As a chemist, Helen Sharman finds the chemistry of living in space fascinating. As an astronaut, her health and happiness depended on it
This piece is about living in space, in response to popular demand. In particular it’s about some of the life support systems that have been developed to enable people like me to stay alive, healthy and comfortable enough to do a job and then return to terrestrial life unimpeded by their cosmic experience.
Some people have spent many months at a stretch in weightless conditions, with the Russian doctor Valeri Polyakov famously doing a stint of over 14 months. His aim was to return to Earth fitter than when he launched; he didn’t, though he survived admirably and proved that long duration missions are possible without the need for the ‘artificial gravity’ popularised by science fiction.
So what are the effects of weightlessness on the human body? The obvious changes in daily life are relatively easy to cope with, like not being able to lie down (you don’t need to), sit down (ditto), stand up (ditto again) or have well-behaved hair. Men often have a haircut ‘like a hedgehog’ as Sergei Krikalev, my engineer, said after his pre-flight crop. I was able to enjoy having an off-camera hairstyle which would have put envy into the heart of the punkiest of mohican wearers.
No, the first discomfort I noticed was that my head felt stuffy, like the feeling you get after standing on your head for a while. Our hearts are accustomed to pumping blood ‘up’ to our heads, something no longer necessary as soon as the final rocket stage is jettisoned and the feeling of weightlessness takes over. It is the most natural, relaxing feeling. I forgot what it is like to feel weight, though now I still dream about floating in mid air, touching nothing except my clothes.
Anyway, blood and other body fluids, no longer pulled down towards my feet, adapted to their new environment by shifting towards my head. Over the next couple of days, my kidneys excreted about two litres of urine more than would be expected for the amount of water that I had drunk and I felt much more comfortable.
However, you can’t lose that much fluid without there being a knock-on effect on the body’s chemistry, which is one of the reasons why astronauts lose calcium and potassium, amongst other elements. This affects bones and muscles so the right diet and exercise regime is particularly important for astronauts. I love the way that life totally disregards the traditional boundaries between the sciences. A simple hydrostatic pressure change alters chemical equilibrium which itself impacts on anatomy. You can read more about muscle wastage in space here.
It is costly in many terms to transport stuff 400km upwards from the Earth’s surface, so nothing is wasted if at all possible. This includes urine, for which the Russians developed an ingenious recycling system. First of all, collect the urine. You pee into a funnel, attached by a tube to a container. You have to use muscular effort to squeeze it out, but otherwise the only difference is that air is flushed through the funnel to carry the urine away. It goes through filters, treatment with silver ions and heating to make the ’urine-water’ clean enough to drink (yes, really). However, the psychologists don’t like astronauts to drink the contents of their toilet so most drinking water is brought up from Earth or condensed from the moist air on cold metal panels.
Urine-water is electrolysed, thus separated into hydrogen and oxygen. The oxygen is mixed with space station air to be breathed and the hydrogen is vented into space. Research into using the hydrogen to make carbohydrates by combining it with breathed-out carbon dioxide has been going on for many years. Currently, the carbon dioxide is absorbed in cartridges of lithium hydroxide and other chemicals we excrete, like ammonia from the breakdown of urea in sweat, are absorbed on charcoal. The NASA website has more information about the life support systems on the International Space Station.
You can see how just staying alive requires a combination of engineering, science and technology. As climate change continues apace, it is important that young people are encouraged to keep all their sciences going for as long as possible so that future scientists are better able to join up studies and link their work to real life on, and off, Earth.