for National Geographic News
Scientists working toward a manned Mars mission say they're closing in on a new, high-tech material that can shield astronauts from deadly deep-space radiation.
Known as graphite nanofiber, the new material would be much lighter than the dense materials used on Earth as radiation shielding in nuclear power plants.
That's good, because radiation is one of the biggest dangers to long-distance space travelers.
Intense bursts from solar flares can kill quickly. But even normal background radiation levels in interplanetary space are high enough to pose dangers, including an increased risk of cancer. (Related: "Space Weather Could Scrub Manned Mars Mission" [August 9, 2005].)
While adequate shielding can easily be made with existing technology—a few feet of concrete would work admirably—such materials are too heavy to launch into space.
"If we don't get off the ground, we are not in business," Ram Tripathi, a senior research scientist at NASA's Langley Research Center, said at a meeting of the American Physical Society in Denver, Colorado, earlier this month.
This thorny safety issue can't be solved the same way on a Mars mission as it was on the International Space Station or the Apollo expeditions to the moon, Tripathi added. (See a photo gallery of the top photos from the space station.)
The Apollo trips, he said, were "little hops," so there wasn't time for background exposures to reach dangerous levels.
And in the space station, astronauts are close enough to Earth for its magnetic field to protect them from the worst types of radiation.
On occasions when short-lived solar flares overpower that protection, the astronauts can huddle in a cramped radiation shelter that doesn't add vastly to the station's weight.
But in deep space the radiation takes the form of larger particles that are more difficult to stop.
SOURCES AND RELATED WEB SITES