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NASA software scalpel helps doctors practice operations. Technologies such as this have the potential for improving health care at remote places on Earth (and space) by linking them with the best medical minds and facilities. Courtesy Ames Research Center, NASA


To date, only accidents have killed space travelers. And yet, after 40 years of space travel, it's clear that some critical physical effects can't be ignored. "Almost every component of the body undergoes change during spaceflight," says Ronald White, associate director of the National Space Biomedical Research Institute in Houston. "There are virtually no systems that are not affected." In fact, he says the biggest single medical surprise of space travel is the extraordinary "plasticity" of body systems in weightlessness. It may seem paradoxical -- since every Earthling must, at one time or another, have longed to escape gravity -- but weightlessness (technically "microgravity") poses the biggest medical danger to space travelers. In low earth orgit, radiation is not a big deal. It's a different story with interplanetary travel...

Under the ray gun
Before we get to weightlessness, let's talk radiation. Occupants of the space station are somewhat protected by Earth's magnetic field, which detours electrically-charged particles away from Earth.

And while they are exposed to strong ultraviolet light, the aluminum skin of a spaceship blocks that.

Add it up, and an unshielded astronaut in low-Earth orbit gets about 10 times as much radiation as strikes the ground, according to White (see "Weightlessness and... " in the bibliography).

In deep space, alpha rays, gamma rays, and heavy ions become more problematic, since shielding is heavy and expensive to launch. During intense solar storms, crews may be able to retire to a small, shielded area. Because radiation causes damage by altering DNA in the genes, it may be possible to use drugs or diet to accelerate the body's normal DNA repair mechanism.

What about our breathing apparatus in a confined environment? John West, who studies lung function of the University of California at San Diego, observes that the atmosphere inside the spaceship may be polluted with aerosols or toxic chemicals. A worse hazard is smoke after a fire like those that threatened to consume Russia's Mir spacecraft.

Spacefarers who venture outside the ship can get the bends, a painful accumulation of nitrogen in the blood that plagues deep-sea divers. Dial 911!Although West sees no insuperable respiratory obstacles, he says detailed pulmonary data on long-term missions at the space station could still yield surprises.

Dial 911!
What happens if a traveler has a medical emergency? Desmond Lugg, head of polar medicine for the Australian Antarctic Division, says that in 50 years of exploration, "We've seen brain aneurysms (bleeding), coronaries. Anything that can happen we've seen happen."

Lugg -- and many within the space bureaucracy -- look to lessons from Antarctic exploration to learn what will happen on long-term space travel; "We see the Antarctic as an analog for space travel," says Lugg. In fact, he says, records from the On a backlit table, a scientist uses a stylus to virtually cut and paste clear, accurate three-dimensional (3-D) images made from a series of scans of the human headAustralian outposts that are inaccessible for eight months a year provide information about "the most isolated people on the planet." Each Australian outpost gets a jack-of-all-trades doctor, Lugg says, who, like spacebound docs, can deal with some emergencies, depending on their training and equipment.

Space travelers may eventually want to rely on "telemedicine," robots that do surgery under the command of Earthbound experts. Yet despite progress, telemedicine is problematic for interplanetary space travel, since radio signals take up to 40 minutes to reach Mars. Says Lugg, "I'd worry if some sort of robot was doing surgery and you pulled a lever on Earth," and nothing happened until 40 minutes later.

illustration/cartoon of a satellite with the letters s.o.s. on it.Bailing out
While astronauts bound for Mars could not turn back, reaching the hospital is simpler from Earth orbit; a simple rescue craft can be docked to the space station for quick return to Earth. We wanted to ask NASA about this and other matters related to their costly program on human occupation of space, but they apparently had more pressing business.

Although radiation, heart attacks and fires make lousy copy for a travel-agency ad, space travel can be more exciting than a complementary trip to Vegas. Says White, "For the most part, the trip is not only pleasant... but overwhelmingly positive. The traveler has the opportunity to look out the window, see the world in a new light, float, feel free of some of the restrictions of weight."

He didn't mention osteoporosis. Is bone thinning the biggest single threat to astronauts?

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