Mutant Diseases May Cripple Missions to Mars, Beyond

Ker Than
for National Geographic News
November 4, 2009
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.

(Related: "Lethal Bacteria Turn Deadlier After Space Travel.")

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.

The immune system is particularly vulnerable, since it relies on cell-to-cell interactions for ridding the body of harmful pathogens.

One study, for instance, found that astronauts who had recently returned from space had white blood cells that were less effective at seeking out and destroying E. coli bacteria.

Left untreated, E. coli can cause severe cramps, vomiting, and diarrhea as well as kidney and blood-cell damage that can lead to fatal complications.

Vitamin Boosts, Faster Rides

Keeping astronauts healthy on long-duration missions will be a major challenge for NASA and other space agencies, agreed Gerald Sonnenfeld, an immunologist and vice president of research at Binghamton University.

"There is a potential for a problem in the immune system to create an issue in a long-term spaceflight, and this must be seriously investigated," said Sonnenfeld, who was not involved in the new report.

But the problems are not insurmountable, Sonnenfeld said. For instance, the report authors note that using vitamins and compounds to help boost the immune system is one promising avenue for future research.

Alternatively, the risks to astronauts could be reduced by shortening the time they have to spend in space, said Millie Hughes-Fulford, an immunologist at the University of California, San Francisco, and a former NASA astronaut.

NASA is currently experimenting with a so-called plasma drive that could potentially cut the transit time to Mars, for example, down from about nine months to three, Hughes-Fulford said.

Research into astronaut health was once much more active, Binghamton University's Sonnenfeld added. (Find out why one astronaut recently spent months in space wired with electrodes and recording the smells of his underwear.)

But "as [space agencies] saw that there were really no serious issues on shorter term flights and even longer space station missions, they cut back on the interest and funding," he said.

"I think [astronaut health is] back on the radar screen now that [NASA] is considering longer-term missions."

© 1996-2008 National Geographic Society. All rights reserved.