers, William J. Lermer, contrived a makeshift patch with materials at hand and succeeded in holding sufficient pressure for breathing until a repair party could take over.

"'His quick thinking and immediate action unquestionably saved the lives of all persons in compartment H-twelve.'"

The Captain looked up from the log and went on, "A certified copy of this entry, along with depositions of witnesses, will be sent to Interplanetary Red Cross with recommendation for appropriate action. Another copy will be furnished you. I have no way to reward you except to say that you have my heart-felt gratitude. I know that I speak not only for the officers but for all the passengers and most especially for the parents of your bunk mates."

He paused and waggled a finger for me to come closer. He went on in a low voice, to me alone, "That really was a slick piece of work. You were on your toes. You have a right to feel proud."

I said I guessed I had been lucky.

He said, "Maybe. But that sort of luck comes to the man who is prepared for it."

He waited a moment, then said, "Lermer, have you ever thought of putting in for space training?"

I said I suppose I had but I hadn't thought about it very seriously. He said, "Well, Lermer, if you ever do decide to, let me know. You can reach me care of the Pilots' Association, Luna City."

From FARMER IN THE SKY by Robert Heinlein. 1950.

Suspended Animation

The ability to put crew members to sleep for months at a time would be an awfully convenient thing to have. Such crew members would use air and food at a much reduced rate and would not be prey to interplanetary cabin fever or space cafard.

Hibernation or "cold-sleep" would mimic what bears and squirrels do in the winter. The crewmember would sleep and breath slowly. Food would be administered by an intravenous pump or the body's internal fat could be used. The crew member still ages, abet at a slighly slower rate.

Suspended animation, cryo-freeze, or cryogenic suspension is more extreme. The crewmember is frozen solid in liquid nitrogen. They do not breath, eat, nor age. Special techniques must be used to prevent the ice in the body's cells from freezing into tiny jagged knives shredding the organs. This is naturally more dangerous than mere hibernation. It is generally used for slower-than-light interstellar exploration, or to put a crewmember with an acute medical condition into stasis if the ship cannot arrive at a hospital for some months.

Hibernation was shown in the movies Alien, 2001, and 2010. In William Tedford's Silent Galaxy AKA Battlefields of Silence, interplanetary fighter pilots would sometimes find themselves out of fuel and on trajectories that would take years to return to a spot where they could be rescued. They would use hibernation to stretch their consumables and to sleep the time away.

Poul Anderson noted that there is probably a limit to how long a human will remain viable in cryogenic suspension (in other words they have a shelf-life). Naturally occuring radioactive atoms in the body will cause damage. In a non-suspended person such damage is repaired, but in a suspended person it just accumulates. He's talking about this damage happening over suspensions lasting several hundred years, during interstellar trips. This may require one to periodically thaw out crew members and keep them awake for long enough to heal the damage before re-freezing them.

Hibernation and suspension is often encountered in SF novels where large numbers of people have to be shipped, e.g., troop carriers, slave ships, and undesirable persons shipped off as involuntary colonists to some miserable planetary colony. Some passenger liners will have accomodations of First-class, Second-class, and Freeze-class (instead of Steerage). There is often a chance of mortality associated with hibernation and suspension. In some of the crasser passenger ships there will sometimes be a betting pool, placing bets on the number of freeze-class passengers who don't make it.

He took out the little syringe, already loaded with the carefully prepared solution. Narcosamine had been discovered during research into animal hibernation: it was not true to say -- as was popularly believed -- that it produced suspended animation. All it caused was a great slowing-down of the vital processes, though metabolism still continued at a reduced level. It was as if one had banked up the fires of life, so that they smoldered underground. But when, after weeks or months, the effect of the drug wore off, they would burst out again and the sleeper would revive. Narcosamine was perfectly safe. Nature had used it for a million years to protect many of her children from the foodless winter.

From CHILDHOODS END by Sir Arthur C. Clarke

Hygiene

This brings up the question of how to use a toilet in free fall. I'm not going to go into the distasteful details, suffice it to say that "there ain't no graceful way".

Naoto Kimura mentioned that "Oh-gee Whiz" would be a good brandname for space toilet.

Bath and showers are very difficult in free fall. The crew will probably be reduced to sponge-baths or maybe a shower while zipped up in a bag. In Robert Silverberg's 1968 novel World's Fair 1992 he mentions "sonic showers" which use sound waves to remove dirt with no water required. And in Andre Norton's space novels, the bathing room is called the "fresher".

People who have gone camping are familiar with how surprisingly difficult it is to keep clean in the absence of running water. As do city-folk living in houses near a water main break who have to make do without tap water for a few days. You tend to take for granted the luxury of accessing unlimited amounts of water out of the faucet. In the space environment, water is strictly limited, and what water there is performs poorly as a cleansing agent in free fall.

For a longer period nothing more notable took place than the incident in which Roger Stone lost his breathing mask while taking a shower and almost drowned (so he claimed) before he could find the water cut-off valve. There are very few tasks easier to do in a gravity field than in free fall, but bathing is one of them.

From THE ROLLING STONES by Robert Heinlein (1952)

On a Soviet space station, Tanya freshens up.

Suspended nude in the air, she reached into her padded wall locker, braced a leg, opened the sliding panel and removed a plastic package from a box secured to an overhead shelf with velcro. She peeled away the wrapper, stuffing the plastic in the ever-ready disposal container, and opened a neatly folded, lightly scented towelette. Slowly and luxuriantly she removed the oily perspiration from her body. She smiled as the scent hovered about her. No Soviet quartermaster had ever issued these to the women cosmonauts who left the Earth behind! What she carried with her among her personal belongings were gifts from Susan Foster...

...Whatever their technical prowess, and Tanya knew it was most formidable, it was in the science of personal touch that the Americans were absolutely incredible. They were light years ahead of anything that emerged from Mother Russia. In the packages Susan gave her, concealed within a box supposedly filled with computer disks, were these sealed towels and their lightly scented fragrance, just enough to detect, and moist enough to clean and freshen her skin. It dried within seconds of its application and then you simply disposed of the towelette. She had hundreds of them. Some of the other women learned of her treasure and Tanya shared with them.

It made life infinitely more bearable after weeks and months in weightless orbit. It rendered personal hygiene a pleasure in a complicated, clanging, ear-stabbing vessel that reeked of oil, plastic, garlic and scallions and all manner of unpleasant body odors that soaked into the very "floors" and "walls" of station cubicles. The Americans, Tanya smiled, demanded their little luxuries wherever they went, and their woman cosmonauts were even more fiercely demanding than their men. Hooray for you, Tanya thought generously of the Americans. Long voyages into space with ships that stank left much to be desired, and if nothing else, the Americans were able to make of space adventure a mission that did not permanently wrinkle the nose...

...Susan slipped a personal package to Tanya...

..."How many are in here?"

"Four hundred."

"Tanya's eyes widened. "Four hundred?"

"We're the miracle workers of folded fragrance."

From EXIT EARTH by Martin Caidin (1987)

Keeping the habitat module clean is also a challenge. Water is limited, water does not clean things very well in free fall, and the limited atmosphere prevents one from using any alternate cleanser that it toxic or has a disagreeable odor.

And as mentioned elsewhere, any free floating garbage tends to accumulate on the air-intake vents. The vents on the Skylab space station quickly became quite disgusting with random bits of rotting food and dust particles.

One of the shipboard roaches woke Lindsay by nibbling his eyelashes. With a start of disgust, Lindsay punched it and it scuttled away.

... He shook another roach out of his red-and-silver jumpsuit, where it feasted on flakes of dead skin.

He got into his clothes and looked about the gym room. Two of the Senators were still asleep, their velcro-soled shoes stuck to the walls, their tattooed bodies curled fetally. A roach was sipping sweat from the female senator's neck.

If it weren't for the roaches, the (spacecraft) Red Consensus would eventually smother in a moldy detritus of cast-off skin and built-up layers of sweated and exhaled effluvia. Lysine, alanine, methionine, carbamino compounds, lactic acid, sex pheromones: a constant stream of organic vapors poured invisibly, day and night, from the human body. Roaches were a vital part of the spacecraft ecosystem, cleaning up crumbs of food, licking up grease.

Roaches had haunted spacecraft almost from the beginning, too tough and adaptable to kill. At least now they were well-trained. They were even housebroken, obedient to the chemical lures and controls of the Second Representative. Lindsay still hated them, though, and couldn't watch their grisly swarming and free-fall leaps and clattering flights without a deep conviction that he ought to be somewhere else. Anywhere else.

From SCHISMATRIX PLUS by Bruce Sterling (1996)

(ed note: The Christmas Bush is a Fractal Robot. Tiny parts can be separated to be small robots "sub-motiles")

Now, let me show you some of its other tricks." He reached into his shirt pocket and pulled out a pressurized ball-point pen. He then unbuttoned his shirt front and used the pen to push out a bit of lint from behind a button-hole. He kicked over to a nearby wall and deliberately made an ink mark on the wall. As he kicked back, he let loose the bit of lint into the air. As he came to a halt back with the group, they watched as two tiny segments of the Christmas Branch detached from one of the arms. The smaller one, a minuscule cluster of cilia not much bigger than the bit of lint, flew rapidly through the air with a humming sound like that of a mosquito, captured the floating ball, and flew out the door to another part of the ship, zig-zagging as it went.

"It's picking up other bits of dust on its way to the dust-bin," explained David. "They're too small for us to see, but its little laser radars picked them up from their backscatter."

The larger sub-motile jumped from the Christmas Branch to the wall, and like a spider, used its fine cilia to cling to the wall and walk over to the ink smudge. The cilia scraped the ink out of the wall pores and formed it into a drying ball. The wall now clean, a sub-section of the spider detached and swam off through the low gravity, while the remainder of the spider jumped back to the Christmas Branch where it resumed its normal place.


"Yet housekeeping is a continual chore, so don't be surprised if you see a mosquito flying through the air or a spider walking across the ceiling. They will just be collecting all the dirt and dust you've made that day."


The Christmas Bush was busy weaving cloth using a bright green artificial thread that it had reconstituted from the lint fibers it had collected over the past years.

From Rocheworld by Robert Forward (1982)

Human Factors

The space environment is so inconvenient for human beings. There is so much that one has to bring along to keep them alive.

Life Support has to supply each crew member daily with 0.0576 kilograms of air, about 0.98 kilograms of water, and about 2.3 kilograms of (wet) food (less if you are recycling). Some kind of artificial gravity or a medical way to keep the bones and muscles from wasting away. Protection from the deadly radiation from solar storms and the ship's power plant and propulsion system. Protection from the temperature extremes in the space environment. Protection from acceleration. Medical support. And then there are the psychological factors.

Recently John Lumpkin and I were allowed the rare privilege of submitting questions to NASA astronaut Captain Stephen G. Bowen a couple of questions about life in the space environment.

Me: My main interest are those details about living in a space environment that are "surprising", that is, not intuitively obvious to us earth-bound folk.

Captain Bowen: The most surprising thing is how quickly you adapt to being in the microgravity environment. In addition to floating around the rest of the body adapts pretty quickly (after about 4 days all systems are good). The fluid shift resolves and you lose the puffy face in week. The ISS crewmembers say at about the 6 week point it feels normal to live in space (consequently it takes 6 weeks before earth feels normal). Other than that it takes a while to realize that you can't just put things down and instead of looking down for things you lose you have to look all around.

John Lumpkin: I guess I'd be curious about the little things of life in freefall. Stuff he has to get used to in terms of eating, sleeping, changing clothes, moving around, and so on. Is it easy to hit your head on things? To fly into other people? What are some things that work on Earth but don't in freefall ... Particularly things most people might not think of? This sort of thing makes nice color for antigrav-free science fiction stories.

Captain Bowen: One of the interesting things once you do get adjusted in space is how you think you know how to float and translate. On the Shuttle your never very far from anything so you get really good in a couple days. Once you dock to the ISS however, it is huge. You quickly realize that your not that good and it takes a while to get good at translating 40 feet or so without bumping off the walls (experiments, cables etc...) with different body parts (feet, head, back...) Additionally you can actually try and get yourself into a position where you are stationary and can't reach anything -that is an interesting feeling since swimming in air to get someplace is very inefficient. Other interesting things - you can eat your tea with chopsticks, you can sleep in any configuration, and since dust and debris don't fall it all collects on the intakes of the fans (for the most part but it is odd to watch such things just floating about). One night the ISS bell floated down from the ISS to the middeck of the Shuttle (right past me) without anyone noticing till we woke up the next morning.

John Lumpkin: The Russian/Chinese philosophy on spacecraft design is to make the re-entry capsule small, allowing for less of the total launch mass to be devoted to re-entry protection. This frees up mass for use in the non-re-entering work module, allowing greater capability there. The US philosophy, for both Apollo and Orion, is to put the entire crew area within the re-entry capsule. I understand the advantages to the Russian/Chinese approach -- what compelling advantages are there to the US approach?

Captain Bowen: I've not been a part of the design work. My one input was to get rid of windows. Both Apollo and Orion while more spacious are actually not designed for long term living. Apollo had the additional space once the Lunar module was attached and Orion will have a docked module launched separately for transit to the Moon. For shorter missions (such as going to the ISS) you won't need the extra space. Orion is really sized for launch and reentry of 6 suited astronauts with a specific blunt body shape. We also don't have the same size restrictions the others have for astronauts. Everything else is squeezed around the seats, and for the moon the crew size is reduced to provide more room. I really haven't thought about the size relative to Soyuz other than Soyuz is really tight.

John Lumpkin: How hot can you make that coffee in a microgravity environment? How hot is the food? Do you sleep better (microgravity) or worse (noise) in orbit? How much time do you spend on maintenance? How well do international partners get along in space? Do the people in space get along better than the two ground stations (US and Russia)?

Captain Bowen: The pressure on the ISS and Shuttle are 14.7 just like here. Although the Hubble mission will be at 10.2 for its entire mission for EVA reasons. The hot water does get really hot. The convection oven is pretty hot as well. I averaged about an hour more sleep on orbit than on earth. We all get along really well. The ISS crews train for years with their crewmates and we've all worked with them as well. Some of the ESA and JAXA and CSA astronauts are permanently stationed in Houston. The Cosmonauts we see in Russia and occasionally as they pass through Houston. Yes I think we get along better in space - but then again we know each other better than the ground teams do.

Space Medicine

(ed note: Cot-Vee = Cargo Orbital Transfer Vehicle {COTV}, Pot-Vee = Personnel Orbital Transfer Vehicle {POTV})

"Okay, T.K., look at it this way. Those three hundred people in LEO Base can get back to Earth in less than an hour if necessary; we'll have lifeboats, so to speak, in case of an emergency. But out there at GEO Base, it's a long way home. Takes eight hours or more just to get back to LEO, where you have to transfer from the deep-space passenger ship to a StarPacket that can enter the atmosphere and land. It takes maybe as long as a day to get back to Earth from GEO Base— and there's a lot of stress involved in the trip."

Hocksmith paused, and seeing no response from the doctor, added gently, "We can get by with a simple first-aid dispensary at LEO Base, T.K., but not at GEO Base. I'm required by my license from the Department of Energy as well as by the regulations of the Industrial Safety and Health Administration, ISHA, to set up a hospital at GEO Base."

He finished off his drink and set the glass down. "If building this powersat and the system of powersats that follow is the biggest engineering job of this century, T.K., then the GEO Base hospital's going to be the biggest medical challenge of our time. It'll be in weightlessness; it'll have to handle construction accidents of an entirely new type; it'll have to handle emergencies resulting from a totally alien environment; it'll require the development of a totally new area of medicine— true space medicine. The job requires a doctor who's worked with people in isolated places—like the Southwest or aboard a tramp steamer. It's the sort of medicine you've specialized in. In short, T.K., you're the only man I know who could do the job . . . and I need you."


John Curry, comptroller of Eden Corporation, looked disturbed as he scanned the sheet of budget figures Tom had submitted to him several days before. "Doctor, I didn't realize you'd have to set up a complete hospital at GEO Base."

"We'll need a complete trauma center, as well as an intensive care unit," Tom explained. "I'll also have to be prepared to handle something more than runny noses; I'll need a pathology lab and a blood lab. I'll need radiology equipment because I can't send an employee back to the Jornada with broken bones I don't know about; the accelerations of return and atmospheric entry could kill a person if we didn't know where the break was and take steps to protect him against acceleration. If we could let him come back to Earth at all. We might have to let him heal up there."

Curry drummed his fingers on his desk top while he studied the budget sheet once again. "But a ten-bed hospital? Isn't that rather large for a construction-site operation, Doctor?"

"That's fewer beds per thousand people than the state of New Mexico has right now—and you know this state's desperately short of hospital beds," Tom told him bluntly. "I'm going to be twenty-two thousand miles away with no possibility of getting help in an emergency and no way to get an injured or sick person back to the ground in less than a day. And those time estimates are under the best conditions with Pot-Vees and StarPackets on hand and ready to move."


"The cost of the equipment doesn't bother me," Curry went on. "We'll work that out so it's a capital expense properly written off in a way that'll keep the IRS happy and the government auditors pleased. What's difficult is the cost of getting the equipment there." (ed note: every gram counts)

"I know," Tom admitted. "That's why I've tried to choose equipment that weighs as little as possible. In some cases I've specified new equipment that has yet to be tried and proved. I've got to take certain risks, however, because I understand the costs of getting the equipment to GEO Base as well as the costs in terms of electrical and cooling energy to operate it once it's there." He was glad that Dan Hills had been so helpful in going over the engineering aspects of his GEO Base clinic. Things he took for granted on Earth became serious problems at GEO Base. For example, he had to consider thermal efficiency of equipment, since the heat load of GEO Base had to remain in balance. Calories coming in had to balance calories going out; otherwise, equipment heat losses would literally burn the place up. The drawings of the GEO Base hospital already showed the hex module festooned with heat radiators.

"I wish there were some way to beat some of these lift costs," Curry remarked, shaking his head. "When we get rolling on the two-per-year production phase, that won't be so important. But the start-up costs of this pilot-plant phase are all out of proportion."

Tom thought about how he might have to handle things at the H-Bar-S Ranch if there were a number of injured or sick people and no way to get equipment in or patients out. It was a problem he had faced before. "Uh, John, maybe I can skimp a few things to start with if have outstanding communications links."

Curry began to nod slowly. "I think I see what you mean, Doctor. GEO Base will have a communications capability with a large number of broad-band, high bit-rate channels. Uh, would a high bit-rate computer link and an interactive video system help?"

"That's what I was thinking about," Tom acknowledged.

"What could you eliminate if you had good communications capabilities?"

"Some of the analysis equipment. If I have rapid access to one of the medical computer networks, I could squirt raw data to lab facilities here on Earth. I could also eliminate most of that microfilm medical data I specified, because then I could tie in with any computerized medical library here ... or I could go interactive on a video channel with one or more specialists if I ran into something where I needed consultation."

Curry reached down into his desk, pulled his terminal to desk-top level, keyed it, and looked at the display. "We can set you up with any number of nets. How about GALEN—General Analytical and Library Electronic Network?"

"Never heard of it."

"One of the best medical nets going, it says here."


Tom had worked out eight basic medical areas he would have to be prepared for. First, there were the usual job-related injuries that were physical: cuts, bruises, burns, abrasions, and even severed limbs. Then there were the pathological aspects, basically public health measures to block entry of infectious bacteria and viruses into space facilities as well as to counteract them when they did sneak in, as they always managed to do.

He also had to be prepared for what he termed the congenital afflictions—appendicitis, tonsilitis, cholecystitis, toothaches, etc. There would also be stress-related illnesses manifesting themselves in hypertension, cardiac problems, and psychosomatic conditions—plus psychological problems caused by isolation and phobias such as the one Ross Jackson had mentioned with the Gemini astronaut.

He had to keep watch for biochemical problems that might be exacerbated or brought on by dietary deficiencies, glandular imbalances, and so forth, plus the medical problems created by social interaction, because there were certain to be fights and alcoholism, and even some drug abuse, strict as the preflight inspection might be. Tom knew enough about human nature to realize somebody would either manage to sneak the stuff up or cobble together a vacuum still.

But the biggest problems were still environmental, the medical aspects of the space environment itself. At GEO Base, he knew he couldn't take a lot of things for granted, earthly things like food, water, temperature, atmosphere, and radiation. These were items that really had him worried.


Four people were jammed into First-Aid when he arrived, and the place was filled with a pink mist. All four people wore pressure suits, but three were without helmets. The exception was a short, stocky person whose utterly relaxed position, afloat in the compartment, spelled "unconscious" to Tom.

"Get that off!" Tom snapped to a young woman who was holding the man by his pressure helmet. "What happened here?' Then he saw that the right leg of the man's pressure suit terminated at the lower end of the calf, just above the ankle. So that was the source of the pink mist.

"Fred was working on the power-control junction and must have had a suit radio failure," the young woman remarked. There was no panic in her voice. "Some yo-yo was trying to mate the attach points of another submodule, and he didn't see Fred's leg in the way. When I saw it and yelled, Fred didn't hear me. His radio must have been out."

The man's foot was sheared through just above the ankle, and it had not been a clean severance. Somebody had acted fast out there, and the conipartmentation of the pressure suit had saved the man. A rough tourniquet of electrical cable had been wound around his leg, the only thing that had prevented the pressure in his suit from pumping all his blood out into vacuum. Nonetheless, he had lost a lot of blood.


Moving in a hurry in weightlessness was difficult and bordered on the impossible because Tom wasn't used to it. Several times he pushed off too robustly and ended up banging hard against bulkheads or cabinets. The equipment he removed from cabinets wouldn't behave itself. Fitzsimmons was in shock, and it was important that Tom get oxygen and stimulants into the man immediately, but the hose on the oxygen mask wound itself all over the place. Finally, with Lucky Hertzog's help, he managed to get the oxygen mask securely in place.

There was no way that an IV was going to work, Tom discovered. Without gravity, it wouldn't drip. He thought of injection, then discovered he couldn't get the air bubbles out of the syringe in the usual manner. He ended up swinging it at the end of his arm and squirting most of the injection into the compartment before he felt it had been deaerated enough to prevent an embolism. Getting the IV working was strictly a lash-up, and he didn't have time to be neat. He had to start lactate of Ringer going right away, followed by whole blood—if there was any—followed by closing or cauterizing the severed blood vessels that, in spite of the tourniquet, were still seeping. He called in one of the men from the passageway and instructed him on how to inject the IV solution gently and slowly into Fitzsimmons' arm.

No whole blood was available in the First-Aid Center. Tom cursed himself for not specifying that there be some. It was, therefore, vitally important that he tie off the blood vessels as quickly as possible.


When Torn couldn't find any sutures in the cabinets, he yelled for the remaining man waiting in the passageway. "You, get up to my quarters and bring back my flight kit. I don't know the compartment number—ask a steward. And hurry!"

After ten minutes passed and the man had not returned, Tom was in a bind. He had to stop the bleeding. "I've got to cauterize! Is there a welding torch around here?"

"Nobody in his right mind would do oxyacetylene welding here," Lucky told him.

"If I don't, this man's going to die from blood loss!"

"How about an arc welder?"

"Get it in here!" Tom didn't know how he was going to cauterize the stump of a leg with an electric arc welder, but he would try to figure something out. Unfortunately, there wasn't an arc welder within three hex modules of First-Aid.

Tom didn't panic, but he was slowly coming to the conclusion that his worst fears would be realized. He was going to lose this man because he hadn't been able to assess the medical requirements of a space facility accurately.

Lucky Hertzog released Fitzsimmons' head and moved toward the compartment door, maneuvering easily in zero-g.

"Where are you going?" Tom asked.

"You've got to seal that stump, right?"

"Right, but—"

"I'm going over to the beam builder three modules away. I'll bring back enough activated epoxy to cover that whole stump." And she was gone.

But the man returned with Tom's bag before Lucky did. Tom kept packaged sutures and needles in his kit, along with the necessary surgical tools. He always tried to go prepared to handle emergencies, a habit born from his life in the Southwest, where towns and doctors were far apart.

Tom was in the process of tying off arteries when Lucky Hertzog floated in, both hands full of a lump of curing epoxy.

"How long before that cures?"

"About fifteen minutes, Doc. It's got maybe ten minutes' working life left."

"Okay, I can get these arteries tied off by then. Stand by."

But doing so wasn't as easy as he had thought. Blood spurted everywhere. It was almost impossible to keep the working area clear of blood, which formed drops and globules, its surface tension making it creep along the exterior of every object it touched. But he managed to get the main arteries tied, then formed a base to the stump with the glob of epoxy.

The procedure worked. The blood flow stopped, and Tom was able to remove the tourniquet. It hadn't been sterile, and it hadn't been neat, but Fitzsimmons was still alive.

Then his heart stopped in shock from general loss of blood.

"CPR!" Tom snapped.

He quickly discovered CPR wouldn't work in weightlessness. When he punched down on Fitzsimmons' chest, he and Fitzsimmons flew apart.

Lucky quickly jammed Fitzsimmons' body into a locker along one side of the compartment and jammed herself in with him. With her back against one side of the locker and his against the other, she began CPR.

"Spell me," she gasped to Tom after about five minutes, during which time he had been trying to get the leads of the defibrillator untangled. One of her men moved in and took over, leaving Tom to his struggle.

But between Lucky Hertzog and her two workers, they managed to get Fitzsimmons' heart going again without the need for Tom to defibrillate—a risky business in the metal-walled compartment.


From Space Doctor by Lee Correy (G. Harry Stine) 1981

Old Astronaut Syndrome

There are some maladies that afflict people who spend prolonged periods in microgravity, exposed to space radiation, and exposed to radiation from nuclear propulsion. These could be characteristic signs of space traveling old-timers.


The most obvious effect of microgravity is the astronaut's muscles atrophy and the shedding of calcium by their bones (1% to 1.5% per month, like osteoporosis). Being weak with brittle bones isn't lethal but presumably the astronauts at some point want to return home to Terra and still be able to walk. Science fiction literature is full of mandatory exercise to combat this, with "exercise credits" awarded for time spent under acceleration and in centrifuges. NASA astronauts on the International Space Station have to exercise two hours a day for this reason. Some astronauts (or colonists of low gravity planets and moons) might require man-amplifier prosthetics in order to walk under a full Terran gravity.

Naturally such space osteoporosis can lead to kidney stones, the agony of which is the closest a male will ever come to the sensation of giving birth. Space osteoporosis can also be combated by exercise.

Astronaut's eyes are especially vulnerable. Recently NASA made the horrible discovery that exposure to microgravity for six months or longer causes permanent damage to the eyes, similar to idiopathic intercranial hypertension. There is some evidence that this is due to enzyme polymorphisms that increases astronaut vulnerability to bodily fluid shift in free fall.

And a science fictional favorite is the microgravity adapted astronaut who when on Terra has a tendency to let go of glasses of water in mid air, expecting them to float.


The two main effects of radiation on an astronaut are [1] cancer and [2] death by radiation sickness. You are unlikely to encounter an old astronaut suffering from [2] unless you like to visit graveyards. But the probability is high that most old astronauts will have undergone treatment for cancer at one time or another. Probably several times. NASA tries to avoid this by ensuring that there are no old astronauts. NASA has strict career limits on astronaut radiation exposure.

Secondary effects of radiation are skin ulceration and blindness due to cataracts scarring. High-mass, high-charged (HZE) cosmic rays might accelerate the development of Alzheimer's disease. Radiation also lowers the immune system (chromosomal aberrations in lymphocytes), but it can recover.

Atomic rocketeers on board an atomic rocket will also without fail have a package of potassium iodide tablets on their persons at all times. Why? If the reactor core is breached, the mildly radioactive fuel and the intensely radioactive fission fragments will be released into the atmosphere. While none of the fission fragment elements are particularly healthy, Iodine-131 is particularly nasty. This is because ones thyroid gland does its level best to soak up iodine, radioactive or not. Thyroid cancer or a hoarse voice from thyroid surgery might be common among atomic rocket old-timers. The tablets prevent this by filling up the thyroid first, before the Iodine-131 arrives. The instant the reactor breach alarm sounds, whip out your potassium iodide tablets and swallow one.

"What's you doing up here, Lucky? I thought you were on your way down to LEO Base in the Edison with Ross."

"I was, except I didn't think Ross was in fit shape to drive," Lucky explained.

"What's wrong, Ross?"

The astronaut looked pained. "Had a dizzy spell during preboost checkout, and this redheaded broad, who's a big fan of yours, insisted I come and give you some business."

"Are you still dizzy?"

"A li'l bit." Ross' speech was thick and slurred.

"You didn't bust Rule Three, did you?"

"No, Doc—nothin' alcoholic in the last twenty-four hours. Just like the rule says. Why's everybody think I'm drunk or somethin'? Dammit, gettin' so nobody around here trusts me anymore!"

There was no alcohol on Jackson's breath. "What'd you have at your last meal?"

"Nothin'. Not hungry. Hey, can I use your lav? I gotta take a leak bad." He pushed off in the direction Tom pointed to.

Lucky looked at Tom with concern. "Tom, I've never seen Ross this way before. It wasn't just the dizziness. We all get a little disoriented every once in a while. If it had been just that, I would've boosted with him. But not when he's in this condition."

"I agree with you, Lucky." Tom turned to Jackson as the astronaut floated back from the lavatory. "Ross, do you have an alternate to take your flight?"

"Sure!"

"Okay, I'm admitting you to sick bay here for a checkup."

"Hell, Doc, I'm all right! Just give me something for this dizziness and for my upset stomach, and I'll be good as new!"

"You're nauseated? Stomach hurts?"

"Yeah. Don't ground me, Doc! I've never failed my physical!"

"I'm not grounding you, Ross. I want to check you to find out if there's anything wrong with you. If there isn't, you'll get a clean bill from me. Okay?"

"Yeah, okay, but I'm getting damned tired of everybody pickin' on me! Jeez, I've got more time in space than any of you! I'm not gonna run off at the ears and do somethin' that'll kill me or anybody else!"

"I know you're not. Dorothy, let's get urine and blood samples from Ross. And give him ten milligrams of prochlorperazine IM to take care of his nausea and stomach cramps."


Tom left Jackson in Dorothy's watchful care and went to the GALEN terminal. He called up Ross Jackson's medical records.

The former NASA shuttle pilot was forty-seven years old. The record showed he had never varied from the medical norm during his entire flying career with the Air Force, NASA, or, now, SpaceLift, Inc. Tom went back through thirty-one years of medical records to Ross' initial FAA Third Class physical exam as a student pilot. There was nothing in the man's background that would lead Tom to suspect anything abnormal.

Was his problem something that resulted from thousands of hours spent in zero-g—the first symptoms of some syndrome that hit old-timers in space, something that would limit mankind's ability to live in space for long periods?

Tom gave that possibility a low priority. He knew many strange maladies affected human beings. He refused to jump to conclusions until Dave Cabot finished the urine and blood analyses and came up with some concrete data on which to base a diagnosis.


Dave was getting good at body-fluid lab work-ups. He was mastering the new tricks he had had to work out for handling liquids in weightlessness, using surface-tension effects and wetting characteristics to their fullest extent to control the liquids. It took him less than an hour to compile the complete data.

And it didn't make sense to Tom.

There was a slight electrolyte imbalance, but nothing beyond what he saw every day in the analysis of his staff's physiology.

The work-up showed a slight hypoglycemia, which might presage the onset of diabetes mellitus but which was not reflected in the urine sample. Tom had thought about this possibility. Ross was of the age when the disease could manifest itself. But the other symptoms weren't present. And the man said he hadn't eaten recently, which could also explain the low glucose level in the urine sample as well as the low blood-sugar level.

Ross couldn't be suffering from anorexia. By reputation the astronaut was something of a trencherman, and he did have difficulty keeping his body mass under control. Ross showed no tendency toward obesity; he just liked to eat well.

Serum calcium level was 12.1 milligrams per hundred milliliters—high, but not beyond what Torn saw occasionally, usually that was because of calcium resorption in the blood resulting from calcium loss in the bones.

Urine PH normal. Everything within normal range except for the usual suppression of steroids and increases in primary hormone levels associated with orbital living.

"Damn!" he swore under his breath.


Tom keyed the terminal and fed in the blood and urine data. He then typed in the observed symptoms and called for a probable diagnosis.

As usual, GALEN was fast. Almost as quickly as he had hit the RUN key, it flashed its answer across the screen:

FIRM DIAGNOSIS NOT POSSIBLE WITH DATA PROVIDED. DIAGNOSIS ONE OF THREE POSSIBILITIES: 1. ADDISON'S DISEASE, BUT DATA INDICATING INCREASED PIGMENTATION OF THE DERMIS AND DISCOLORATION OF ORAL AND NASAL MUCOUS MEMBRANES NOT PROVIDED. 2. HYPER-CALCEMIA, BUT DIAGNOSIS REQUIRES CONFIRMATION THAT Q-T INTERVAL OF ECG IS SHORTENED. 3. DIABETES MELLITUS, EXCEPT URINALYSIS DOES NOT TOTALLY SUPPORT THIS AND THEREFORE POSSIBILITY MUST BE CONSIDERED REMOTE. PLEASE PROVIDE ADDITIONAL DATA FOLLOWING POSSIBILITY NUMBER GIVEN ABOVE. STANDING BY.

"Dorothy, warm up the ECG," Tom called.

Ross revived at this and understood what Tom was talking about. "Oh, no, Doc! Not my heart! I haven't got chest pains! I've got gut pains."

"Don't worry, it's not your heart, but I have to check your ECG to confirm a diagnosis," Tom tried to reassure him.

In less than five minutes, Tom had the answer.

"There it is: shortened Q-T interval on the electrocardiogram." He showed the printout to Ross.

"What's that mean, Doc?" The anxiety in the astronaut's voice penetrated the lethargy that the relaxant drug had caused.

"Hypercalcemia. I'd call it the Ancient Astronaut Syndrome. You've been in weightlessness more than anyone else in GEO Base, Ross. All of us are suffering from some decalcification of our bone mass because our skeletons aren't supporting the weight of our bodies. The calcium is resorbed into the cellular fluid and then into the blood serum. You're reacting in a textbook manner to the fact your body's having trouble getting rid of the excess calcium being poured into your system from your bones."

"Will it ground me?" Ross asked

"I won't ground you, Ross, because I can treat this syndrome," Tom told him. "It's no more incapacitating than any endocrine imbalance, and it can be treated and controlled. People are flying airplanes all over the world with hyperthyroidism, hypothyroidism, hyperuricemia, and a whole list of other endocrine and metabolic disorders. Chemotherapy solves their problems and permits them to function normally. I'm going to do the same for you and put you on fifty milligrams of prednisone every day; you'll just have to take a pill every time you have breakfast. You're the first case of hypercalcemia I've seen in space. Frankly, you're going to be a guinea pig for the rest of us. For right now, I want to keep you here under observation for twenty-four hours—just to make sure I'm right. Then I'll clear you to flight status, but only for a single mission to LEO Base and back. You've got to report back here for a quick test every time you hit GEO Base. Understood?"

"Roger your last, Doc! Hey, thanks. I know doctors who'd ground me for less than this." Relief was evident in his voice. "Doc, you can use me as a guinea pig any time you want," Ross said.

From Space Doctor by Lee Correy (G. Harry Stine) 1981

Drop Sickness

Space Adaptation Syndrome aka "drop sickness" is a kind of motion sickness caused by weightlessness. Outer space sea-sickness, so to speak. Symptoms include dizziness, fatigue, nausea, vomiting, and an inability to care about anything but your own private world of pain. The joke is drop sickness makes you feel like you are going to die, and you are actually looking forwards to it.

About half of new astronauts suffer from drop-sickness when they first travel into space. Of those who suffer, 50% have mild symptoms, 40% have medium, and 10% have severe. The most severe that NASA ever recorded was that of Senator Jake Garn in 1985. They jokingly use the "Garn scale", where 1.0 Garn is the worst.

Drop sickness usually goes away after two to four days exposure to free fall. Occasionally there is a relapse, which can happen at any time. When suffering from drop sickness, be careful not to rapidly turn or shake your head. This will make the fluid in the inner ear slosh and make things much worse.

Novice NASA astronauts do not take motion-sickness medication on their first trip into orbit. It is considered better for them to be miserable for a day or two but actually adapt to become immune. This is also the reason NASA never schedules EVAs for the first two days of a mission.

Having said that, NASA astronaut always put on a transdermal dimenhydrinate anti-nausea patch when suiting up in a space suit, because throwing up inside a suit can be fatal. A little dramamine is much better than suffocating to death in a vomit-filled helmet.

Drop sickness can be avoided if the spacecraft or station has artificial gravity, though that creates more problems.

What is so funny about a man being dropsick? Those dolts with cast-iron stomachs always laugh — I'll bet they would laugh if Grandma broke both legs.

I was spacesick, of course, as soon as the rocket ship quit blasting and went into free fall. I came out of it fairly quickly as my stomach was practically empty — I'd eaten nothing since breakfast — and was simply wanly miserable the remaining eternity of that awful trip. It took us an hour and forty-three minutes to make rendezvous, which is roughly equal to a thousand years in purgatory to a ground hog like myself.

I'll say this for Dak, though: he did not laugh. Dak was a professional and he treated my normal reaction with the impersonal good manners of a infight nurse — not like those flat-headed, loud-voiced jackasses you'll find on the passenger list of a Moon shuttle. If I had my way, those healthy self-panickers would be spaced in mid-orbit and allowed to laugh themselves to death in vacuum.

Despite the turmoil in my mind and the thousand questions I wanted to ask we had almost made rendezvous with a torchship, which was in parking orbit around Earth, before I could stir up interest in anything. I suspect that if one were to inform a victim of spacesickness that he was to be shot at sunrise his own answer would be, "Yes? Would you hand me that sack, please?"


"Dak?" I said as he signed off.

"Later," he answered. "I'm about to match orbits. The contact may be a little rough, as I am not going to waste time worrying about chuck holes. So pipe down and hang on."

And it was rough. By the time we were in the torchship I was glad to be comfortably back in free fall again; surge nausea is even worse than everyday dropsickness.

From DOUBLE STAR by Robert Heinlein, 1956

(ed note: Mercer is the doctor/steward on a passenger NTR spacecraft headed for the Jovian moons)

"The passengers are settled in, sir," said the darkhaired one. "All have been given medication, but you might keep an eye on Mr. Saddler and Mr. Stone, who may be trying to prove something—I think they palmed their capsules."

Mercer nodded without speaking.


"Are you comfortable, Mr. Saddler?" Mercer said pleasantly to the next in line; then he stopped. This was one of the tough guys who had not taken his medication. Mercer stared at the man's face without really seeing it while his mind sought in vain for a pleasant and friendly way of telling him to take his and-nausea pill and not be a fool. By the end of the allotted minute Mercer still did not have the answer, and he saw that the passenger's face was becoming apprehensive and that he was refusing to meet Mercer's eyes. Suddenly he wriggled sideways in his straps so that he could reach his breast pocket.

"I'm sorry," he mumbled, "I nearly forgot to take my pill."

"It can happen," said Mercer pleasantly, "in the excitement."


The next couch was empty, for the very good reason that it was his own. Beyond it was the one belonging to Stone, the other passenger suspected of missing out on his pre-takeoff medication. Mercer tried the blank stare on him that had worked so well with Saddler, hoping that the man's guilty conscience would do the rest, but Stone simply stared back at him. Maybe his conscience was clear. Mercer had to be content with clearing his throat loudly and slipping a plastic bag between the other's chest straps where Stone could reach it quickly.


Mercer spent the time checking that the vacuum cleaner under his couch was handy and worrying about the period of weightless maneuvering, which would begin when they went into Earth orbit. Both the book and his instructor had painted awful pictures of weightless nausea running wild. It could become critical, they had said, a chain reaction, which could spread even to those who had taken medication, and the job of clearing the air was difficult and distasteful. An incident like that was the one thing guaranteed to sour the whole voyage.


Someone grunted and gave an odd-sounding cough. Mercer swung around to see the passenger called Stone rapidly filling his plastic bag. Stone had been a little late in getting the bag to his mouth, and some of the material was drifting above his couch where the next surge of acceleration would send it flying all over the place. With his feet still held by the webbing Mercer unclipped the sucker from the underside of his couch and went after the stuff, pulling it into the small but powerful vacuum cleaner and leaving in its place a fresh smell of pine trees and heather. Then he helped Stone until he was quite finished, sponged his face and produced a water tube and an anti-nausea pill.

"Sorry about that, Mr. Stone," he said drily, "but there are some people who seem to need double the usual medication."

As he swallowed it, Stone had the grace to blush.

From Lifeboat by James White (1972)

The ship's loudspeaker blatted out, "All hands! Free flight in ten minutes. Stand by to lose weight." The Master-at-Arms supervised the rigging of grab-lines. All loose gear was made fast, and little cellulose bags were issued to each man. Hardly was this done when Libby felt himself get light on his feet — a sensation exactly like that experienced when an express elevator makes a quick stop on an upward trip, except that the sensation continued and became more intense. At first it was a pleasant novelty, then it rapidly became distressing. The blood pounded in his ears, and his feet were clammy and cold. His saliva secreted at an abnormal rate. He tried to swallow, choked, and coughed. Then his stomach shuddered and contracted with a violent, painful, convulsive reflex and he was suddenly, disastrously nauseated. After the first excruciating spasm, he heard McCoy's voice shouting.

"Hey! Use your sick-kits like I told you. Don't let that stuff get in the blowers." Dimly Libby realized that the admonishment included him. He fumbled for his cellulose bag just as a second temblor shook him, but he managed to fit the bag over his mouth before the eruption occurred. When it subsided, he became aware that he was floating near the overhead and facing the door. The chief Master-at-Arms slithered in the door and spoke to McCoy.

"How are you making out?"

"Well enough. Some of the boys missed their kits."

"Okay. Mop it up. You can use the starboard lock." He swam out.

McCoy touched Libby's arm. "Here, Pinkie, start catching them butterflies." He handed him a handful of cotton waste, then took another handful himself and neatly dabbed up a globule of the slimy filth that floated about the compartment. "Be sure your sick-kit is on tight. When you get sick, just stop and wait until it's over." Libby imitated him as best as he could. In a few minutes the room was free of the worst of the sickening debris. McCoy looked it over, and spoke:

"Now peel off them dirty duds, and change your kits. Three or four of you bring everything along to the starboard lock."

At the starboard spacelock, the kits were put in first, the inner door closed, and the outer opened. When the inner door was opened again the kits were gone — blown out into space by the escaping air. Pinkie addressed McCoy.

"Do we have to throw away our dirty clothes too?"

"Huh uh, we'll just give them a dose of vacuum. Take 'em into the lock and stop 'em to those hooks on the bulkheads. Tie 'em tight." This time the lock was left closed for about five minutes. When the lock was opened the garments were bone dry — all the moisture boiled out by the vacuum of space. All that remained of the unpleasant rejecta was a sterile powdery residue. McCoy viewed them with approval. "They'll do. Take them back to the compartment. Then brush them — hard — in front of the exhaust blowers."

From "Misfit" by Robert Heinlein (1939)

Boredom

Several SF novels point out the dangers inherent in cooping up people in a tin can surrounded by vacuum for months at a time. They will be prey to "space cafard" (i.e., deep space cabin fever, what the French Foreign Legion called "the beetle"). The only solutions seem to be [a] put them in the suspended animation freezer, [b] drug them, or [c] keep them busy, busy, busy! (a bi---, er, ah complaining spacer is a happy spacer) The first officer can assign some worthless busy-work, like a once daily nose to stern ship inspection for micro-meteor holes. One might think that the same problem would be faced by the crew on a military submarine, but as it turns out the analogy is inexact. Christopher Weuve says:

A long submarine mission is six months, and keeping people sane is an issue, solved in part through over-work (which I think helps in the short run) and very careful screening.

Christopher Weuve

A more constructive approach (for officers) is a huge stockpile of study-spools and daily home-work in such topics as higher mathematics, astronavigation, and nuclear physics. Plus other non-space related subjects just to keep the mind flexible. There will also be an active schedule of cross-training, e.g., the astrogator learning how to maintain an atomic drive unit. You never know when knowledge of a job outside of your specialty could prove vital in an emergency.

Once the handful of novels have been read, the drama tapes have been run to death in the display tank, the music tapes have been played to boredom, once the lies have all been told and the card games have faded for lack of a playable deck, Climber people turn to studying their vessels. To what we call cross-rate training, the study of specialties other than their own.

From Passage At Arms by Glen Cook (1985)

It takes over 12,000 hours, nearly 18 months Earth time, and there's not much to do on the way. (ed note: Terra to Asteroid Belt) I kept telling myself it wasn't so bad. I had it easier than those poor blokes on sailing ships ever did. They had storms and scurvy and they were wet all the time. They had the sea, but I had all the stars in the universe, rivers of stars, stars without number, and no atmosphere to get in their way.

But the old sailors tired of the beauties of the sea, and it wasn't long before I was sick of the stars.

We had other compensations. I had my choice of more than a hundred programmed learning courses I could take. Foreign languages, ancient history, higher math for amusement; I got a master's in engineering for professional work; I studied up on mining and manufacturing in space. It was all there, anything I wanted. Information stored in holographic chips doesn't mass very much, and if there was anything else one of us wanted they'd beam out a program from Earth. They even sent ball games and movies.

There was also the work. Nothing on the ship was automated. Any job that a human could do, we did for ourselves. Of course we could get clever and build automatic systems, and we did, but that took up time. The ships are designed that way. Space Industries doesn't want its people going stir crazy on the way out. They have too much money tied up in us. Coming back they wouldn't care...


Then there was privacy. We didn't have much. Each of us had a compartment about the size of a bunk. The partitions were as thin as they could make them. No soundproofing. If we wanted quiet, we wore earphones. Not earplugs — there were times when we needed to hear what was happening and hear it fast. Otherwise we wouldn't live to enjoy the privacy.

From Bind Your Sons to Exile by Jerry Pournelle (1976)

And the sergeant in charge of the enlisted men will have to know when to turn a blind eye to the home-made moonshine "still" hidden on Z deck and the floating poker and dice games. Gambling and rocket-juice will combat boredom. As will other forms of recreation.

In the anime Planetes, they recognize the fact that having male and female crew members cooped up in close quarters for weeks at a time can cause certain tensions. When stocking a spacecraft for a mission, one officially required item is a selection of erotic magazines. This allows the crew members to take care of the problem in solitary fashion.

We fired four of them for being drunk on the job; Tiny had to break one stiff's arm before he would stay fired. What worried us was where did they get it? Turned out a ship fitter had rigged a heatless still, using the vacuum around us. He was making vodka from potatoes swiped from the commissary. I hated to let him go, but he was too smart.

Since we were falling free in a 24-hour circular orbit, with everything weightless and floating, you'd think that shooting craps was impossible. But a radioman named Peters figured a dodge to substitute steel dice and a magnetic field. He also eliminated the element of chance, so we fired him.

From Delilah and the Space-Rigger by Robert Heinlein (1949)

After about a week of one gee, Private Rudkoski (the cook's assistant) had a still, producing some eight liters a day of 95 percent ethyl alcohol. I didn't want to stop him - life was cheerless enough; I didn't mind as long as people showed up for duty sober - but I was damned curious both how he managed to divert the raw materials out of our sealed-tight ecology, and how the people paid for their booze. So I used the chain of command in reverse, asking Alsever to find out. She asked Jarvil, who asked Carreras, who sat down with Orban, the cook. Turned out that Sergeant Orban had set the whole thing up, letting Rudkoski do the dirty work, and was aching to brag about it to a trustworthy person.

If I had ever taken meals with the enlisted men and women, I might have figured out that something odd was going on. But the scheme didn't extend up to officers' country.

Through Rudkoski, Orban had jury rigged a ship-wide economy based on alcohol. It went like this:

Each meal was prepared with one very sugary dessert - jelly, custard or flan - which you were free to eat if you could stand the cloying taste. But if it was still on your tray when you presented it at the recycling window, Rudkoski would give you a ten-cent chit and scrape the sugary stuff into a fermentation vat. He had two twenty-liter vats, one "working" while the other was being filled.

The ten-cent chit was at the bottom of a system that allowed you to buy a half-liter of straight ethyl (with your choice of flavoring) for five dollars. A squad of five people who skipped all of their desserts could buy about a liter a week, enough for a party but not enough to constitute a public health problem.

From The Forever War by Joe Haldeman (1975)

Four riggers showed up at the med module. Rather, two riggers towed two others. Even the two who could move didn't look very well. In spite of weightlessness, they managed to stagger.

"Sweetie, we don't feel so damned good," one told Angela as they entered the module. They rebounded from the edge of the hatch as they did so. "Kin ya give us somethin' to make us feel better? Ol' Jim here—and Al, too—passed out on us. And I'm about to pass out, if I don't heave first."

Angela managed to get a plastic bag to the man before he threw up. But the other conscious man beat her to it.

Fred was the second team member on the scene. He didn't pay any attention to the conscious men, but started checking one of the unconscious ones. "Angela, he's comatose—cyanotic or acidotic. I can't tell without a blood check. Same with the other one."

"They've all been drinking," Angela noted.

"You betcha! Hell of a party!" one of the conscious ones muttered thickly.

"Alcohol poisoning?" Angela ventured to guess.

"Nope," Fred put in. "I'll bet they got a load of orbital moonshine, and what we're seeing are the effects of methanol."

"Dr. Noels!" Angela called out, but Tom was already out of his quarters and into the med module, having been attracted by the commotion. "Possible methyl alcohol poisoning!" she told him as he came up to her.

Tom took one look and acted fast. "Get them down. Angela, Fred, start positive-displacement IVs with sodium bicarbonate on the two who've passed out! Dave, shag it out here stat! You, too, Stan!

"I need blood analysis as fast as you can get it," Tom told his med tech. "Blood-alcohol level, along with pH and electrolyte balance. Accuracy second to speed, because if it's methanol we haven't got much time. Angela, Fred, Stan, we treat for methanol poisoning first! If it's something else, it'll be less serious."

They strapped all four into med module treatment units and started the IVs.

"This guy's going fast," Stan remarked. "Acts like traumatic shock, Doc. Hypotension. BP down to seventy over forty!"

"Gastric lavage!" Tom snapped. "Get it started on the others, too. Whatever is in there, pump it out of them!" He turned to his conscious patient. "Any headache? Leg cramps?"

"Uh . . . naw—but my gut hurts somethin' terrible!" And he passed out.

"What were you drinking?" Tom asked the remaining conscious man. "Tell me fast! It could save your life!"

"Aw, we was just havin' a li'l party with some stuff Al made from raisins and breakfast cereals we took from the cafeteria. Pretty good moonshine, too . . ."

"It could be anything," Stan pointed out.

Tom didn't say a word. He was thinking. He ran through the symptoms of the various alcohol poisonings. He knew he was doing the right thing when it came to wood alcohol ingestion: sodium bicarb IV with gastric lavage. He wouldn't know whether or not to try rebalancing electrolytes until he got the blood work-ups from Dave, who had drawn his samples and was working rapidly in the med lab section of the module.

Dizziness. Discoordination. Gastroenteritis. Hypotension. But no cramps. Obviously no convulsions . . . yet. The unconscious ones were in a stupor with falling blood pressure, but the condition didn't add up to methanol poisoning.

Gastric lavage produced a brownish liquid smelling of alcohol.

"See what Dave can do with it," Tom told Angela.

The initial blood report from the comatose man showed pH in the normal range but various departures from normal in electrolytes. There was also evidence of hypoglycemia.

"All four of them can't be diabetic!" Tom muttered to himself as he looked over the scribbled note from Dave. "They'd never have gotten past the medical check at JSP! What the hell is it? I've never seen this before. Angela, have you?"

"No. Botulism, perhaps?"

"Not from a liquid as loaded with ethanol as their drink was," Tom observed. "Well, this is what I've got GALEN for!"

He pushed off to the med module treatment-bay terminal and got on line. He keyed in the symptoms and requested analysis and most probable diagnosis. The computer worked it over on Earth and shot back the sentence that flashed across the display screen: INCOMPLETE SYMPTOMATIC REPORT. CHECK FOR RETINAL INJURY AND REPORT FINDINGS.

Tom's first peek through the ophthalmoscope into the eyes of the man still semiconscious revealed normal eye grounds. He typed into GALEN: NO RETINAL INJURY. EYE GROUNDS NORMAL.

As quickly as he had finished typing that, the reply appeared: PROBABLE DIAGNOSIS: ISOAMYL ALCOHOL POISONING. SIMILAR TO ISOPROPYL ALCOHOL POISONING. INGESTION OF 8 FL OZ STRAIGHT ISOAMYL ALCOHOL PROBABLY FATAL. OTHERWISE, PROGNOSIS FOR RECOVERY GOOD. TREATMENT: GASTRIC LAVAGE, IV GLUCOSE, CORRECT DEHYDRATION, AND ELECTROLYTE CHANGES. DIALYSIS IF POSSIBLE.

"Isoamyl alcohol. Fusel oil" Tom said, snapping his fingers.

"I know these guys," Fred added. "Hard drinkers. All of them. Probably tried to smuggle hooch up but got caught. And the limited ration that Pratt permits everyone every week wasn't enough for these boozers. So old Al here—he's from Georgia—I'll bet he figured he'd make himself some moonshine instead. Ten to one, they've got a vacuum still rigged somewhere outside a convenient lock."


Oh, don't worry; we saved them. They were full of fusel oil. Why don't you put some bread in the cafeteria so anybody eke who tries this will at least be able to filter it through a loaf of bread first? Bread won't take out all the fusel oil, but it'll probably keep the concentration below the lethal limit."

From Space Doctor by Lee Correy (G. Harry Stine) 1981

...but had warned him against exposing his skin to the Sun. That way he could get a very serious and uncomfortable burn. According to Mercer, the only space-tanned astronauts were the ones who appeared in TV plays. Real spacemen avoided the Sun, and if one of them got burned, it was a mark of sheer carelessness. A good spaceman learned to control himself as well as his ship, Mercer had said, and keep his mind busy and alert. Space was a very beautiful, but a very lonely and dangerous place, if one did not keep control.

From Lifeboat by James White (1972)

Microgravity Hand-to-Hand Combat

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