What happens when you sneeze in space? And how do you go to the loo? Astronaut Helen Sharman is the woman with all the answers to these questions and a lot more besides.

Sheffield born Helen became Britain's first astronaut when she spent eight days on the Mir Space Station in May 1991 as part of the Soviet space mission project Juno. Her job was to conduct experiments to see how seeds, plants and vegetables grow in space and also to monitor the effects of weightlessness on the human body.

She had to undergo 18 months of training at cosmonaut school in Star City near Moscow, where she learned to speak Russian, became weightless in a plane that did endless loop the loops and spun round in a giant ball contraption until she was dizzy. Helen was also measured in 54 different places to make sure her space suit was a perfect fit. ("The only made to measure suit I've ever owned," she joked.)

Helen's fascinating stories about her time on Mir reveal a weightless world where even the simplest earth tasks are a real challenge. She had to wear specially designed button down space clothes to prevent items of clothing floating up around her head. And when she wanted to get some sleep, Helen had to make sure her sleeping bag was tied down so that she did not drift off around the space station during the night. (Except night time in space doesn't really exist because Mir orbits the earth 16 times every 24 hours, so the crew see a series of sunsets and sun rises every day.)

Astronauts can't put the kettle on when they fancy a drink. Helen had to drink her coffee through a straw from a flat plastic packet. Which brings us on to that delicate subject - how to go to the loo in space. A space toilet looks a bit like a humble portaloo but, Helen assures us, it's a lot less smelly due to a high tech suction gadget.

And even more amazingly is the way the astronauts can recycle the toilet's contents into water pure enough to drink (wouldn't like to taste that). Or they can zap the water with an electric current to separate the valuable oxygen from the hydrogen (water is made up from oxygen and hydrogen, for all you non-boffins).

But what does happen if you sneeze in space? Because of the weightlessness, the force of a sneeze propels the body backwards so that you become, in effect, a human rocket. And Helen should know -she sneezed an average of 20 times an hour while in space because of the weightless dust, which just floats around getting up astronauts' noses!

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