The Hazards of Orbital Flight

By Anastasia Toufexis

Nausea, fatigue, higher pulse rates are a few of the dangers

The space shuttle Challenger, its maiden flight twice rescheduled, sat on its Florida pad last week plagued by glitches. Gas leaks had been discovered in both an original engine and its replacement. But for the next group of astronauts, mechanical foul-ups are only one worry. Today's space travelers have an additional concern: the body's reactions to zero gravity.

U.S. Astronauts Bill Lenoir and Bob Overmyer experienced nausea and vomiting during the fifth flight of the Columbia last November. Lenoir's distress helped force changes in planned space tasks during the five-day mission. Space sickness, renamed by NASA "space adaptation syndrome" (SAS), was recognized only a decade ago. Says former Astronaut Mike Collins: "We didn't have much of a problem with space sickness as long as we were strapped in Mercury and Gemini. Same for the Russians. It's when we all began floating around in Skylab and the Russians in Salyut that the guys began getting sick."

Between 30% and 50% of space voyagers develop SAS, usually in the initial days of a flight. It is not yet possible to determine who is susceptible. Scientists believe the malady is caused by the body's struggle to adapt to the absence of gravity and to disorienting shifts in body positions. As a result the brain receives conflicting information from the eyes and the inner-ear system, which registers pressure changes and affects balance. Says Dr. Philip Johnson, chief of the medical-research branch of the Johnson Space Center in Houston: "In space you receive a lot of novel input into the brain, which doesn't know how to handle it. We just have to adapt. Some people adapt rapidly, some slowly. It's like going out on a boat with a lot of people. Some will get sick and others will be just fine."

NASA is pressing for a cure because SAS can disrupt short-term flights. As a temporary remedy, astronauts routinely take along pills containing a combination of scopolamine, a drug that blunts sensations, and dextroamphetamine, a stimulant to counteract scopolamine's dulling effects on the body and mind. When the pills failed to help Lenoir, NASA's chief flight surgeon Sam Pool advised from Houston ground headquarters that Lenoir also take Phenergan, an antihistamine, and Dalmane if he needed a sleep medication. But the combination of potent drugs is not an ideal solution since it can impair coordination and judgment. According to an Air Force surgeon at Andrews Air Force Base, any military or commercial pilot on such medication would automatically be grounded. Says he: "Before you fly, that stuff has got to wash out of your system." To learn more about SAS, NASA will be sending physician-astronauts on the next three shuttle flights. They will study the relationship between the eyes and inner-ear system, and the effects on the body of inertia and weightlessness.

SAS is a minor irritation, however, compared with the hazards of long-term space flights. U.S.S.R. Cosmonauts Anatoli Berezovoy and Valentin Lebedev returned last December from their record-breaking 211-day flight in obviously debilitated condition. Soviet TV clips showed the cosmonauts being helped into a hot whirlpool bath. Even though they had exercised daily, the prolonged weightlessness left their muscles so flabby that for a week they were barely able to walk. Five weeks after the landing, TASS, the Soviet news agency, reported that they were in the Caucasus continuing "to undergo rehabilitation."

Muscle atrophy is a visible effect of long space flights, but there are less obvious dangers. All are related to lengthy stays in zero gravity, though scientists do not fully understand why all the changes occur. Bones lose lose one-half of 1% of their calcium each month. Some body fluid shifts from the extremities to the chest and head; a portion of the fluid is excreted. Fatigue sets in, and sound sleep becomes elusive. The heart's size shrinks by 10%. Astronauts exercising on land after a flight have a higher pulse rate than they did before space. "We think it takes only 48 hours in space for this change in the heart to take place," says NASA's Johnson. The heart apparently returns to normal within a year of returning to earth.

In the Soviet Union, the Berezovoy-Lebedev mission has sparked a rare public debate over one major question: How long can a person stay aloft before suffering irremediable harm? Cosmonaut Valeri Ryumin, who had set earlier flight records by orbiting the earth for 175 and 185 days, believes the safe limit has been breached. Says Ryumin, now a senior program chief at the Soviet space control center outside Moscow: "It appears to me that four months is the optimal period."

Soviet officials, however, are unlikely to agree. One goal of their space program is to build an orbital platform for military and scientific ventures. Lacking a reusable space shuttle like Challenger to ferry men and material, the Soviets have been forced to send their crews up for longer and longer periods. Declares Anatoli Alexandrov, president of the U.S.S.R. Academy of Sciences: "The strategy of a gradual increase in man's stay in space has justified itself completely. It means that even longer space expeditions are quite feasible."

--By Anastasia Toufexis. Reported by Erik Amfitheatrof/Moscow and Jerry Hannifin/Washington

With reporting by Erik Amfitheatrof/Moscow, Jerry Hannifin/Washington This file is automatically generated by a robot program, so viewer discretion is required.