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  3. Surviving In Space Motion sickness afflicts more t

Surviving In Space Motion sickness afflicts more t

游客2024-02-24  50
问题                           Surviving In Space
    Motion sickness afflicts 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 of gravity information, a confused brain engenders visual illusions.  Sensing too much fluid, the body begins to excrete it, including calcium, electrolytes and blood plasma. The production of red blood cells decreases, rending astronauts slightly anaemic. With the loss of fluid, legs shrink. Spinal discs expand, and so does the astronaut--who may gain five centimeters and suffer backache.  Though the process may sound terrible, astronauts adjust to it, 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 tainting, needing to be carried from the spacecraft. "We are creature 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 Gohtin established the National Space Biomedical Research Institute ( NSBRI), a consortium of experts from a dozen leading universities and research institutes. NSBRI will study biomedical problems and by 2010 will present NASA with a "go" or "no go" recommendation on a Mars mission.
    Jeffery Sutton, leader of the medical systems team at the NSBRI, has treated tile head trauma, wounds, kidney stones and heart rhythm irregularities that one could encounter on the way to Mars. On the spacecraft he envisions, Mars-bound in the year, say, 2018, there may lurk harmful bacteria or carbon monoxide. No problem. The deadly substances will be detected by smart sensors--micro-processors  no bigger than a thumbnail--that roam autonomously 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 tissue right now.
    Lying in wait beyond the earth’s atmosphere, solar radiation poses additional problems. Coronal mass ejections fling billions of tone of electrically charged gas into space, relegating the earth’s volcanic eruptions to mere hiccups. Nevertheless, NASA officials are confident that accurate monitoring will warn astronauts of such events, allowing the crew to take refuge in an area where polyethylene 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 Cucinotta, manager of NASA’s Johnson Space Centre. "They pass through tissue, striking cells 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 Mars7 "Yes, we will, perhaps  even before. We’re very confident," says Laurence Young, the director of NSBRI. Meanwhile some of NSBRI research 4way bear fruit on the 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 disturbance called ventricular fibrillation. This kills 225,000 people in the US each year.
    Richard Cohen, head of the NBSRI cardiovascular team, explained that zero gravity may--emphasizing "may "--incite this condition in astronauts. So the team invented a non-invasive 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 anomalies. "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. DeBackey, 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 people, even some scientists, who look at the money that goes to NASA and say we could use that money to support our work. That’s very short-sighted. The more research that’s done in any area of science, the better off everything is going to be." [br] Each year, 22,000 cardiacs in the US died of___________.
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答案 ventricular fibrillation
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