10. THE SCIENTIFIC EXPLORATION OF SPACE

By Sir Harrie Massey

(from a television talk in a series arranged by Granada TV)

Since the war, and particularly during the last few years, a rapidly growing amount of effort has been devoted to the use of high-power 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 the 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 make observations from outside the atmosphere to study the ultra-violet light, X-rays, infra-red rays 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 meteorology, in the study of the space between the earth and the planets, and so on. There are four categories of vehicles involved in this work, which has been called space research. First, there are vertical sounding rockets which can go up to l,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 distances several times the earth's radius (4,000 miles), 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 the moon, or hit the moon or become satellites of the moon. These are the lunar probes of which there have been a number of examples recently.

From the scientist's point of view, all these vehicles play a valuable part. The availability of artificial satellites does not make vertical sounding rockets obsolete and this is even more true of deep space and lunar probes in relation to artificial satellites. To the scientist 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 with putting men in the vehicle, 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.

(from Discovery, published for Granada TV by Methuen, London, 1961)