Rockets for Research

Since the Second World War, and particularly the last fifteen years, a rapidly growing amount of effort has been devoted to the use of high-powered rockets to carry instruments up to great heights above the earth, to launch artificial satellites and deep space probes. We have pointed out how much has been and can still be done from the earth's surface. Why then all this concentration on use of rockets?

One of the main reasons is that our atmosphere while beneficial for life in general, prevents us from seeing the universe in any but a very restricted range of light -almost entirely confined to visible light and to a relatively restricted range of radio waves, in fact. We must take our observations from outside atmosphere to study the ultra-violet light, X-rays, infra-red waves and all those radio waves which cannot penetrate through our atmosphere. With instruments in artificial satellites circulating at heights of over 200 miles, such observations can be made. What they will record, we do not know - if we did, it would not be worth going to all this trouble - but there is scope here for astronomical studies for generations to come.

This is only one of the many major new possibilities for scientific research which are opened up by the development of rocket vehicles in the study of the earth's outer atmosphere, in the study of the space between the earth and the planets, and so on. There are four main categories of vehicles involved in this work, which has been called space research. First there are vertical sounding rockets which can go up to 1,000 miles or more, but are of most use below 200 miles. These rockets simply rise to the top of their trajectory and fall back to earth. Next, we have the artificial satellites revolving round the earth in elliptical paths, never penetrating closer than about 150 miles or so. A speed as high as 18,000 miles per hour, must be given to a body to launch it as a satellite. If the satellite orbit is very elongated, so that it passes out to distance several times the earth's radius (4,000), we have a deep space probe. The greater the launching speed, the greater the penetration into space before the return to earth. Eventually when the speed reaches 25,000 miles per hour, the probe never returns but becomes a satellite of the sun, an artificial planet. Probes may be specially directed to pass near any neighbouring planet, such as the recent moon probes and moon landings.

From the scientists' point of view, all vehicles play a valuable part. The value of any particular launching is the success of the experiment concluded, not just the distance reached from the earth. Nor is he concerned merely with manned space probes, for the instruments can be made to operate automatically and to send back their readings to earth - even over distances of millions of miles - as coded radio signals.