Long Periods in Space Deeply Affect Body, Soviets Say

Prolonged weightlessness in space has a deep-rooted effect on the human physiological system, draining space travelers of energy and forcing vital organs such as the heart to work much harder, Soviet scientists reported here Tuesday.

The findings suggest that long-term operations in space are more difficult for humans than previously believed.

The scientists did not indicate if such physiological changes seriously threatened the cosmonauts’ capacity to perform or if the changes had a lasting effect.

The findings are based on studies of Soviet crews that have spent more than six months in space, thus offering scientists an extraordinary opportunity to examine human adaptability to long periods in near-zero gravity.

Fundamental Changes

The Soviets, who presented their findings at the International Aeronautical Federation Congress here, said prolonged weightlessness fundamentally changes the way muscles behave, and may actually cause subtle chemical changes within the body.

A. D. Egorov of the Institute of Biomedical Problems of the Soviet Academy of Sciences said studies have shown a “decline of muscle performance” because of a “reduction in the body’s energy supply system.” That apparently is the result of a less efficient cardiovascular system that is robbed of some of the hydrostatic pressures normally used to help force oxygen-carrying blood throughout the body, he said. Other factors include changes in muscle tone “that makes the flow of the blood inefficient,” Egorov said.

“The human body needs time to adjust,” he said, suggesting that even the extended assignments aboard the space station may not be long enough for the body to adapt fully.

American Experiences

The Soviet findings are consistent with reports from American astronauts who have been required to perform rigorous activities in space.

Several astronauts have said that they tired much more quickly in space, and that even simple chores required far more energy than they had expected.

In addition, about half of those who have flown aboard American spacecraft have suffered from “space sickness” during the first few days of flight, a debilitating though temporary illness that is much like seasickness.

And on Tuesday, Charles M. Oman of the Massachusetts Institute of Technology presented the results of extensive research on space sickness among U.S. crewmen. He said it is caused by a totally different set of problems than those confronting long-term space travelers.

Oman said space sickness seems to be more the result of disorientation than fundamental physiological changes.

The Earth Above

Oman was responsible for a series of experiments on the first flight of Spacelab two years ago, and he said those experiments showed that “simply looking out the window and seeing the Earth above instead of below has been associated with episodes of vomiting.” That was particularly true for pilots, he said, who have been trained to expect to see the Earth below their craft, not above it.

Other causes include suddenly seeing another member of the crew upside down, or even moving the head too quickly in any direction.

Oman’s experiments included the use of motion sickness drugs, but he said the results did not indicate that the drugs were particularly helpful. One reason for that is that drugs simply “seem to be less effective in space,” he said, possibly because they take much longer to take effect.

While space sickness has been regarded more as an annoyance than a serious affliction, Oman said it clearly has an effect on crew performance.

“It affects crew efficiency,” he said, “and it affects their motivation. But I don’t think it affects their ability to respond to emergencies.”

By the fifth or sixth day of the flight, he added, the threat of space sickness has been reduced to the point that “even brisk movements of the head do not elicit symptoms.”