SPACE PROGRESS The Man In Space Programme

Press, Volume XCIX, Issue 29278, 9 August 1960, Page 20

SPACE PROGRESS The Man In Space Programme

[Specially written tor "The Press" by

COLIN S. L. KEAY,

Physics

Dept., University of Canterbury]

In this column each month readers' questions regarding satellites and space exploration will, if possible, he answered. Questions should he sent to the address at the top of this column, or to the Space Progress Column, c/o. “The Press.”

A new era in the history of flight will be ushered in towards the end of this year when one of the seven American astronauts is carried aloft by a Redstone rocket. There is, of course, the real possibility that the Russians may be the first to send a man into space, but what we don’t know about we cannot discuss. The American time-table for space-flight on the other hand is the only one that is not shrouded in complete secrecy. The American programme for manned space-flight has been given the title Project Mercury. It is well advanced, with many of the essential preliminary tests successfully completed. During last September, for example, a full scale model of the mancarrying capsule was boosted by an Atlas rocket to a near orbital speed with gratifying results. It proved to be stable and successfully withstood the fierce conditions of re-entry into the earth’s atmosphere. The force of deceleration and the interior temperatures were within the range of human tolerance and the capsule was recovered safely from the Atlantic Ocean north of Puerto Rico.

At the end of last month an attempt to place a capsule in orbit failed owing to an explosion in the Atlas rocket when its twin booster motors were released. The failure was not in the capsule system. Although abortive, this latest test highlights the advanced state of the American programme. Further Test Flights The next major step forward will be taken when a 30-ton Redstone rocket carries a one-ton Mercury test capsule to an altitude of 125 miles and to a distance of 200 miles from Cape Canaveral. The entire flight from takeoff at Cape Canaveral to the parachute landing in the sea 200 miles away will take dnly about 16 minutes. This test is referred to as a ballistic flight because the flight path or trajectory will be very similar to that followed by a shell fired from a gun. For the first Redstone-boosted ballistic flight the capsule will only contain instruments to record its performance under the loads of launching and re-entry. These loads will not be as severe as those encountered during a full orbital test but they are still extreme by ordinary standards. Later on, if these early tests prove satisfactory, a capsule containing a chimpanzee will be flown along the same trajectory, setting the stage for the first ballistic flight into space by an American astronaut.

During his 16 minute flight the astronaut will be accelerated to a speed of 4000 miles an hour and in reaching that speed he will need to withstand the effect of weighing six times his normal weight. On • re-entering the atmosphere his weight will seem to rise to 11 times normal, or almost a ton. But between these phases of the flight he will experience complete weightlessness for about five minutes, some five times the period that has hitherto been experienced. Throughout the launching and re-entry the astronaut has also to be protected from the severe effects of heating and noise. For these reasons the capsule design has stretched available engineering techniques to the limit. The Manned Capsule

The accompanying illustration shows one of the seven American astronauts, clad in his special pressure suit (not quite a spacesuit), about to climb through the entrance hatch into a fullscale model of the Mercury capsule. The three large bags attached at the top of the capsule are inflated when it hits the water after the flight is over. They are to ! ensure that the capsule will float correctly. At the bottom of the capsule six rocket orifices can be seen. Three of them are for separating the capsule from the booster at the end of the launching phase. The other three will not be used for the ballistic flights but only for the later orbital missions. They are retrorockets intended to slow the capsule down sufficiently for it to lose orbital speed and re-enter the atmosphere. Heating and stability considerations during re-entry dictated the shape of the capsule proper. When it returns to the atmosphere the bottom blunt end will be facing forward and the heat

of re-entry will be dissipated by a plastic heat shield. However, the astronaut inside will be contained in a double walled pressure vessel made of titanium and specially insulated to give maximum heat protection. The rear portion (towards the top in the picture) which will be heated to a lesser extent, is made from a nickel alloy capable of dissipating the heat by radiation out into space. The insulation between the heat shielding material and the pressure vessel also serves as acoustical insulation for reducing the very high sound intensity from the booster rocket during the launching and the aerodynamic noise of re-entry, thereby making the flight more comfortable and saving the astronaut from permanent deafness.

Within the pressure-tight capsule the astronaut is supported in a form-fitting couch so that he can tolerate the great increase in his weight mentioned earlier. An environmental control system will maintain the cabin atmosphere within prescribed limits and a communication system will enable voice contact with ground stations to be maintained throughout the entire trip. Enough has been said to indicate that the capsule is far from being a simple vehicle. Its complexity is best appreciated from the fact that it contains seven miles of electrical wiring to control and link its many internal systems. Escape System

One of the most important requirements when manned flights are undertaken is that of providing a safe escape system to get the capsule and astronaut well clear if the launching rocket should explode. Even with such well-proven rockets as the Redstone and Atlas there is always the chance of failure of the rocket itself. Escape will be accomplished using a small auxiliary rocket mounted on a tower arrangement at the top end of the capsule. In the event of an impending failure, which can be sensed by suitable instrumentation, the escape system will be triggered. This fires the escape rocket which then pulls the capsule clear of the booster rocket at an additional speed of over 300 miles an hour. It will, in fact, put 250 feet between capsule and booster in the first second, which should be ample to get the capsule out of danger. If all goes w’ell and the escape system is not needed it is jettisoned as soon as the booster rocket is spent In the Project Mercury programme it is obvious that every conceivable contingency has been allowed for. The flights into space will be as safe as it is humanly. possible to make them. Of that the astronauts themselves are fully aware since they have been intimately associated with all phases of the development programme. One might ask what are the duties the astronaut would be expected to perform during his brief excursion into space. On later flights his duties will be very extensive, but for the first flight it will be next to nothing: the emphasis being solely on getting back safely. No doubt all that is expected of the first astronaut, be he Russian or American, is is that he should return fit enough to face the microphones and cameras and express with eloquence his impressions of spaceflight.