The space environment is so inconvenient for human beings. There is so much that one has to bring along to keep them alive.
Life Support has to supply each crew member daily with 0.0576 kilograms of air, about 0.98 kilograms of water, and about 2.3 kilograms of (wet) food (less if you are recycling). Some kind of artificial gravity or a medical way to keep the bones and muscles from wasting away. Protection from the deadly radiation from solar storms and the ship's power plant and propulsion system. Protection from the temperature extremes in the space environment. Protection from acceleration. Medical support. And then there are the psychological factors.
Recently John Lumpkin and I were allowed the rare privilege of submitting questions to NASA astronaut Captain Stephen G. Bowen a couple of questions about life in the space environment.
The bottom line seems to be the acceleration should be limited to 4g or less if you want the astronauts capable of using their hands on controls, and limit it to 17g while sitting down or 30g while lying flat to prevent serious injury to the astronauts. But only for less than 10 minutes or so, see graph below for details. This is usually not a problem unless you are dealing with a torchship. Conventional spacecraft cannot accelerate at that rate for much longer than 10 minutes before their propellant tanks run dry.
Note that the piloting controls will need to be specially designed to be used under 4gs, you ain't gonna be able to do fussy fine control when your arms weighs 20 kilograms each.
In the science-fictional role playing game Universe, people with enough money can have an "internal gravity web" surgically implanted. This is a series of strong nets anchored to bone that support the internal organs. It allows the person to undergo accelerations larger than 2.5g indefinitely with no ill effects.
|Transverse forces supine||+Gx||Lying on your back||Eye Balls In||Recommended high acceleration position|
|Transverse forces prone||-Gx||Lying face down||Eye Balls Out||Second-best high acceleration position|
|Positive longitudinal||+Gz||Sitting with head above heart||Eye Balls Up||Third-best high acceleration position|
|Negative longitudinal||-Gz||Standing on your head||Eye Balls Down||Really stupid|
The relative position or orientation of the subject is of prime importance in determining tolerable levels of gravitational or acceleration force, or "g force.' As the g force is gradually increased, certain effects are observed.
Figure 5 shows the time-tolerance relationships for positive longitudinal forces and for transverse forces (either prone or supine, prone being the position of lying face down and supine being the position of lying on one's back).
For the transverse position, human subjects in Germany during World War II were subjected to 17 g's for as long as 4 minutes reportedly with no harmful effects and no loss of consciousness. The curves indicated for very long periods of time are extrapolations and are speculative, since no data are available on long-term effects. Col. John Stapp, Air Force Missile Development Center, has investigated extreme g loadings, up to 45 g's, sustained for fractions of a second; These are the kind of accelerations or decelerations that would be experienced in crash landings. For these brief high g loadings, the rate of change of g exceeds 500 g's per second.
As a matter of interest, the beaded line on the figure indicates the approximate accelerations that would be experienced by a man in a vehicle designed to reach escape velocity with three stages of chemical burning, each stage having a similar load-factor-time pattern. This curve enters the critical region for positive g's. Most individuals would probably black out and some would become unconscious. However, for individuals in the transverse position, this acceleration could be tolerated and the individual would not lose consciousness.
Gross effects of
Effects: g's Weightlessness 0 Earth normal (32.2 feet/second) 1 Hands and feet heavy;
walking and climbing difficult
2 Walking and climbing impossible;
crawling difficult; soft tissues sag
3 Movement only with great effort;
crawling almost impossible
4 Only slight movements of arms
and head possible
Longitudinal g's, short duration
(blood forced from head toward feet):
Effects: g's Visual symptoms appear 2.5 - 7.0 Blackout 3.5 - 8.0 Confusion,
loss of consciousness
4.0 - 8.5 Structural damage,
especially to spine
18 - 23
Transverse g's, short duration
(head and heart at same hydrostatic level):
Effects: g's No visual symptoms or
loss of consciousness
0 - 17 Tolerated 28 - 30 Structural damage may occur > 30 - 45
An acceleration couch is a chair that will hold an astronaut in relative comfort under several gs of acceleration. The Apollo crew's acceleration couches only had to protect the crew from a maximum of 4gs on lift-off, and about 7gs during reentry.
In The Mote in God's Eye by Larry Niven and Jerry Pournelle, the couches had a built-in "relief tube" (i.e., a rudimentary urinal) for use during prolonged periods of multi-g acceleration. For various reasons military crews were all stag, no women allowed.
If you have a torchship, and it is going to accelerate at more than one g for longer than a few minutes, the crew is going to need special couches to lie in. Otherwise the g forces will cause severe injury or even kill. A standard Apollo couch just ain't gonna cut the mustard. You are going to need something more fancy.
The next step up is an advanced waterbeds or flotation mattress. The astronaut lies on a big flexible plastic bag full of water. The water automatically conforms to the contours of the astronaut's body.
In Robert Heinlein's Sky Lift and Double Star these are called called "cider presses" for sarcastic reasons. The water mattress is the fruit and the astronaut is the piston.
In The Mote in God's Eye by Larry Niven and Jerry Pournelle the flotation chairs were supplemented by a few motorized acceleration couches used by damage control parties who had to move around during high gs. Such mobile couches also appeared in Joe Haldeman's The Forever War.
In the real world, liquid breathing is a technique with applications to ultra-deep ocean diving. Past a certain depth the water pressure will crush a diver's lungs into pulp. But since fluid is incompressible, filling the lungs with fluid instead of gasous breathing mix will provide protection. They do not quite have the technique ready for commercial use, yet, but they are working on it. A gentleman named Arnold Lande patented a liquid breathing scuba suit in 2010.
You can see this in the movie The Abyss. The bit with the man is special effect, but the part with the rat is real.
Since multiple gravities of acceleration stress the internal organs much like water pressure, fluid breathing could provide acceleration protection as well.
Foreseeably science fiction has several choice examples of acceleration protection constructed out of pure handwavium. They are amusing but I wouldn't take any of them seriously.
Common scifi names include acceleration compensator, deceleration compensator, inertial compensator, deceleration equalizer, and drive compensator. Sometimes scifi misuses the term "inertial damper" which has a very different and very mundane meaning, the proper term is Inertial Negation.
David Gerrolds notes that the inertial dampers in Star Trek TOS would render impossible all those scenes where the valiant bridge crew of the starship Enterprise get jolted out of their seats. They would not be affected any more than shaking a piece of amber containing fossilized insects would jolt the bugs.
In addition to the drives mentioned here, there is also the broad classs of carrot-on-a-stick drives. These avoid killing the crew by high acceleration by virtue of using handwavium paragravity for acceleration. Since gravity (or paragravity) accelerates all the atoms of of both the ship and crew evenly, the crew will be in free fall regardless of how massive the acceleration is.
Anders Sandberg has an impressive scientific survey of theoretical techniques on his blog here
With the exception of Charles Sheffield's "Balanced Drive." It is more unobtanium, we can't build the blasted thing but it does not break any of the laws of physics (it is really really hard to make a disk one hundred meters in diameter and one meter thick with the mass of Mount Everest). It sure looks like a handwavium carrot-on-a-stick drive, but it isn't.
Handwavium acceleration protection includes:
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.
In Doppelgänger the astronauts spent the three week trip plugged into a "Heart Lung Kidney" machine via veins in their wrists. This kept them oxygenated, fed, and sedated into a deep sleep for the entire trip.
In William Tedford's Silent Galaxy, 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.
SpaceWorks Engineering is working on a cold-sleep system for a NASA mission to Mars. You can read their report here. This is for a cold-sleep/hibernation system, since we are no where near knowing how to do full suspended animation.
Having the astronauts pass the journey in cold-sleep has many benefits, but the most remarkable one is the huge payload mass savings. In the table below, the habitat module from the NASA Mars Design Reference Architecture (DRA) 5.0 study is compared to the same module using cold-sleep technology. The mass savings is a whopping 52% !
|TOTAL MASS IN LEO||41,330||19,860||-52%|
The report lists the following benefits:
- Reduction in required amount of consumables
- Reduction in required pressurized living space volume
- Elimination of many ancillary crew accommodations (galley, kitchen, exercise equipment, entertainment, etc.)
- Reduction of psychological challenges for crew
And the Hab Module mass savings can be used to increase payload, increase delta V, expand launch windows and mission options, increase radiation shielding, reduce the number of heavy-lift launches, reduce number of on-orbit assembly operations, increase subsystem mass margins (to improve redundancy, reliability, and safety).
The report focuses on Therapeutic Hypothermia (temperature-based hibernation) as the method of choice to induce cold-sleep. Mostly because it has actually been used medically to treat ailments such as cardiac arrest, ischemic stroke, traumatic brain injury, etc. Chemical/Drug-based (hydrogen sulfide or activating adenosine receptors) and Brain Synaptic-based hibernation are much less mature technologies. The report assumes that therapeutic hypothermia can be advanced to the point where the astronaut's metabolism can be reduced from normal to somewhere between moderate and significant reduction (but not to actual total metabolic stoppage), for periods of many months. Black bears and some rodents can do it, so we know it is possible.
- Invasive: cooled intravenous fluids, e.g., CoolGard 3000Rtm with IcyT catheter by ZOLL Medical
- Non-invasive: evaporative gases in the nasal and oral cavity, e.g., RhinoChill Systemtm
- Passive: conductive cooling (and rewarming) with gel pads placed on the body, e.g., KOALA Systemtm
All three methods are low mass, low power, and easily automated.
The astronauts will be fed by Total Parenteral Nutrition (TPN), which means fed intravenously. The nutrient fluid is a mixture containing lipids, amino acids, dextrose, electrolytes, vitamins, and trace elements; all the essential nutrients needed for a human body to function.
- Delivered via a tunneled central venous catheter or a peripherally inserted central catheter (PICC)
- Administered through pump or gravity IV, usually given at around 50 ml per hour with supplemental maintenance fluids.
- Bypasses the usual process of eating and digestion; digestive tract is inactive.
There are some medical challenges to solve, such as blood clotting, bleeding, infection, electrolyte imbalances, fatty liver, liver failure, bone demineralization, hypo/hyper glycemia, bile stasis, and others. The chosen method must have little or no long-term effects, no effects on crew functional abilities, and there should be some protocol for an accelerated warming/wakeup in case of emergencies
There are some maladies that afflict people who spend prolonged periods in microgravity, exposed to space radiation, and exposed to radiation from nuclear propulsion. These could be characteristic signs of space traveling old-timers.
Maladies from Microgravity
The most obvious effect of microgravity is the astronaut's muscles atrophy and the shedding of calcium by their bones (1% to 1.5% per month, like osteoporosis). Being weak with brittle bones isn't lethal but presumably the astronauts at some point want to return home to Terra and still be able to walk. Science fiction literature is full of mandatory exercise to combat this, with "exercise credits" awarded for time spent under acceleration and in centrifuges. NASA astronauts on the International Space Station have to exercise two hours a day for this reason. Some astronauts (or colonists of low gravity planets and moons) might require man-amplifier prosthetics in order to walk under a full Terran gravity.
Naturally such space osteoporosis can lead to kidney stones, the agony of which is the closest a male will ever come to the sensation of giving birth. Space osteoporosis can also be combated by exercise.
Astronaut's eyes are especially vulnerable. Recently NASA made the horrible discovery that exposure to microgravity for six months or longer causes permanent damage to the eyes, similar to idiopathic intercranial hypertension. There is some evidence that this is due to enzyme polymorphisms that increases astronaut vulnerability to bodily fluid shift in free fall.
Astronauts may appear to be older than they actually are, because microgravity accelerates aging.
And a science fictional favorite is the microgravity adapted astronaut who when on Terra has a tendency to let go of glasses of water in mid air, expecting them to float.
Maladies from Radiation
The two main effects of radiation on an astronaut are  cancer and  death by radiation sickness. You are unlikely to encounter an old astronaut suffering from  unless you like to visit graveyards. But the probability is high that most old astronauts will have undergone treatment for cancer at one time or another. Probably several times. NASA tries to avoid this by ensuring that there are no old astronauts. NASA has strict career limits on astronaut radiation exposure.
Secondary effects of radiation are skin ulceration and blindness due to cataracts scarring. High-mass, high-charged (HZE) cosmic rays might accelerate the development of Alzheimer's disease. Radiation also lowers the immune system (chromosomal aberrations in lymphocytes), but it can recover.
Atomic rocketeers on board an atomic rocket will also without fail have a package of potassium iodide tablets on their persons at all times. Why? If the reactor core is breached, the mildly radioactive fuel and the intensely radioactive fission fragments will be released into the atmosphere. While none of the fission fragment elements are particularly healthy, Iodine-131 is particularly nasty. This is because ones thyroid gland does its level best to soak up iodine, radioactive or not. Thyroid cancer or a hoarse voice from thyroid surgery might be common among atomic rocket old-timers. The tablets prevent this by filling up the thyroid first, before the Iodine-131 arrives. The instant the reactor breach alarm sounds, whip out your potassium iodide tablets and swallow one.
Miscellaneous other Maladies
Astronauts who eat more than fifty grams per day of spirulina algae from your closed ecological life support system run the risk of developing gout. That could be Old Poor Astronaut Syndrome.
Old astronauts might have deformed fingernails due to space suit gloves.
Old astronauts might tend to become alarmed when they feel a breeze. To an astronaut, moving air means you have a hull breech.
Old astronauts might dislike hissing noises. To an astronaut, such noises means your spacesuit has sprung a leak.
Old astronauts might be anal-retentive about having every object either in its holder or tied down. In a spacecraft, unexpected acceleration converts any free-floating object into a deadly missile.
Old astronauts might tend to become alarmed of the building or vehicle they are in shudders. Because spacecraft never shudder unless they are lifting off from a planet's surface or about to disintegrate into fragments.
In Larry Niven's "Known Space" series, belters do NOT perform any hand gestures at all. This is because Niven's belters fly in very small spacecraft called "singleships". The habitat module is only slightly larger than a coffin. Which is also the control cabin, i.e., there are controls on almost every surface.
Space Adaptation Syndrome aka "drop sickness" is a kind of motion sickness caused by weightlessness. Outer space sea-sickness, so to speak. Symptoms include dizziness, fatigue, nausea, vomiting, and an inability to care about anything but your own private world of pain. The joke is drop sickness makes you feel like you are going to die, and you are actually looking forwards to it.
About half of new astronauts suffer from drop-sickness when they first travel into space. Of those who suffer, 50% have mild symptoms, 40% have medium, and 10% have severe. The most severe that NASA ever recorded was that of Senator Jake Garn in 1985. They jokingly use the "Garn scale", where 1.0 Garn is the worst.
Drop sickness usually goes away after two to four days exposure to free fall. Occasionally there is a relapse, which can happen at any time. When suffering from drop sickness, be careful not to rapidly turn or shake your head. This will make the fluid in the inner ear slosh and make things much worse.
Novice NASA astronauts do not take motion-sickness medication on their first trip into orbit. It is considered better for them to be miserable for a day or two but actually adapt to become immune. This is also the reason NASA never schedules EVAs for the first two days of a mission.
Having said that, NASA astronaut always put on a transdermal dimenhydrinate anti-nausea patch when suiting up in a space suit, because throwing up inside a suit can be fatal. A little dramamine is much better than suffocating to death in a vomit-filled helmet.
Drop sickness can be avoided if the spacecraft or station has artificial gravity, though that creates more problems.
In a couple of Robert Heinlein novels free-fall newbies are issued "sick-kits." These are cloth barf bags that strap over your mouth. In other novels spacecraft with large numbers of passengers are equipped with vomit vacuums that stewards use to suck blobs of vomitus out of the air before they splash on something or somebody.
In some old science fiction novels the writers like to pull that tired old joke. The protagonist is offered an anti-drop-sickness pill before lift-off, and they decide to be all macho and decline the pill. Which results in projectile vomiting hilarity. Except in Arthur C. Clarke's Islands in the Sky, the port officials make quite sure that the young protagonist takes all his pills.
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").
It can be even worse if the tin can is a little too cramped.
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.
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.
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. Fornication among the crew is generally aways a bad idea. There will be all the problems common to office romances, with the hatred turned up to 11 by stress of living in such confined quarters.
Last but not least is locally hosted internet games (local because a latency of 24 minutes makes real-time games impossible). However, such games might be restricted to cooperative games. Competitive games are too vulnerable to Griefers. If you have a bunch of crew whose nerves are already on edge due to living in a sardine can for the last eight months, the last thing you want is some sociopath deliberately enraging everybody. Tempers will flare while blood and body parts accumulate on the air intakes.
The other danger is internet games that are a little too immersive. Given the the choice between the real world of sensory deprivation inside the spacecraft and the fantasy world full of adventure and excitement, the crew might lose touch with reality. This was the topic of Poul Anderson's The Saturn Game.
In Anne McCaffrey's novel Dragonsdawn it states that the first two things human colonists always do on a new world are:
Here on Terra coffee is one of the most popular drinks in the world, and there are many who cannot fully wake up and do work until they've had their morning cup of java. Particularly the various branches of the military. There are many who say that the US Navy runs on coffee. Furthermore it is hard to exaggerate the effect coffee houses had on merchant trading and shipping. Ship-owners, merchants, and insurance houses made deals in the coffee houses over cups of "the new black liquor from Turkey".
In a science fictional future, spacecraft crew may be forbidden tobacco to avoid death by asphyxiation but you can bet your last rocket they will have some sort of caffeinated beverage.
But since science fiction authors can't resit using the old Call a Rabbit a "Smeerp" trick, they will have all sorts of strange names for coffee in a desperate attempt to convince the reader that they are not in Kansas anymore. Occasionally in science fiction you will find species of deadly hyper-coffee with extreme effects.
In The Beast Master they drink Swankee, King David's Spaceship has Chickeest, the Sten novels have Caff, Warhammer 40K has Recaff, the Wheel of Time novels have Kaf, The Pern novels have Klah, and the Helmsman saga has Cvcesse. In Derelict for Trade they have Jakek which is a syntho coffee substitute the crew makes do with when times are lean.
More realistically the previously mentioned human colonists will find that coffee refuses to grow on their new world so they will frantically have to find a replacement. Authors are fond of having new colonists complain about how disgusting the local ersatz coffee is and how they miss the real stuff. Second and subsequent generations of colonists have never tasted honest-to-Joe coffee so they are satisfied with the substitute as long as it has plenty of caffeine.
While most illegal drugs and other controlled substances are rather difficult to manufacture in the space environment, good old alcohol is relatively easy. After all, convicts manage to make Pruno in prison; even with limited access to raw materials, workspace, and privacy from prison guards.
In most cases, the actual production of alcohol from sugar is done by yeast cultures. These cultures are almost impossible for the authorities to keep out of the hands of illegal brewer-masters of contraband alcoholic beverages. In the case of making wine, the yeast can be conveniently found already living on the grape skins.
And if the CELSS is using yeast to make single-cell protein, there is no way to prevent moonshiners from obtaining a supply. In 2015 the Australian government was considering making the national staple food Vegemite a controlled substance (inspiring howls of outrage). Apparently home-brewers in remote areas were purchasing Vegemite in bulk and using it to make moonshine. After all, the main ingredient of Vegemite is leftover brewers' yeast extract (not baker's yeast, brewers' yeast). In Australia there has already been a ban on Vegemite in prisons since the 1990's for the same reason. Controlling it outside of prison is going to be an uphill battle.
Needless to say, becoming drunk in an inherently dangerous environment such as deep space is a quick way to get yourself killed. In the US the legal drunk driving limit is 0.08% Blood Alcohol Content (other nations have different standards). A rule of thumb is that one standardized "drink" = one hour = no exceptions (that is, if you had three drinks, wait three hours before driving). For private airplane pilots, the rule of thumb is Eight Hours Bottle To Throttle.
In the U.S. (wet) Navy, drinking alcohol is not allowed while aboard a ship (since the passage of General Order No. 99 in 1914), and off ship it is forbidden if the person is on duty or under-aged. In the U.K., which has a tradition of a daily rum-ration for sailors, crew is limited to consume no more than 35mg of alcohol per 100ml when they are on safety-critical duty (same as the U.K. drink-drive limit). For U.K. naval crew handling weapons the limit is 9mg per 100ml. The U.K. Armed Forces Act of 2011 prohibited the consumption of more than five units of alcohol 24 hours before duty and no alcohol was to be consumed in the 10 hours before duty.
In Jerry Pournelle's Falkenberg's Legion series of science fiction novels the CoDominium navy and marines have no regulations against drinking alcohol, even on duty. But there are severe penalties for rendering oneself unfit for duty (penalties up to execution by firing squad). When deployed, CoDominium marines were commonly given a daily wine ration of half a liter per person.
A "wine" is an alcoholic beverage produced by yeast converting the sugar in fruit juice into ethanol. At some point the ethanol level rises high enough to kill off the yeast, halting production. This limits the proof of wines, usually 9%–16% alcohol by volume (ABV) or 18—32 proof.
A fortified wine is a wine with the alcohol content increased by adding some distilled spirits (generally brandy, which is distilled wine). If the brandy is added before the wine fermentation is completed the resulting fortified wine will be sweet. This is because the brandy kills off the yeast before all the sugar is consumed. Fortified wines can be up to 20% ABV (40 proof).
Some anthropologists have a theory that wine was discovered by some cave-man who took a drink out of a puddle full of rotting fruit.
A "beer" is an alcoholic beverage produced from grain, usually barley or wheat. First the grain is "malted": germinated in hot water, then dried. The malting process creates enzymes which can convert starch into sugar.
The malt is mixed with hot water to create what brewers call "wort" but we can call "yeast food." This allows the enzymes to convert the starch in the grains (which yeast cannot eat) into sugar (which yeast will merrily convert into alcohol). See "saccharification of starch".
After about two hours the malt enzymes has converted most of the starch into sugar, and the wort is boiled to get rid of some of the water. After the wort is cooled, it is put in a fermenter along with hungry yeast. The yeast put on their bibs, whip out their knives and forks, and start gobbling sugar while excreting ethanol. Beer is generally 2%—12% ABV (4—24 proof).
Note that when traveling, if the bacterial content of the local water is questionable, it is much safer to drink the local beer instead of the water. Use beer to brush your teeth as well. An ancient Egyptian tomb inscription boasted about the dear departed's generosity by saying "I gave bread to the hungry and beer to the thirsty".
Some anthropologists have a theory that early man invented agriculture not to increase the supply of food, but to increase the supply of beer.
Since people have a tendency to be min-maxers, they looked for ways to increase the ethanol levels in their product. The tried and true method is to use a distillery rig, aka a moonshine "still". Such items have to heat up the source alcoholic beverage using fire, but in space the abundantly available vacuum can be used instead.
John Reiher notes that you do NOT want to use a vacuum still on beer or any other mash containing hops. One of the essential hop oils, Myrcene, has a boiling point of 63.9° C, which is under alcohol's 74° C. If you're not careful, you'll end up with very hoppy ethyl alcohol (i.e., incredibly bitter).
The basic idea is to remove water from the booze, thus increasing the relative percentage of alcohol. Conventional stills take advantage of the fact that water and alcohol have different volatility. That is, ethyl alcohol boils at a much lower temperature than water.
You boil the wine or mash at a temperature (78°C) which vaporizes the alcohol but very little of the water. Then you send the alcohol vapor through a condenser to turn it back into liquid. The alcohol drips out of the condenser into a jug. The condenser is that copper spiral tube (the "worm") you see on classic moonshine stills. Copper is used because it absorbs sulfur-based compounds which would otherwise make the product taste like skunk juice.
The products of a still are called distilled beverage, spirit, liquor, or hard liquor. Typical distilled spirits are about 40% ABV (80 proof), extreme stuff is 75% ABV (150 proof), Everclear grain alcohol is about 95% ABV (190 proof) which is close to being rocket fuel.
Whiskey and the like are made with pot stills where there is lots of water in the vapor sent to the condenser. After two distillations whiskey has a 70% ABV. Moonshine is made in moonshine stills, with very little water in the vapor. It has a 95% ABV, almost suitable for use in a Rocketdyne RS-88 rocket engine.
There are many kinds of distilled spirits. A "brandy" is distilled wine. A "whisky" is distilled from grain mash (like beer's barley or wheat) except whisky can also be made from corn or rye. You can think of whisky as distilled beer without being utterly wrong. A "vodka" is generally distilled from fermented potato mash, its main feature is the almost total lack of flavorings.
A more low-tech way to increase the alcohol level is to use freeze-distillation (aka "jacking"), such as in the manufacture of applejack. Alcohol freezes at a lower temperature than water (this is why you can use it as antifreeze). So in the American colonial period, apple juice from the harvest was allowed to ferment into a sort of fruit beer (less than 10% ABV). Then during the winter, the juice was placed outside to freeze, or at least the water would. The frozen lumps of water were removed, thus raising the alcoholic content of the remainder (up to 40% ABV). This method might be popular on newly colonized Terran planets with a low tech base. A drawback to freeze-distillation is that (unlike conventional distillation) the process concentrates dangerous poisons such as methanol and fusel oil.
Back in the 1920's during Prohibition in the US, amateurs made Bathtub gin. This lead to the creation of many gin cocktails, as the speakeasies desperately experimented with sugary flavors to mask the vile taste of the poorly made gin. Everything old is new again. Enlisted spacecraft crew will also be eager to steal fruit juices from the quartermaster to doctor the foul product of their vacuum stills.
Alcohol is absorbed into the blood stream slowly in the stomach, but the rate can be increased if the beverage is carbonated. This is why strong people who are apparently unaffected by a shot of whisky will sometimes start to giggle if they drink bubbly champagne (carbonated wine). Beer is carbonated, but it is so weak it needs all the help it can get. Champagne has more of a kick than non-carbonated wine. And a cocktail that includes some sort of carbonated mixer is most potent of all.
Some old SF novels call space hooch "rocket juice", as a tribute to the torpedo juice from WW2. In Star Trek, Captain Kirk liked his Saurian Brandy, and McCoy was fond of Romulan ale. And of course Scotty is partial to scotch, even mixed with theragen.
It is also possible to have an alcoholic beverage as the focus of a science fiction story. I highly recommend Golubash, or Wine-Blood-War-Elegy by Catherynne M. Valente
Obviously there are problems with confining too many astronauts in a too-small habitat module for prolonged periods of time with not enough sleep and practically no privacy. Add pressure from ground control to work the astronauts to death coupled with boredom and you have a real recipe for blood floating all over the module. At least in an Arctic research station a researcher close to snapping can step outside for a breath of fresh air. Not so the astronaut
Cosmonaut Valery Ryumin, twice Hero of the Soviet Union, quotes this passage from The Handbook of Hymen by O. Henry in his autobiographical book about the Salyut 6 mission: “If you want to instigate the art of manslaughter just shut two men up in a eighteen by twenty-foot cabin for a month. Human nature won't stand it.”
This was sort of hinted at by the 1999-2000 Russian Sphinx-99 experiment. This enclosed six crewmembers in a simulated space station for six months. About two months into the experiment there was a bloody fist-fight between two of the Russian crewmembers. Shortly thereafter the Canadian female crewmember (Dr. Judith Lapierre) was dragged off camera by the Russian commander and forcibly french-kissed despite her vigorous protests. In two separate incidents.
And then there is the Break-Off effect. This was first reported before the dawn of space travel, by high altitude military airplane pilots. It was a type of psychological dissociative anomaly, a feeling of detachment. Most pilots felt peaceful, a few euphoric, and about a third were panic-stricken.
It was thought this would also happen with astronauts. But in the 1970's when cosmonauts and astronauts actually started flying the problem seemed to disappear.
It wasn't until recently that it became clear the Break-Off effect did not disappear in astronauts. What disappeared was the astronauts reporting it. Astronauts are in constant terror of being grounded, so they developed a "lie to fly" culture. The last thing they are going to do is report to the flight surgeons some scary mental breakdown that will get them grounded faster than a teenage girl staying out five hours past her curfew.
During the Apollo missions, some astronauts reported how the vision of Earth as the big blue marble caused a sudden cognitive shift in awareness. They suddenly saw Earth as a fragile ball of life where national boundaries became unimportant. A writer named Frank White coined the term The Overview Effect, and wrote a popular book on the topic in 1987. You can find some quotes about the effect here.
And there are some psychologists who suspect that the Break-Off Effect and the Overview Effect are one and the same.
Terry Pratchett's Discworld novels are satirical fantasy for thinking people. While they are comedy, many of the jokes require a bit of scientific knowledge on the part of the reader. Which explains why I find them so entertaining. My personal favorites are The Truth (the invention of the newspaper), Going Postal (post office vs the Victorian internet), and Raising Steam (the invention of the steam locomotive).
Anyway like many fantasy novels the Discworld has a race of dwarfs. They spend most of their time in cramped mines in very close quarters with other dwarfs. Things can get tense.
Much like spacers on a prolonged deep-space mission in a tiny hab module, actually. Or asteroid miners.
As a sort of social network to reduce tensions Discworld dwarves use something called "mine signs", a species of graffiti. I am wondering of the idea can be adapted to a rocketpunk universe. Imagine Banksy using Spacers Runic
On a spacecraft it might be considered a bit ghetto-like to spray-paint Dwarf Mine Signs on the corridor walls to blow off emotional steam, even if you are using Spacer's Runic. Especially if this is a military spacecraft.
A more sophisticated method to deal with crew getting cabin fever would be to use a shipboard version of social media (space twitter) sending hashtags as a reflexive meta-commentary ( #THEFOODSTINKS! ). The main thing is that the messages have to be sent anonymously. Just like graffiti.
There was something like that in Sir Arthur C. Clarke's novel The Songs of Distant Earth, called "Shipnet."
A NASA technician said "If you treat vacuum as you would poison gas you won't go far wrong."
How does space kill you? Let me count the ways. Face it, the human body was not designed to properly function in the vacuum of space. At a rough guess a person can survive space exposure as long as they are placed back inside a pressured atmosphere within 90 seconds. After that time, death might be unavoidable. You will only have about ten seconds before you become unconscious. Dr. Geoffrey Landis has an analysis here. There are some more links on the topic of explosive decompression here.
And anybody who's seen 2001 A Space Odyssey knows that a human exposed to vacuum is not going to pop like a balloon.
In order of lethality the effects are:
If you take glass of water, and lower the air pressure, the temperature point at which the water boils is lowered as well. This is why cake mixes have high altitude instructions: the watery part has a lower boiling point/maximum temperature than normal so it takes longer to cook. If you are living in a habitat module with a pure oxygen breathing mix, the pressure will be at about 32.4 kPa (80% normal Terran atmospheric pressure). Here too the cake mixes will take longer to cook since water boils at 70° C, and your tea will always be lukewarm.
What I am leading up to is the Armstrong Limit. You see, if the pressure drops to 6.3 kPa, water will boil at 37° C. Which just happens to be normal human body temperature. The saliva will boil off your tongue, the tears will boil off your eyes. If you become so frightened that you pee in your pants, that will boil as well. The same goes for poop but that's a horrible image I just don't want to think about.
The blood will boil in your veins too, were it not for the fortunate fact that your skin will pressurize your vascular system enough to prevent that unhappy state of affairs. This is why soft suits can get away with not pressurizing your body.
Naturally astronauts will not commonly be constantly exposed to 6.3 kPa. Much more likly they will briefly encounter it as the pressure plummets to zero kPa, as all the breathing mix goes rushing out a deadly tear in their space suit or a major breech in the hull of the habitat module.
But in any event if your saliva starts to boil, be aware that you have only ten seconds to get to safety before you lose consiousness, and 80 additional seconds for your buddies to drag you into somewhere pressurized before you die. Be quick or be dead.
In addition: hands, feet, arms, and legs that are no pressurized will suffer an attack of Kittinger Syndrome. They will swell up to about twice normal size, with accompanying agonizing pain. Bringing back pressure will return them to normal, but if swollen for more than a few minutes there wil be aneurisms and hematomas.
Arguably the biggest killer in the space environment is Stupidity.
Larry Niven coined the phrase "Think of it as evolution in action".