SURVIVING IN SPACE Motion sickness troubles more than two-thirds of all astronauts upon reaching orbit, even veteran test pilots who have never been airsick. Though everyone recovers after a few days in space, body systems continue to change. Deprived(丧失) of gravity information, a confused brain creates visual illusions. Body fluids surge to chest and head. The heart enlarges slightly, as do other organs. Sensing too much fluid, the body begins to discharge it, including calcium, electrolytes (解液) and blood plasma (血浆). The production of red blood ceils decreases, rendering astronauts slightly anaemic (贫血的). With the loss of fluid, legs shrink. Spinal (脊骨的) discs expand, and so does the astronaut--who may gain five centimeters and suffer backache. Though the .process may sound terrible, astronauts adjust to k, come to enjoy it and seem no worse for wear-at least for short missions such as space shuttle flights that last a week or two. During longer flights, however, physiology enters an unknown realm. As director of Russia’’s Institute for Biomedical Problems from 1968 to 1988, Oleg Gazenko watched cosmonauts return from long flights unable to stand without fainting, needing to be carried from the spacecraft. "We are creatures of the Earth,” Gazenko told me. "These changes are the price of a ticket to space". Americans returning from months-long flights on Mir, the Russian space station, also paid the price, suffering losses in weight, muscle mass and bone density. NASA geared up to see how--even if--humans would survive the most demanding of space ventures, a mission to Mars, which could last up to three years. "We don’’t even know if a broken bone will heal in space," said Daniel Goldin, NASA’’s administrator. To get answers in 1997 Goldin established the National Space Biomedical Research Institute (NSBRI), a panel of experts from a dozen leading universities and research institute. NSBRI will study biomedical problems and by 2010 will present NASA with a "go" or "no go" recommendation on a Mars mission. Jeffrey Sutton, leader of the medical systems team at the NSBRI, has treated the head trauma, wounds, kidney stones and heart rhythm irregularities that one could encounter on the way to Mars. On the spacecraft he envisions, Mars-hound in the year, say, 2018, there may lurk harmful bacteria or carbon monoxide. No problem. The deadly substances will be detected by smart sensors-microprocessors no bigger than a thumbnail--that wander at will through the spacecraft, communicating their finds to a computer that warns the crew. To cope with infection, Sutton plans a factory to make drugs, even new ones, to cope with possible organisms on Mars. Miniature optical and ultrasound devices will image body and brain, while a small X-ray machine keeps track of any bone loss. Smart sensors embedded in clothing will monitor an astronaut’’s vital functions. The crew will be able to craft body parts, Sutton says, precisely tooled to an astronaut’’s personal anatomy and genome stored in computer memory. Researchers are building artificial liver, bone and cartilage (软骨) tissue right now. Lying in wait beyond the Earth’’s atmosphere, solar radiation poses additional problems. The sun flings billions of tons of electrically charged gas into space, relegating Earth’’s volcanic eruptions to mere hiccups. Nevertheless, NASA officials are confident the accurate monitoring will warn astronauts of such events, allowing the crew to take refuge in an area where polyethylene (乙烯) shielding will absorb the radiation. A second kind of radiation, cosmic rays from the Milky Way or other galaxies, is a more serious threat--possessing too much energy, too much speed for shielding to be effective. "There’’s no way you can avoid them," says Francis Cxueinotta, manager of NASA’s Johnson Space Centre. "They pass through tissue, striking ceils and leaving them unstable, mutilated or dead. Understanding their biological effects is a priority." Another major concern is the psychological health of astronauts. And there’’s a new stressor on a three-year Mars Mission-people, other members of the crew. NASA found that the stresses of isolation and confinement can be brought on rapidly simply by giving people few tasks. Mir astronaut Andrew Thomas described how six astronauts were confined in a 12-foot square room for a week. "If you give them little to do, stress can be achieved in a couple of days, says Thomas. Will NSBRI meet Daniel Goldin’’s 2010 deadline for a decision on Mars "Yes, we will perhaps even before. We’’re very confident," says Laurence Young, the director of NABRI. Mean while some of NSBRI’’s research may bear fruit on Earth. The institute has made one discovery that promises to save many people at risk of sudden cardiac death, usually brought on by a heart rhythm disorder called ventricular fibrillation. This kills 225,000 people in the US each year. Richard Cohen, head of the NSBR1 cardiovascular (心血管的) team, explained that zero gravity may-emphasizing "may"--incite this condition in astronauts. So the team invented a noninvasive diagnostic device that measures extremely tiny changes in heart rhythm. The team found that the device can be used as part of a standard stress test to identify patients at risk. Then pacemaker-like devices can be implanted to regulate the rhythm disorder. "This technology has the potential to save hundreds of thousands of lives," says Cohen. "NASA can be proud." Such discoveries are no accident, says Michael E. DeBakey, a cardiovascular surgeon who has saved many hearts himself. "The key word is research. When I was a medical student and a patient came to the hospital with a heart attack, things were mostly a matter of chance. Today there’’s a better than 95 per cent chance of surviving. Now that all comes from research. The unfortunate thing is that there are people, even some scientists, who look at the money that goes to NASA and we could use the money to support our work. That’’s very short sighted. The more research that’’s done in any area of science, the better off everyone is going to be."
A．YB．NC．NG
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