Floating, Eating, Sleeping: How Astronauts Live in Space, and a Talk on Your Favourite Planet

Mugisha: Good evening, and welcome to Science Hour. Tonight we ask what it is like to live about four hundred kilometres above our heads, on the International Space Station. With me is Dr Aline Uwase, who studies how the body copes with space. Dr Uwase, let's begin with the morning. How does an astronaut wake up?

Dr Uwase: With an alarm, just like you. The station goes round the Earth every ninety minutes, so the Sun rises and sets many times a day. If the crew followed the Sun, they would never sleep properly. So they keep to a fixed timetable that matches a twenty-four-hour day.

Mugisha: And where do they sleep? There is no "down" to put a bed on.

Dr Uwase: Exactly. Each astronaut has a tiny cabin, about the size of a phone box, with a sleeping bag fixed to the wall. The important thing is to sleep near a fan. Warm air doesn't rise in weightlessness, so if the air around you doesn't move, the carbon dioxide you breathe out collects round your head. You'll wake up with a terrible headache.

Mugisha: That's frightening. What about breakfast?

Dr Uwase: Far better than on the early missions, when most food was freeze-dried. Drinks and soup come in sealed bags with straws, because liquid would float out of a cup in drops. Knives and forks are held on the table with magnets. And many astronauts ask for spicy food, because in space their sense of taste seems duller.

Mugisha: How do they keep clean? Is there a shower?

Dr Uwase: No. There's no shower on the station. Astronauts wash with wet towels.

Mugisha: I understand exercise is your speciality.

Dr Uwase: It is. On Earth, gravity pulls on your skeleton all day, and your bones and muscles stay strong because they have work to do. In space that work disappears, so the body starts to lose bone and muscle. That's why every astronaut exercises for about two hours a day, on a treadmill, a bicycle and a machine that works like lifting weights. If an astronaut skips exercise for months, she'll come home too weak to walk easily.

Mugisha: Two hours a day! I don't manage two hours a week.

Dr Uwase: (laughing) Neither do most of us. But up there it isn't a hobby; it's part of the job.

Mugisha: Water must be precious, too.

Dr Uwase: Very. Every litre has to be launched from Earth, which is expensive. So the station recycles about ninety-eight per cent of its water. Moisture from the crew's breath and sweat is collected from the air, and even urine is cleaned and turned back into drinking water.

Mugisha: I think some of our listeners have just put down their tea! A last question: would you go?

Dr Uwase: Tomorrow, if they asked me. If I go one day, I'll take a photograph of Lake Kivu from orbit. But I know what I'd miss most: the sound of rain on the roof.

Mugisha: Dr Aline Uwase, thank you.