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.

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.

A cursory web search on "Spirulina" will reveal how popular the stuff is in health food circles.

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)

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)

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

Air

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!...

..."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.

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.

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.

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.

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.

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.

Surviving Vacuum

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

And anybody who's seen 2001 A Space Odyssey knows that a human exposed to vacuum isn't going to pop like a balloon. Dr. Geoffrey Landis has an analysis here. Executive Summary: You would survive about a ninety seconds, you wouldn't explode, you would remain conscious for about ten seconds. So in an emergency a crew member can join the Vacuum Breather's Club, just like David Bowman. But be careful of sunburn. There are some more links on the topic of explosive decompression here

"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)

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

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

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 I was 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.

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)

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)

...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

As a final note, Joshua Whalen is of the opinion that when it comes to microgravity hand-to-hand combat, punching your opponent is worse than useless. However, techniques derived from JuJitsu or Tai Chi/Pa Qua will work. Fisticuffs fall afoul of Newton's third law, but an elbow breaking arm lock or a choke hold still works just fine. You might want to do some research on the hand-to-hand combat techniques used by Navy Seals when both they and their opponent are underwater in SCUBA gear.

And obviously cutting your opponent's air hose works just as well in space as it does underwater.