Artificial Gravity In Space Stations

Press, Volume CIX, Issue 32142, 11 November 1969, Page 7

Artificial Gravity In Space Stations

The post-mortem on the death of the space-monkey Bonney has led to many queries concerning the wisdom of plans for long spaceflight* by man. Bonney died shortly after returning from 8f days in Earth-orbit last July. The flight was terminated much earlier than planned because telemetered bio-medical data indicated a rapid deterioration in the condition of the little pig-tail monkey. He—Bonney was a male monkey—died from a series of upsets in his body functions which ultimately stemmed from prolonged weightlessness, according to Dr W. R. Adey, a scientist employed by the National Aeronautics and Space Administration. Dr Adey points out that astronauts have suffered mild forms of the same body disorders which killed Bonney and has stressed that long manned spaceflights should be viewed with caution until more experiments have been undertaken with animals in space. This is, of course, simply common-sense prudence, but the death of Bonney does not necessarily prove that prolonged spaceflight will be lethal. Bonney's 8f days is barely more than half the period spent weightless in space by the crew of Gemini 7, Astronauts Borman and Lovell, who returned to Earth in fine shape, and only one-third of the time spent in orbit by the Soviet canine cosmonauts Veterok and Ugolyok. These two small black dogs not only endured 22 days of weightlessness but their orbit carried them repeatedly into the radiation belts surrounding the Earth. Upon their return it was discovered that their muscles had weakened, their bones had lost calcium and they had difficulty walking. Only ten days later they were fully recovered from their space ordeal.

Isolation And Fear Why, then, did Bonney succumb after a much briefer exposure to the space environment? It does seem possible that the real cause of the decline in Bonney's condition has not yet been traced. Perhaps the combi-

nation of isolation and fear had something to do with it. The Gemini astronauts and the Russian space dogs were orbited in pairs, providing companionship. But Bonney was a solitary monkey, and most monkeys are gregarious, arboreal creatures. The physical sensation of endlessly falling plus the utter loneliness may have induced a psychosomatic reaction which worsened the physiological effects of Bonney’s spaceflight The lesson to be learnt from the loss of the little monkey may well be that companionship is the most important ingredient for success on a lengthy voyage under weightless conditions. Notwithstanding these arguments it is already perfectly clear that some form of artificial gravity should be provided for the crew of any spacecraft designed for missions of long duration. For extended operations in Earthorbit the traditional wheelshaped space station design at least provides an artificial gravity force by virtue of its continuous rotation. All loose objects inside the rotating station appear to drift outwards until constrained by the rim to travel with it in a circular motion. As a result they then experience the sensation of a centrifugal force which has the same effect as gravity in holding them down on the inner surface of the rim. Rotation Important For this kind of artificial gravity it is not necessary for the space station to be shaped like a wheel. It is the rotation which is important. A space station consisting of two or more units interconnected by cable and rotating like a bolas would provide an artificial gravity just as effectively. This technique was used for the first time by Gemini 11 in 1966. On his spacewalk, Astronaut Richard Gordon tied a tether to the Agena target vehicle which had earlier made a rendezvous with Gemini 11. When Gordon was safely back Inside, the command pilot, Pete Conrad, undocked the Gemini from the Agena and backed slowly away. When the line was taut he fired his thrusters sideways to rotate the system at about one-third of a revolution a minute. This created an artificial gravity about onethousandth as strong as Earth gravity. Early space stations will overcome the gravity problem by restricting the tour of duty of every crew member, but sooner or later artificial gravity will be employed. Before discussing the likely layout of a future permanent space station, its essential purpose must be defined more clearly. In the past few years a great deal has been learned about the role of man in space and two things stand out very clearly. In any satellite of reasonable size intended for observing the Earth, Sun or stars at high magnification, the presence of man is a distinct nuisance. Just the breathing of an astronaut causes the observed image to swing to and fro in the field of view, while one good sneeze is enough to jerk an orbiting telescope right off target. On the other hand, an astronaut who is on the spot can make adjustments and mend faults to an extent impossible from the ground. Man Not Essential In 1966 the first orbiting astronomical observatory became useless on its second day in orbit when a fault in a battery regulator circuit deprived it of power. A technically trained astronaut on hand could have revived the spacecraft—and saved s7om. While there is no substitute for a skilled technician in space to service and make modifications to complex instruments, it is not essential for observers to be present in the space station, This is because modern data transmission and remote control techniques have advanced to the point where an observer on the ground can operate spaceborne instruments just as readily as if he was in space with them. With these considerations in mind we can attempt to visualise the form that a future space observatory might take. The various observing sections will be separate, circling the Earth in their own orbits, but keeping about half a mile from the manned section which rotates to provide artificial gravity. The manned section has a non-rotating hub where supply shuttles from Earth and inter-unit space taxis can dock. These taxi vehicles provide transportation to and from the observing units whenever servicing is needed. The observing units employ arrays of solar cells to provide power, but the much greater power demands of the manned section , are best, met by a zircbnium-hydride reactor and thermoelectric converter. This power plant is attached by a long cable to act as a counterweight for the rotating section of the station. A laboratory for studies under zero-gravity conditions might well be

incorporated in the nonrotating hub section. A somewhat similar scheme would be suitable for a permanent TV broadcasting station capable of transmitting a choice of programmes directly to home receivers. Another likely role for a manned space station is an assembly site and launch platform for expeditions to the planets. Manned space stations are no further than two years away. Like everything else they will grow and expand their usefulness. There is no shortage of suggestions for future stations in space. They range from holiday resorts and hospitals for weightless therapy, all the way to factories for exotic manufacturing processes which require an absence ,of gravity. Any other ideas?