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lunes, 1 de junio de 2009

Space Torso Reveals Cancer Risk for Astronauts

Radiation detectors laced into dummy torsos that flew aboard the International Space Station bear sobering news for NASA and other agencies that want send humans to Mars: Houston, there is a problem.

Cancer and other health concerns skyrocket for astronauts living beyond the protective environment of Earth's magnetic shield for periods of six months or longer, say researchers looking into the effects of radiation on the human body.

Astronauts aboard the International Space Station, which orbits about 200 miles above the planet, are somewhat protected from harmful solar and cosmic radiation by Earth's magnetic field. Travelers to the moon, Mars and other destinations won't have this shielding.

"The radiation we see (on the station) is more benign that what they'll see going on a lunar or a Mars mission," said Kirk Shireman, NASA's deputy manager for the space station program.In addition to radiation studies under way at the Brookhaven National Laboratory, NASA and its partners on the station program have been flying torsos with embedded radiation sensors to gauge the potential damage to internal organs. Astronauts also wear dosimeters all the time and extra care is taken to monitor radiation levels while crewmembers are outside the station on spacewalks, Shireman said.

The information collected so far confirms that NASA's current guidelines for assessing radiation risks are pretty much on target, said Francis Cucinotta, a doctor and researcher who heads radiation studies at the Johnson Space Center in Houston.

NASA is planning to return astronauts to the moon by 2020 and establish a base, before moving on to human missions to Mars and other destinations under a new exploration initiative known as Constellation.

Cucinotta figures the agency has about five years to come up with some solutions to the radiation problem or find evidence that refutes current assessments of the risks.More shielding on moon and Mars ships probably isn't the answer, Cucinotta told Discovery News. The additional weight would make the spacecraft too heavy to launch with today's technologies.

Faster ships to Mars may be one answer -- the current round-trip time is about 18 months -- or perhaps some sort of magnetic shielding that repels space radiation, though neither technology exists today.

Another possibility is to select astronauts based on genetic factors that would make them more resilient to the effects of space radiation.

"NASA and the other agencies may have to do it, but it'd be kind of disappointing to have to have these additional qualifications to be an astronaut," Cucinotta said.

Pharmaceuticals that could repair cell damage and other harmful effects of spaceflight, unfortunately, do not seem to be an answer.

"We'd all be cured of cancer on Earth if we knew how to do this," Cucinotta said.

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