By Sean Treacy — Imagine life on a spaceship headed to Mars. You
and your five crewmates work, exercise, and eat together every
day under the glow of fluorescent lights. As the months pass,
the sun gets dimmer and communication with Earth gets slower.
What does this do to your body? According to an Earth-based
experiment in which six volunteers stayed in a windowless
"spaceship" for nearly a year and a half, the monotony, tight
living space, and lack of natural light will probably make you
sleep more and work less. Space, for all intents and purposes,
turns you into a couch potato. A mission to Mars would take
about 520 days-including the months it takes to travel there and
back and the time spent on the Red Planet. But the longest any
human has spent off Earth is 437 days straight, a record set in
1995 by Russian cosmonaut Valeri Polyakov, who was orbiting
relatively close to home in the space station Mir. Polyakov
seemed to bear the burden of long space flight fairly well, but
many questions remain about ju