What happens to you when you can't walk for a year? When you can't have sex? Or smell flowers? What happens if you vomit in your helmet during a space walk? Is it possible to survive a bailout at 17,000 miles an hour? Space is a world devoid of the things we need to live and thrive: air, gravity, hot showers, fresh veg, privacy, beer. To answer these questions, space agencies set up all manner of quizzical and startlingly bizarre space simulations, and as Mary Roach discovers, it's possible to preview space without ever leaving Earth.