for National Geographic News
Mutant hitchhikers may become a major hurdle in the quest to send humans deeper into the galaxy, scientists say.
That's because no matter how fit astronauts feel at liftoff, they're likely to be carrying disease-causing microbes such as toxic E. coli and Staphylococcus strains.
Charged particles zipping through space, known as cosmic rays, can mutate the otherwise manageable microbes, spurring the bugs to reproduce quicker and become more virulent, recent studies show.
At the same time, exposure to cosmic rays and the stresses of long-term weightlessness can dampen the human immune system, encouraging diseases to take hold.
Aboard spaceships without advanced medical care, illness could cripple human missions to Mars and beyond, according to a new report published this month in the Journal of Leukocyte Biology. (Get Mars exploration pictures, facts, and more.)
"What is the interest of having people on Mars if they cannot efficiently perform the analyses and studies scheduled during their mission?" said study co-author Jean-Pol Frippiat, an immunologist at Nancy University in France.
Cells Change in Zero G
For the new report, Frippiat and colleagues analyzed more than 150 studies of the effects of space flight on humans, animals, and pathogens. (Get the scoop on how low gravity makes it harder to get pregnant in space.)
On Earth humans are protected from the effects of cosmic rays, because most of the particles are deflected by the planet's magnetic field.
Out in space, however, such protections vanish, and cosmic radiation can cause mutations when it strikes the DNA inside cells. (Find out more about where cosmic rays come from.)
The absence of gravity can also be detrimental to human health, because weightlessness allows structures to shift around within cells.
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