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Soyuz Spaceflights Become Routine

Medical monitoring of cosmonauts during the Soyuz program fo­ cused on assessing the physiological effects of microgravity. Cardio- respiratory measurements as well as extensive pre- and post-flight examinations were made of the central nervous system, metabo­ lism, blood chemistry, and fluid-electrolyte balance. The cosmo­nauts themselves became directly involved in the conduct of bio- medical experiments. A major setback was experienced with the flight of Soyuz 1, in which the cosmonaut died on impact when his vehicle's drogue parachute failed to deploy properly. When the Soyuz program resumed, following that catastrophic event, the early missions, lasting no longer than 5 days, revealed no unusual or unexpected physiological changes.

However, the flight of Soyuz 9 in 1970 gave rise to renewed con­ cern. This was an 18-day mission, far longer than any preceding it in either the Soviet or American programs. The two Soyuz 9 cosmo­ nauts exhibited pronounced orthostatic intolerance upon reentry and landing, and had to be carried from the space module on stretchers; they required 11 days of post flight re-adaptation to grav­ity. This event led to gloomy speculation that the limits of human endurance of space flight had been reached. However, the experi­ ence of Soyuz 9 prompted the appropriate response: major empha­ sis now developed on the use of countermeasures to space "decondi tioning" of physiological functions. Subsequent Soyuz missions demonstrated the effectiveness of exercise (using chest expanders, elastic straps, and isometric techniques) and a special "Penguin" suit which provides a constant loading on muscles of the legs and torso.

salyut: the space station era

The early 1970s was the beginning of the Salyut space station series. By then, confidence had increased that humans could toler­ ate missions of relatively long duration. The Salyut stations were intended for long-term habitation by rotating crews. In addition to basic life support systems, facilities were provided for eating, sleep­ ing, personal hygiene, and exercise. The crew of Soyuz 11, in 1971, the first to enter Salyut 1, conducted scientific experiments which included biomedical studies of the long-term response to micro- gravity. These cosmonauts also investigated exercise as a counter- measure; their 2.5 hours of exercise each day included walking and running on the treadmill with which the Salyut station was equipped. Biological specimens and a hydroponic "farm" for growing plants were on board. Tragically, the three-man Soyuz 11 crew died during reentry. This was the last time that a Soviet crew flew to or from space in "shirtsleeves"; all subsequent flights have required the wearing of a pressurized space suit.

Salyut 3, launched in 1974, had a more "homey" interior design and decor. Physical exercise as a countermeasure was again em­ phasized by the Soyuz crew that visited it. Medical experiments in­cluded studies of cerebral blood circulation and atrial blood veloci­ ty. On the next station, Salyut 4, the "Chibis" vacuum suit was worn, for the first time, during exercise and for extended periods during normal activity. This suit applies negative pressure to the lower body, simulating the pull of gravity on the circulatory system, and thereby helping to minimize cardiovascular decondi tioning. In addition, a rotating chair was installed for observing vestibular function. A bicycle ergometer ("veloergometer") was on­ board for performing exercise and measuring physiological param­ eters under stress. The last crew to visit Salyut 4 (Soyuz 18) tested a new cardiovascular countermeasure that combined exercise with a high-salt diet and forced intake of water to increase the body's fluid volume in preparation for landing.

By now Soviet space crews had been in space for as long as 63 days at a time. It had been clearly shown that a rigorous program of physical exercise, in combination with lower body negative pres­ sure (LBNP) and other countermeasures, could minimize the decon ditioning of the cardiovascular and muscle systems. Space motion sickness had proved to be merely an annoyance in the early phase of flight, and Soviet mission schedules were adjusted to compensate for this temporary disability. All other changes seen in space, such as red blood cell losses, seemed to be benign and to return to normal within two or three weeks post flight. The only spaceflight adaptive change that was still worrisome, from the standpoint of near-Earth missions of this length, was the apparently progressive loss of calcium from bone.

The second generation space stations, beginning with Salyut 6, allowed longer periods of occupation. A system for regenerating water supplied crew members with wash water, and a shower was now installed. The station was fully outfitted to support what was one of its major objectives: testing the limits of human endurance of space flight. Five long-duration primary crews carried out mis­ sions to Salyut 6 lasting 96, 140, 175, 185, and 75 days. Each of the prime crews was periodically visited by short-term crews who con­ ducted experiments separately and jointly. Often, the visiting crews studied the acute phase of adaptation to microgravity; they also served as experimental controls to the prime crews. A comprehen­ sive program of psychological support was implemented, emphasiz­ ing frequent, varied, and highly diverting contact with a wide range of people on the ground, as well as onboard entertainment. The sleep/work schedule was carefully designed and adjusted by space psychologists on the ground.

Salyut 6 crews continued the biomedical investigation carried out by their predecessors in space. They also conducted an extensive and increasingly sophisticated series of biological experiments uti­ lizing plants and animals, fish, and insects. Especially interesting were those experiments in which "space greenhouses" were main­ tained. These were small-scale ecosystems that permitted study of the interactions of various biological organisms and systems in the microgravity environment. They included many types of plants, growing on a variety of nutrient-rich substrates. These experi­ ments, still continuing, are directed at the development of biologi­ cally regenerable life support systems that can recycle human wastes and carbon dioxide, producing oxygen, potable water, and food.

In 1982, Salyut 7 was placed in orbit. Biomedical research contin­ ued along established lines in this station, which was itself closely similar to Salyut 6. Extension of human stay-time in space was still clearly the aim, and the first crew aboard set a new duration record of 211 days, performing hundreds of experiments. A visiting Soviet-French crew performed cardiovascular studies utilizing a French-made echocardiograph device, "Echograf". A subsequent prime crew, in 1983, set a new EVA record with virtually back-to- back spacewalks approximately three hours each.

SUPPORTING BIOLOGICAL RESEARCH

Even before the first space flights, the Soviet piloted space pro­ gram had been supported by an extremely active and diverse pro­ gram of biomedical research, including both human and animal studies, as well as experiments on plants, tissues, cells, and mi­ crobes. Not only are experiments carried out onboard the space sta­ tions, but control experiments are conducted on the ground. These are often extensive and long-lasting, such as those in which human subjects are subjected to many months of bed-rest; in comparable bi­ ological studies, rats and other animals are immobilized by various means to examine the effects of reduced activity, or "hypodyna mia." Most impressive of all are the Soviet biosatellite missions, which may contain dozens of specimens representing several phyla of plants and animals, all monitored closely from the ground. Table 6 displays all Soviet space biological missions flown on automated spacecraft through 1983.

By the end of 1983, the Soviets had flown at least 16 dedicated biosatellites, on a schedule averaging roughly one every two years since the mid-1960s. The last biosatellite flown in this period, Cosmos 1514, represented a quantum advance in that it contained two rhesus monkeys, in addition to other animals and fish. The mission involved heavy participation by U.S. investigators; one of the monkeys was implanted with U.S.-made blood pressure and flow transducers, to support cardiovascular studies.

By means of this diverse program of medical and biological re­ search, in space and in laboratories on Earth, Soviet space medi­ cine specialists had demonstrated by the end of 1983 that humans can remain in space for periods of up to seven months without suf­ fering long-term ill effects; indeed, they often return to Earth in nearly as good condition as when they left. Longer missions continue to be mounted, as described in the following chapters. However, it was clear by the end of 1983 that the Soviets were beginning to gear their space life sciences effort increasingly toward very long-term missions beyond the protective environs of Earth. Efforts to understand and counteract the adaptive changes seen in the cardio­ vascular, musculoskeletal, and neurovestibular systems were con­ tinuing. But research on radiation effects and countermeasures, on bio-regenerable life support, and on crew psychological/sociological factors, were gaining in prominence. Representatives of the Soviet space program were increasingly making reference to plans for a piloted mission to Mars, sometime in the not-too-distant future.

conclusion

By the end of 1983, the Soviets had learned a great deal about orbital space stations and the performance of human crews. The tens of thousands of remote sensing images obtained with space- borne cameras and the hundreds of materials processing experi­ ments conducted from Soyuz 6 in 1969 through the end of 1983 proved to the Soviets that space experiments could have economic potential. The significant repairs conducted by crews on Salyut 5, 6 and 7 to enable the continued functioning of those space facilities showed the value of having repairmen on board. From Vostok 1 to Salyut 7, cosmonauts had evolved from passengers to integral par­ ticipants in spaceflight.

By extending the duration of spaceflight, the Soviets established a basis for assessing the risks of performing even longer flights, perhaps to other planets. They learned about the psychological as well as physiological hurdles that must be overcome. They also dis­ covered the logistical constraints that would be encountered in pro­ viding a crew with the consumables needed for a trip that could take 1.5 to 2 years. Frequent resupply missions with Progress will not be possible on an interplanetary voyage. The types of supplies, repair parts, tools, and so forth that will have to be taken along on a long journey away from Earth are better understood because of the Soviet space station missions. Although they were not able to send people to the Moon before the United States, and it must have been a bitter blow to them at the time, their "low-tech," plodding approach may appear more logical in a historical context than the "high-tech," but stop-and-go approach of the United States. While many talk today about the virtues of sending a joint U.S./Soviet crew to Mars instead of mounting a national effort, the Soviets are further ahead in understanding what would have to be done to un­ dertake a piloted mission to Mars. If the decision were made to make the first flight a national expedition, the Soviets are now in a better position than the United States to accomplish such a goal from the viewpoint of experience. 15

References:

1. SOVIET SPACE PROGRAMS: 1981-87, PILOTED SPACE ACTIVITIES, LAUNCH VEHICLES, LAUNCH SITES, AND TRACKING SUPPORT PREPARED AT THE REQUEST OF Hon. ERNEST F. HOLLINGS, Chairman, COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION, UNITED STATES SENATE, Part 1, MAY 1988, printed for the use of the Committee on Commerce, Science, and Transportation, U.S. GOVERNMENT PRINTING OFFICE, WASHINGTON, D.C. 1988,

15 It should be stressed, however, that the United States remains the leader in space technolo­ gy, another important ingredient in attempting to send crews to Mars.