Plans For Manned Orbiting Space Station

Press, Volume CII, Issue 30154, 11 June 1963, Page 7

Plans For Manned Orbiting Space Station

A correspondent, who signs himself as ‘“Simply Curious," wants a simple explanation of the artificial gravity which will be provided for the crews of future manned orbiting space stations. This is a timely topic since it is expected that the American Aeronautics and Space Administration will announce a full-scale MOSS • Manned Orbiting Space Station > programme before the end of this year Already bids for a prototype MOSS have been invited and received from 18 major aerospace firms. The MOSS concepts fall into two categories—those providing artificial gravity to combat weightlessness- in space and those without such provisaoc. Judging by the comments of the American astronauts they enjoy the state of weightlessness but the long duration orbital flights by both Americans and Russians have produced medical sympt >ms which may be caused by lack of gravity. If so. some form of artificial gravity will be vital in manned space

stations, but it is still too early to be positive. The forthcoming long-duration fl ghts of Project Gemini are expected to settle the question. If required, artificial gravity may be produced by giving a space station a small amount of rotation. A space station 200 feet in diameter needs to rotate at only one. revolution every 15 seconds in order to provide the occupants with a sensation of gravity equivalent to that which we experience on the surface of the eafth. Such a station might be shaped I ke a wheel or huge inflated tyre, as in the illustration. or be more like a dumb-bell or a Y with compartments a t each of the three ends. Any shape will do. provided that the living compartments are well removed from the centre of rotation. N’ow for an explanation of the artificial gravity effect Any schoolboy who' has whirled a billy-can of milk over his head without spilling any knows about it. To improve our understanding let us imagine a stone in a small bucket with a long s ring tied to the handle. If the end of the string is held and the bucket is whirled around one’s head the stone within the bucket travels the same circular course as the bucket. If the stone were able at any instant, to free •self from the bucket it would fly off at a -tangent to the circle and follow a s’raight course. This straight line motion is the natural state of affairs, but the bucket and string supply a force which deflects the stone

away from a straight path into a circular path. The stone reacts to this force and presses down hard on the bottom of the bucket. This is exactly as if the action of a gravity force, directed so that “outwards” takes the place of “downwards.” is keeping the stone in the bucket.

The astronauts in a rotating space station react in exactly

the same way as the stone in the whirling bucket. To them the inside surface of the outer rim of the station is the “floor.” They walk upright on it exactly as on the surface of the earth. It would seem to be an inside-out sort of world because the hub of the space station would always be upwards, in contrast to our situation where the centre of the earth is downwards no matter where we are.

If an astronaut climbed a ladder to the hub he would find himself in a state of weightlessness—a convenient feature for certain experiments Attached by bearings at the hub would be any nonrotating sections of the station, such as docking facilities. radio antennae and telescopes for viewing the earth or stars.

The amount of artificial gravity which can be produced "in a space station depends on both the size of the station and the speed of rotation. For a given amount of “gravity” at the rim, the smaller the station the faster it needs to rotate. Most researchers feel that the human tolerance for continuous rotation has an upper limit of four revolutions «per minute If we take a gravitational effect equal to half that at

the earth's surface as being adequate, this leads to a minimum space station diameter of 200 feet, which makes it quite a large structure to erect in space. Some aerospace firms favour construc-

tion of the station in modular sections, .boosted into space separately and joined together after rendezvous in the ’final orbit. Other firms prefer different methods, such as the Goodyear Aircraft Corporation's inflatable space station illustrated on this page. Scientists of the Grumman Corporation believe that human beings can tolerate as much as 8 r.p.m for long periods without becoming nauseated. If so. the diameter of a space station can be reduced to 50 feet, making it much easier to establish in orbit. A 50-foot MOSS project would be feasible in only two or three years' time by making use of the Saturn C-l rocket now being tested, or the forthcoming Titan HI rocket. Either of these large boosters could launch the station into a circular orbit at an altitude of 300 to 500 miles—if any lower, the effects of the airdrag would reduce the lifetime of the station too much and if higher the crew would be exposed to excessive radiation dosage from the Van Allen belts surrounding the earth

The Russians also have plans for orbit’ng manned space stations in the near future. In a recent issue of a Czechoslovakian technical journal there appeared an article by Z. Dobrichovsky entitled “Astronomical Observatory in Space.” This

describes a space station. 35 feet long, without provision for artificial gravity. It would orbit at 500 miles altitude and its four-man crew would remain in space for 60-day shifts, using the empty fuel tank in the launch rocket as living quarters. The control compartment is in the detachable nose which has its own small rocket motor tor emergency return to earth. The observational equipment is located between the control compartment and the living quarters. Dobrichovsky points out that the current Soviet programme of satellite launchings is providing the know-how essential for the construction of orbiting space observatories. He claims that under this programme orbiting observatories could be a reality by 1966.

The Americans tend to believe that MOSS projects should follow after they establish a foothold on the moon. If Dobrichovsky is correct in his forecast a Soviet space station programme ’ may force the Americans to give higher priority to their MOSS programme. If two Russian cosmonauts should successfully rendezvous their capsules inspace this year the first step will have been taken.