Life in Space
Plenty of books have been written about living in space, but they tend to concentrate on the past experience of people who have stayed in orbit. These people have nearly all been in the unusual situation of doing scientific research. And they have all undergone extensive selection and training, because going to orbit is so expensive today that it would be very wasteful if they were ill or failed to do some of their planned work. And so they've mostly been very busy all the time. So most books don't say much about how it will be for people to live in space for fun, for example in an orbiting hotel.
Some astronauts have complained about being in zero G because it makes their work difficult. Objects like screwdrivers and screws don't stay still but float around. You can't use your body's weight to hold things down - you have to brace yourself against something rigid, and so on. It would be easier to do their experiments on the ground.
Short stays
But most of us will be staying in space for a holiday, not working, and for that zero G is fun. Even the most ordinary activities like eating and drinking, having a bath, moving around your room or along a corridor, undressing and getting into bed (with or without a partner) all become new and entertaining in zero G. Children are sure to love it! And once sports facilities are available, a whole new range of activities will be possible.
Living in space for longer periods like a few months or permanently, is more complex, as you have to take precautions against the long-term effects of zero-G and cosmic rays. Living in space for just a few days as a tourist you won't have to worry about most of this.
The fact is that anyone can live in space for a few weeks without any problems, without any ill effects, and in doing so they will have endless opportunity to enjoy the pleasures of zero G.
Keeping fit
Hotel staff will stay in orbit for longer periods of a couple of months at a time, and they'll have to follow a number of health rules. First they'll have to exercise regularly, particularly their leg muscles, because in zero-G without the usual weight acting on them, leg-bones get thinner. This is done with a variety of equipment, such as "exercise-trousers" which have strong elastic between the ankles and the waist which the leg muscles have to stretch, and which puts pressure on the bones and joints.
Radiation
Second, hotel staff will be above the atmosphere which filters a lot of the radiation coming in from space. So orbital hotel staff will be like staff at nuclear power stations, research centers which use radioactive materials, astronauts and other professions: they'll receive higher radiation doses than the general population, which will be closely monitored. As in these other professions, the additional risks will be very small, and staff will receive close health monitoring to prevent any problems arising. Like professional "radiation workers" on Earth, they'll generally be people who don't intend to have more children, since reproduction is particularly sensitive to disruption by radiation.
No barrier to working in space
Of course hotels are going to need a lot of staff. It's easy to see: as tourism reaches a rate of hundreds of thousands of guests per year, most of whom will stay in orbit for a few days, the number of guests in orbit simultaneously will reach thousands - presumably divided between a number of hotels run by competing companies. And since a high ratio of hotel staff will be needed to provide top quality service, there are going to be thousands of professional hotel staff who do an occasional tour of duty in orbit. But even given the extra health risks, I don't think there'll be any shortage of applicants for the job! In fact it's likely to be a popular posting! And it will probably be a long time before any other sort of work employs more people in orbit than hotels. Rather different from the usual image of the future of space activities, but business does what makes money!
Health and Fitness
Lots of people think you need to be a superman to survive the trip to orbit, or to live there. But it's not true. This is just a myth - largely based on fictional stories and movies from before the first space flight was made. (Remember Tintin and friends blacking out? Or the strained expressions on people's faces in old space movies?) The fact is that acceleration of even several Gs is no problem at all so long as you're lying on your back. It doesn't hurt. It's not even hard to breathe. It's like having a baby lying on your chest. But it's not uncomfortable so long as you're lying on something soft. And there's no need for an individually contoured couch!
If you insist on standing or sitting upright, the blood in your head would try to fall towards your feet, and if you didn't take counter-measures you'd probably black out around 5 G, due to falling blood pressure in your head reducing the oxygen supply to your brain. Lying down solves this problem. The only minor inconvenience is that if you want to lift your arms they're very heavy.
The main reason why astronauts and cosmonauts go through such exhaustive selection and training is because their flights are very expensive. And so if a problem arose, like they got appendicitis, and the mission had to be abandoned, this would be a terrible waste of (taxpayers') money. The early astronauts were test pilots, because no-one knew what they were going to experience, and they were flying in dangerous vehicles. But today, essentially anyone who's in reasonable health could go and stay in orbit - if there was an economical launch vehicle available. Certainly anyone who would fly in an aeroplane or ride on a roller coaster will have no problem.
That isn't to say there aren't a number of health "issues". We needn't call them "problems" any more because we know the answers - at least enough to allow us to operate a safe space tourism business. These two issues are "space sickness" and the long-term effects of living in space.
Space sickness
Although staying in space for a short time is quite safe, it's well known that many people who visit space, on the US space shuttle or the Russian "Soyuz" launcher, feel sick, and even vomit. The reason for this is much the same as the reason why some people are sick in cars or ships - "motion sickness" or "travel sickness". (For those who are interested in the details, it's due to the conflict between what your eyes are telling your brain and what your inner ear is telling your brain about your bodily position. Inside a ship your eyes tell you you're not moving, but your inner ears tell you you are. That's why going out on deck helps - your eyes can see you are moving.)
For a long time it was said that "space sickness" is somehow special, and different from other forms of travel sickness. But it isn't. Sure, the precise type of movement of the inner ear is a little different in zero G - just as car-sickness, sea-sickness and air-sickness are a little different from each other. But the good thing is that normal travel sickness medicines are entirely effective against "space sickness", as they are against other forms of motion sickness.
The main reason people are sick on the space shuttle is that they are asked not to take anti-sickness medication, so that NASA staff can do research on the phenomenon! It is indeed possible to do "research" on space sickness - just as it would be possible to do research on sea sickness. But there's no need to. Brain scientists don't fully "understand" sea-sickness - but the cruise industry doesn't pay them to do research. They just make it easy for passengers to get hold of effective medication! The commercial approach - low cost and effective. The same will be done for space tourism, and no-one will need to be sick. Unfortunately, most journalists still don't know this, and trot out the same old line "It's a pity that everyone's going to be sick, so it'll never get very popular..."
Bird legs and blocked noses
One phenomenon - it can't really be called a problem - is the fact that in zero gravity, as the fluids in your body are no longer pulled down towards your feet by gravity, it tends to accumulate higher up in your body, creating what some people call "bird legs" - the muscles of your legs appear smaller than on Earth - and also "fat-face" (or perhaps more appropriately "Moon-face"). Your family and friends will look a bit different in zero G! (You can see this in photos of astronauts.)
There's a serious side to it which is that this also gives you a slight feeling of nasal congestion which may be uncomfortable for some people. So using decongestants may be popular. In addition, having a head cold may be more unpleasant than on Earth - so medication to suppress the symptoms (now common on Earth) may be desirable.
Unfortunately astronauts and cosmonauts don't go to space if they have a cold - so we don't have good information on this! This is an example of how the experiments desirable for space tourism are different from the experiments that space agencies do aimed at long term space flight, etc. As they get wise, maybe you'll see an advertisement saying "Astronauts wanted - must have streaming cold".
Long term health effects of living in space
On Earth your muscles and bones are continually subject to gravity. This exerts forces on them, generally putting the muscles in tension and the bones in compression. When you're floating in zero-G most of these forces disappear, and your muscles are very relaxed. (One result of this is that people living in orbit don't get very tired, and tend to sleep less than down here - 3 - 4 hours is said to be common.) This condition is no problem for a week or so, but if it continues for months, the muscles start to shrink through lack of use. (When you train a lot, your muscles grow in volume; when you don't use them they shrink!) This includes the muscles of the heart, because pumping blood in zero G is much easier than in 1 G. So astronauts and cosmonauts staying in orbit for months make time for daily physical exercise to keep their muscle strength up so that they won't be weak when they get back to Earth.
Another effect of living in weightlessness is that, like your muscles, your bones also lose mass. Though bones seem pretty solid, they're alive, and like many biological systems they're in equilibrium between building themselves up and breaking themselves down. So they continually take calcium from the blood and release calcium into the blood. But when the stresses on the bones fall, as when you're floating around in zero G, less calcium is taken up from the blood because the cells sense less need for it. For a week or so this is no problem. But if it continued for months, your bones would get significantly weaker. So people who spend long periods in space have to use special trousers with strong elastic joining the belt to the ankles, which puts compressive forces on the leg bones and joints, and convinces them to take up more calcium. It may not be so elegant, but by doing this they don't lose so much bone mass. Further research will probably develop even better remedies. But we have to select priorities. It's much more urgent to get launch costs down - by developing a space tourism industry, among other things - than to do this research soon. Current knowledge is quite adequate for building a medically safe orbital tourism industry - and after that it will be much cheaper to do this research. That would be much better than continuing to spend hundreds of $millions to perfect this treatment when there's no urgent need for it.
Space radiation
Nuclear radiation, including both high-energy particles such as protons and other atomic nuclei, and high-frequency electro-magnetic waves, X-rays and Gamma-rays, can damage biological cells by ionizing molecules inside them. Most of the time this damage is simply repaired automatically. But if a lot of radiation is absorbed, the damage can overcome the body's ability to repair it, and the damaged cells may die or may become cancerous (that is, growing uncontrollably).
In space, all of these types of radiation are present to some extent - protons and electrons trapped in the Earth's radiation belts and coming from the Sun, and energetic particles coming from further away ("cosmic radiation"). The Earth's atmosphere protects us from them to a large extent (but not completely; people living at high altitude receive considerably higher "background radiation" doses than those living lower down!) Roughly speaking, the longer you stay in space, and the higher the orbit you travel in, the more radiation you absorb, and so the higher the chance of damage. In most cases, spending a few days in orbit will pose no risk at all. The radiation absorbed will be equivalent to the average radiation you receive in a year on Earth (from X-rays, background radiation, and environmental pollution). There are long-established international standards for the recommended maximum radiation doses both for the general public, and for "radiation workers" - people working in hospitals who use nuclear materials, in the military, in nuclear power stations, and astronauts. None of the several hundred people who've been to space (some for months) have shown any signs of radiation sickness.
In addition to keeping within known health standards, one precaution will be necessary: there are occasional "storms" on the Sun, generating "solar flares" which give out much more radiation than usual for a few hours. Conveniently these flares can be seen minutes before the particles arrive at the Earth, and so people can take precautions. For example, if a Concorde is in flight at its supersonic cruising altitude of about 20 km when a solar flare occurs, it will reduce speed and reduce its altitude to travel deeper within the atmosphere, thereby protecting the passengers from receiving raised radiation levels. In the same way, orbital hotels will have a "storm shelter" - one or more parts of the hotel in which everyone can shelter from the radiation. The shielding needed is just thick walls, made of some material like metal, concrete or even paper, or just water tanks, since water is a good shield.
We know the above from the experience of the people who've already been to space. These include several hundred people who've been in orbit for a week or two, and a few tens who've been in orbit for a few months. As a result, sufficient research has been done on the effects of living in space to be able to offer safe space tourism services. Those who choose to work in space hotels and other businesses in space will be a new kind of "radiation worker". As such they'll receive more radiation than the general public. This will be at their choice; their health will be closely monitored; and the additional risks they will be taking will be very small. One proviso is that, depending on the facility in question, like radiation workers today, staff will generally only work there after having children, since it's particularly important to prevent damage to the reproductive system. Having babies in space will be a subject for future research!
Health benefits in space
We mustn't forget that there will also be health benefits of living in zero G. People with painful backs will get relief, as they can floating in a swimming pool. Poor blood circulation may well be improved. There's also a possibility that useful discoveries will be made, such as that some kinds of surgery will be easier or safer in zero gravity. So "space hospitals" may become a significant business. But that can happen only once launch costs are cheaper! They're not a priority for research today. However, we can envisage that some people may choose to spend long periods of time in orbit - perhaps in a hotel offering partial-gravity, or even in apartment-blocks!
Low Gravity, Zero G, and Weightlessness
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Many people think that weightlessness is a strange and even dangerous condition, but there's nothing particularly weird about it. Anyone can experience it (briefly!) by just jumping into the air, or for up to about a second by jumping off a wall. While you're airborne your body is in weightlessness. Trampolinists and high divers experience weightlessness for up to a few seconds.
Some people say "they feel their stomach jump", and that's quite right. Normally when standing up your stomach is pressing down on the organs below it (your guts), pulled down by gravity. But when you jump in the air, all parts of your body fall at the same speed, so your stomach no longer presses down on the parts below it. It "floats".
If you "stand on your head" your face goes red because blood which is normally trying to fall down into your feet when you're standing upright now tries to fall into your head. Being in zero G is in between the two - more like lying down. The fluids in your body are no longer trying to fall into your feet, and so people's faces tend to swell and become rounder than they are on Earth.
If you stay in zero G for months, your bones start to lose mass and get thinner, since they're not carrying weight. To counteract this you need to do particular exercises. But for a few days or weeks these effects are no problem. Also, in getting used to zero G your head learns to ignore what your inner ear is saying about your balance, so some people have some giddiness on their return to Earth (hence the chairs sometimes used by Russians returning from space; it's not because they're "basket-cases" as some newspapers have liked to suggest! Overall, a short stay in orbit has no ill effects.
Zero-G is Fun - It's Official
If you're just visiting space in order to enjoy living in zero-G as most tourists will be, it's simply fun - as almost everyone testifies. For example:
Scientists prefer to use the word "micro-gravity" to weightlesness or zero G since, strictly speaking, the effect of gravity is only zero along the single line through the center of mass of an orbiting vehicle along its orbital path. Everywhere else in the vehicle there are "gravity gradient" forces tending to move things either "up" or "down" away from the center of mass. But these forces are very small. For you and I floating in an orbiting hotel, the effect of gravity gradients would be barely noticeable even in a room tens of meters across. (What would happen is that objects would drift very slowly "upwards" or "downwards" - away from the center of mass of the hotel.) In Space Future we use the terms zero G and weightlessness which are well-known and understood.
Zero G versus Artificial G
One of the big debates about orbital accommodation is whether more people will prefer zero gravity or partial gravity. Of the people who have spent time in orbit, there are those who prefer zero gravity, and those who think that partial gravity will be more popular. Of course no-one has yet created a partial gravity environment in orbit, because it's more complex to build a rotating station than a static one.
Some people take the view "What's the point of going to orbit - and then making artificial gravity? Just stay on Earth." Others say that partial gravity (for example 1/6 of Earth gravity - like on the Moon's surface) will be interesting compared to Earth gravity, but will be more convenient for living in than zero gravity, of which short periods for sports will be quite enough.
Like so many matters about space tourism, we don't need to predict. We can find out by experience. Companies will build both hotels providing zero G and hotels providing artificial G of different levels, and customers will decide which they prefer - just as they do with resort hotels on Earth. And the competition between different hotels will drive costs down, expand the market, and make it possible for more and more of us to make the trip.
The Joy of Zero G
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We don't really need to discuss details that people can imagine for themselves, but basically, floating has got to be fun! Anything that makes you giggle in such a situation surely has to be a good thing! Among other effects, being weightless will mean that you and your partner can manoeuvre round each other without danger of either of you - or any parts of you - getting squashed! No more arms or legs going numb!
It's surely also true that there will be a certain "knack" to be learned for "rendezvous and docking". In fact, quite a number of ideas have already been published about this in both fiction and non-fiction books. For example, one author has suggested using special four-legged shorts to hold couples together!
Another has suggested (apparently seriously) that three people will always be needed! (Well, I guess tastes differ - but not for me, thanks!)
Other authors have proposed a range of special furniture and fittings in zero-G bed-rooms for holding onto to prevent you floating around and bumping your head against the walls!
So far, people who've stayed in orbit have generally slept in sleeping bags attached to the wall - but remember, in zero G, walls, floor and ceiling are the same. This has been mainly in order to take up as little of the limited space as possible.
In orbiting hotel rooms, probably a mattress or futon against the "wall", and a sheet or blanket with a large patch of velcro at each corner will be preferred. This will be enough to keep you in place "in bed", and should work for double beds as well as for single beds. But there's clearly plenty of scope for entertaining experimentation! By bedroom designers - and by users!
The cheaper end of the spectrum of sleeping accommodation will be used by hotel staff (and students?) and will be more cramped - something like a sleeping-bag in a broom-cupboard!
Anyway, we can presumably be confident that honeymoons in orbit will become a significant segment of the space tourism market!
Plenty of books have been written about living in space, but they tend to concentrate on the past experience of people who have stayed in orbit. These people have nearly all been in the unusual situation of doing scientific research. And they have all undergone extensive selection and training, because going to orbit is so expensive today that it would be very wasteful if they were ill or failed to do some of their planned work. And so they've mostly been very busy all the time. So most books don't say much about how it will be for people to live in space for fun, for example in an orbiting hotel.
Some astronauts have complained about being in zero G because it makes their work difficult. Objects like screwdrivers and screws don't stay still but float around. You can't use your body's weight to hold things down - you have to brace yourself against something rigid, and so on. It would be easier to do their experiments on the ground.
Short stays
But most of us will be staying in space for a holiday, not working, and for that zero G is fun. Even the most ordinary activities like eating and drinking, having a bath, moving around your room or along a corridor, undressing and getting into bed (with or without a partner) all become new and entertaining in zero G. Children are sure to love it! And once sports facilities are available, a whole new range of activities will be possible.
Living in space for longer periods like a few months or permanently, is more complex, as you have to take precautions against the long-term effects of zero-G and cosmic rays. Living in space for just a few days as a tourist you won't have to worry about most of this.
The fact is that anyone can live in space for a few weeks without any problems, without any ill effects, and in doing so they will have endless opportunity to enjoy the pleasures of zero G.
Keeping fit
Hotel staff will stay in orbit for longer periods of a couple of months at a time, and they'll have to follow a number of health rules. First they'll have to exercise regularly, particularly their leg muscles, because in zero-G without the usual weight acting on them, leg-bones get thinner. This is done with a variety of equipment, such as "exercise-trousers" which have strong elastic between the ankles and the waist which the leg muscles have to stretch, and which puts pressure on the bones and joints.
Radiation
Second, hotel staff will be above the atmosphere which filters a lot of the radiation coming in from space. So orbital hotel staff will be like staff at nuclear power stations, research centers which use radioactive materials, astronauts and other professions: they'll receive higher radiation doses than the general population, which will be closely monitored. As in these other professions, the additional risks will be very small, and staff will receive close health monitoring to prevent any problems arising. Like professional "radiation workers" on Earth, they'll generally be people who don't intend to have more children, since reproduction is particularly sensitive to disruption by radiation.
No barrier to working in space
Of course hotels are going to need a lot of staff. It's easy to see: as tourism reaches a rate of hundreds of thousands of guests per year, most of whom will stay in orbit for a few days, the number of guests in orbit simultaneously will reach thousands - presumably divided between a number of hotels run by competing companies. And since a high ratio of hotel staff will be needed to provide top quality service, there are going to be thousands of professional hotel staff who do an occasional tour of duty in orbit. But even given the extra health risks, I don't think there'll be any shortage of applicants for the job! In fact it's likely to be a popular posting! And it will probably be a long time before any other sort of work employs more people in orbit than hotels. Rather different from the usual image of the future of space activities, but business does what makes money!
Health and Fitness
Lots of people think you need to be a superman to survive the trip to orbit, or to live there. But it's not true. This is just a myth - largely based on fictional stories and movies from before the first space flight was made. (Remember Tintin and friends blacking out? Or the strained expressions on people's faces in old space movies?) The fact is that acceleration of even several Gs is no problem at all so long as you're lying on your back. It doesn't hurt. It's not even hard to breathe. It's like having a baby lying on your chest. But it's not uncomfortable so long as you're lying on something soft. And there's no need for an individually contoured couch!
If you insist on standing or sitting upright, the blood in your head would try to fall towards your feet, and if you didn't take counter-measures you'd probably black out around 5 G, due to falling blood pressure in your head reducing the oxygen supply to your brain. Lying down solves this problem. The only minor inconvenience is that if you want to lift your arms they're very heavy.
The main reason why astronauts and cosmonauts go through such exhaustive selection and training is because their flights are very expensive. And so if a problem arose, like they got appendicitis, and the mission had to be abandoned, this would be a terrible waste of (taxpayers') money. The early astronauts were test pilots, because no-one knew what they were going to experience, and they were flying in dangerous vehicles. But today, essentially anyone who's in reasonable health could go and stay in orbit - if there was an economical launch vehicle available. Certainly anyone who would fly in an aeroplane or ride on a roller coaster will have no problem.
That isn't to say there aren't a number of health "issues". We needn't call them "problems" any more because we know the answers - at least enough to allow us to operate a safe space tourism business. These two issues are "space sickness" and the long-term effects of living in space.
Space sickness
Although staying in space for a short time is quite safe, it's well known that many people who visit space, on the US space shuttle or the Russian "Soyuz" launcher, feel sick, and even vomit. The reason for this is much the same as the reason why some people are sick in cars or ships - "motion sickness" or "travel sickness". (For those who are interested in the details, it's due to the conflict between what your eyes are telling your brain and what your inner ear is telling your brain about your bodily position. Inside a ship your eyes tell you you're not moving, but your inner ears tell you you are. That's why going out on deck helps - your eyes can see you are moving.)
For a long time it was said that "space sickness" is somehow special, and different from other forms of travel sickness. But it isn't. Sure, the precise type of movement of the inner ear is a little different in zero G - just as car-sickness, sea-sickness and air-sickness are a little different from each other. But the good thing is that normal travel sickness medicines are entirely effective against "space sickness", as they are against other forms of motion sickness.
The main reason people are sick on the space shuttle is that they are asked not to take anti-sickness medication, so that NASA staff can do research on the phenomenon! It is indeed possible to do "research" on space sickness - just as it would be possible to do research on sea sickness. But there's no need to. Brain scientists don't fully "understand" sea-sickness - but the cruise industry doesn't pay them to do research. They just make it easy for passengers to get hold of effective medication! The commercial approach - low cost and effective. The same will be done for space tourism, and no-one will need to be sick. Unfortunately, most journalists still don't know this, and trot out the same old line "It's a pity that everyone's going to be sick, so it'll never get very popular..."
Bird legs and blocked noses
One phenomenon - it can't really be called a problem - is the fact that in zero gravity, as the fluids in your body are no longer pulled down towards your feet by gravity, it tends to accumulate higher up in your body, creating what some people call "bird legs" - the muscles of your legs appear smaller than on Earth - and also "fat-face" (or perhaps more appropriately "Moon-face"). Your family and friends will look a bit different in zero G! (You can see this in photos of astronauts.)
There's a serious side to it which is that this also gives you a slight feeling of nasal congestion which may be uncomfortable for some people. So using decongestants may be popular. In addition, having a head cold may be more unpleasant than on Earth - so medication to suppress the symptoms (now common on Earth) may be desirable.
Unfortunately astronauts and cosmonauts don't go to space if they have a cold - so we don't have good information on this! This is an example of how the experiments desirable for space tourism are different from the experiments that space agencies do aimed at long term space flight, etc. As they get wise, maybe you'll see an advertisement saying "Astronauts wanted - must have streaming cold".
Long term health effects of living in space
On Earth your muscles and bones are continually subject to gravity. This exerts forces on them, generally putting the muscles in tension and the bones in compression. When you're floating in zero-G most of these forces disappear, and your muscles are very relaxed. (One result of this is that people living in orbit don't get very tired, and tend to sleep less than down here - 3 - 4 hours is said to be common.) This condition is no problem for a week or so, but if it continues for months, the muscles start to shrink through lack of use. (When you train a lot, your muscles grow in volume; when you don't use them they shrink!) This includes the muscles of the heart, because pumping blood in zero G is much easier than in 1 G. So astronauts and cosmonauts staying in orbit for months make time for daily physical exercise to keep their muscle strength up so that they won't be weak when they get back to Earth.
Another effect of living in weightlessness is that, like your muscles, your bones also lose mass. Though bones seem pretty solid, they're alive, and like many biological systems they're in equilibrium between building themselves up and breaking themselves down. So they continually take calcium from the blood and release calcium into the blood. But when the stresses on the bones fall, as when you're floating around in zero G, less calcium is taken up from the blood because the cells sense less need for it. For a week or so this is no problem. But if it continued for months, your bones would get significantly weaker. So people who spend long periods in space have to use special trousers with strong elastic joining the belt to the ankles, which puts compressive forces on the leg bones and joints, and convinces them to take up more calcium. It may not be so elegant, but by doing this they don't lose so much bone mass. Further research will probably develop even better remedies. But we have to select priorities. It's much more urgent to get launch costs down - by developing a space tourism industry, among other things - than to do this research soon. Current knowledge is quite adequate for building a medically safe orbital tourism industry - and after that it will be much cheaper to do this research. That would be much better than continuing to spend hundreds of $millions to perfect this treatment when there's no urgent need for it.
Space radiation
Nuclear radiation, including both high-energy particles such as protons and other atomic nuclei, and high-frequency electro-magnetic waves, X-rays and Gamma-rays, can damage biological cells by ionizing molecules inside them. Most of the time this damage is simply repaired automatically. But if a lot of radiation is absorbed, the damage can overcome the body's ability to repair it, and the damaged cells may die or may become cancerous (that is, growing uncontrollably).
In space, all of these types of radiation are present to some extent - protons and electrons trapped in the Earth's radiation belts and coming from the Sun, and energetic particles coming from further away ("cosmic radiation"). The Earth's atmosphere protects us from them to a large extent (but not completely; people living at high altitude receive considerably higher "background radiation" doses than those living lower down!) Roughly speaking, the longer you stay in space, and the higher the orbit you travel in, the more radiation you absorb, and so the higher the chance of damage. In most cases, spending a few days in orbit will pose no risk at all. The radiation absorbed will be equivalent to the average radiation you receive in a year on Earth (from X-rays, background radiation, and environmental pollution). There are long-established international standards for the recommended maximum radiation doses both for the general public, and for "radiation workers" - people working in hospitals who use nuclear materials, in the military, in nuclear power stations, and astronauts. None of the several hundred people who've been to space (some for months) have shown any signs of radiation sickness.
In addition to keeping within known health standards, one precaution will be necessary: there are occasional "storms" on the Sun, generating "solar flares" which give out much more radiation than usual for a few hours. Conveniently these flares can be seen minutes before the particles arrive at the Earth, and so people can take precautions. For example, if a Concorde is in flight at its supersonic cruising altitude of about 20 km when a solar flare occurs, it will reduce speed and reduce its altitude to travel deeper within the atmosphere, thereby protecting the passengers from receiving raised radiation levels. In the same way, orbital hotels will have a "storm shelter" - one or more parts of the hotel in which everyone can shelter from the radiation. The shielding needed is just thick walls, made of some material like metal, concrete or even paper, or just water tanks, since water is a good shield.
We know the above from the experience of the people who've already been to space. These include several hundred people who've been in orbit for a week or two, and a few tens who've been in orbit for a few months. As a result, sufficient research has been done on the effects of living in space to be able to offer safe space tourism services. Those who choose to work in space hotels and other businesses in space will be a new kind of "radiation worker". As such they'll receive more radiation than the general public. This will be at their choice; their health will be closely monitored; and the additional risks they will be taking will be very small. One proviso is that, depending on the facility in question, like radiation workers today, staff will generally only work there after having children, since it's particularly important to prevent damage to the reproductive system. Having babies in space will be a subject for future research!
Health benefits in space
We mustn't forget that there will also be health benefits of living in zero G. People with painful backs will get relief, as they can floating in a swimming pool. Poor blood circulation may well be improved. There's also a possibility that useful discoveries will be made, such as that some kinds of surgery will be easier or safer in zero gravity. So "space hospitals" may become a significant business. But that can happen only once launch costs are cheaper! They're not a priority for research today. However, we can envisage that some people may choose to spend long periods of time in orbit - perhaps in a hotel offering partial-gravity, or even in apartment-blocks!
Low Gravity, Zero G, and Weightlessness
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Many people think that weightlessness is a strange and even dangerous condition, but there's nothing particularly weird about it. Anyone can experience it (briefly!) by just jumping into the air, or for up to about a second by jumping off a wall. While you're airborne your body is in weightlessness. Trampolinists and high divers experience weightlessness for up to a few seconds.
Some people say "they feel their stomach jump", and that's quite right. Normally when standing up your stomach is pressing down on the organs below it (your guts), pulled down by gravity. But when you jump in the air, all parts of your body fall at the same speed, so your stomach no longer presses down on the parts below it. It "floats".
If you "stand on your head" your face goes red because blood which is normally trying to fall down into your feet when you're standing upright now tries to fall into your head. Being in zero G is in between the two - more like lying down. The fluids in your body are no longer trying to fall into your feet, and so people's faces tend to swell and become rounder than they are on Earth.
If you stay in zero G for months, your bones start to lose mass and get thinner, since they're not carrying weight. To counteract this you need to do particular exercises. But for a few days or weeks these effects are no problem. Also, in getting used to zero G your head learns to ignore what your inner ear is saying about your balance, so some people have some giddiness on their return to Earth (hence the chairs sometimes used by Russians returning from space; it's not because they're "basket-cases" as some newspapers have liked to suggest! Overall, a short stay in orbit has no ill effects.
Zero-G is Fun - It's Official
If you're just visiting space in order to enjoy living in zero-G as most tourists will be, it's simply fun - as almost everyone testifies. For example:
- The first US woman to visit space, Sally Ride, said it was "the greatest fun of her life".
- After the repeated "parabolic flights" on board an aeroplane to produce 20-second periods of zero gravity while filming "Apollo 13", Tom Hanks said he never thought he'd have such fun again. (He will - once space tourism services start!)
- Shannon Lucid, after returning from spending 6 months on board the Russian space station Mir in 1996, said that if she had the opportunity she'd return to orbit on the next shuttle flight. "You just sort of get used to floating around." And remember - she was working busily in a cramped craft with one small window at the end of a tube - with a cover which was usually closed! Imagine how much more fun it will be when people are staying for pleasure and relaxation in hotel-like surroundings with picture-windows facing Earth!
Scientists prefer to use the word "micro-gravity" to weightlesness or zero G since, strictly speaking, the effect of gravity is only zero along the single line through the center of mass of an orbiting vehicle along its orbital path. Everywhere else in the vehicle there are "gravity gradient" forces tending to move things either "up" or "down" away from the center of mass. But these forces are very small. For you and I floating in an orbiting hotel, the effect of gravity gradients would be barely noticeable even in a room tens of meters across. (What would happen is that objects would drift very slowly "upwards" or "downwards" - away from the center of mass of the hotel.) In Space Future we use the terms zero G and weightlessness which are well-known and understood.
Zero G versus Artificial G
One of the big debates about orbital accommodation is whether more people will prefer zero gravity or partial gravity. Of the people who have spent time in orbit, there are those who prefer zero gravity, and those who think that partial gravity will be more popular. Of course no-one has yet created a partial gravity environment in orbit, because it's more complex to build a rotating station than a static one.
Some people take the view "What's the point of going to orbit - and then making artificial gravity? Just stay on Earth." Others say that partial gravity (for example 1/6 of Earth gravity - like on the Moon's surface) will be interesting compared to Earth gravity, but will be more convenient for living in than zero gravity, of which short periods for sports will be quite enough.
Like so many matters about space tourism, we don't need to predict. We can find out by experience. Companies will build both hotels providing zero G and hotels providing artificial G of different levels, and customers will decide which they prefer - just as they do with resort hotels on Earth. And the competition between different hotels will drive costs down, expand the market, and make it possible for more and more of us to make the trip.
The Joy of Zero G
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We don't really need to discuss details that people can imagine for themselves, but basically, floating has got to be fun! Anything that makes you giggle in such a situation surely has to be a good thing! Among other effects, being weightless will mean that you and your partner can manoeuvre round each other without danger of either of you - or any parts of you - getting squashed! No more arms or legs going numb!
It's surely also true that there will be a certain "knack" to be learned for "rendezvous and docking". In fact, quite a number of ideas have already been published about this in both fiction and non-fiction books. For example, one author has suggested using special four-legged shorts to hold couples together!
Another has suggested (apparently seriously) that three people will always be needed! (Well, I guess tastes differ - but not for me, thanks!)
Other authors have proposed a range of special furniture and fittings in zero-G bed-rooms for holding onto to prevent you floating around and bumping your head against the walls!
So far, people who've stayed in orbit have generally slept in sleeping bags attached to the wall - but remember, in zero G, walls, floor and ceiling are the same. This has been mainly in order to take up as little of the limited space as possible.
In orbiting hotel rooms, probably a mattress or futon against the "wall", and a sheet or blanket with a large patch of velcro at each corner will be preferred. This will be enough to keep you in place "in bed", and should work for double beds as well as for single beds. But there's clearly plenty of scope for entertaining experimentation! By bedroom designers - and by users!
The cheaper end of the spectrum of sleeping accommodation will be used by hotel staff (and students?) and will be more cramped - something like a sleeping-bag in a broom-cupboard!
Anyway, we can presumably be confident that honeymoons in orbit will become a significant segment of the space tourism market!