The astronauts launching on space shuttle Atlantis this afternoon will experience fatigue, muscle and bone-density loss, and a host of other space ills during the next couple of weeks. But their counterparts who will one day travel to Mars face greater problems -- their immune systems will be compromised, thanks to genes that behave differently in space.
Spaceflight changes the activity of genes that control immune and stress response, according to a new study of space-flown mice at the University of Arizona.

They found that 970 genes in the space mice were regulated differently, according to a UA press release. When the changes were averaged, the team found 12 genes were significantly changed in all four mice. The genes affect signaling molecules that play a role in programmed cell death, Lebsack says.
The varying gene expression could mean just that, however. Many of the genes whose activity was down-regulated in the space-flown mice play important roles in maintaining that balance," Lebsack said. "Potentially, you could get more cell death aboard a spacecraft because of these differences."
Other immune-system worries stem from stress, a tough work schedule and close living quarters. NASA has long studied how to protect astronauts from space bugs, and a study flying up on Atlantis later today will further those efforts. Bacteria that are harmless on Earth can cause problems in space -- if they're tough enough to live in that harsh environment, they might become resistant to antibiotics, too. Plus, gravity makes bacteria grow differently. In the latest experiment, scientists want to find out whether certain kinds of bacteria will grow on special surfaces designed to prevent them.

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These problems are not caused by space or spaceflight, but by zero gravity, right? There is no compelling reason astronauts in long-term spaceflight should experience more than temporary zero-gravity. It would be more valuable to know what percentage of full gravity is adequate to maintain the human body. I remember the Lawrence Livermore Labs proposed Mars Mission that included rotating inflatable kevlar modules to maintain gravity (and was much, much less expensive that options proposed by NASA). NASA and Congress responded to the proposed mission by banning the Dept. of Energy from any future funding of such research outside NASA.
So how's that kevlar balloon protect fron radiation?
i dont want to go into space anymore