September 10 1963 - Bases on the Moon

Twenty years ago the idea of practical space research was widely regarded as a wild dream, and members of Interplanetary Societies were dismissed as cranks. Events have shown that the 'cranks' were right.

The concept of a communications satellite was first put forward in 1943 by Arthur Clarke, who is known both as a theoretical astronaut and as a particularly skilled writer of science fiction (to say nothing of his activities in underwater photography). Arthur Clarke, whom I have known well for a great many years, now lives in Ceylon. During his brief visit to England in October 19631 was delighted that he was able to join me in a programme. Bravely, he ended by making some forecasts about what was likely to happen in the future; it will be interesting to see whether he was as accurate as he was in the 1930's.

Official statements have made it clear that the Americans, at least, plan to put a man on the Moon as soon as possible. Though there have been recent indications that the Russians are more interested in elaborate orbital vehicles and automatic probes rather than manned lunar flight, there can be little doubt that the Moon will be reached in the foreseeable future.

The progress of space research during the last two decades has been amazingly rapid. Thirty years ago the whole concept of interplanetary travel was widely ridiculed, and from a scientific point of view the rocket was regarded as little more than a toy. The situation was altered with dramatic suddenness by the advent of the German A4 vehicle, better remembered as the V2, which, although purely a weapon of war, was the basic ancestor of future space-probes. It was extremely fortunate for civilization that the Germans were not able to bring their rockets into action at an earlier stage.

It did not take long for the more peaceful potentialities of rocketry to become evident. In particular, the concept of a communications satellite dates from October 1945, when Arthur Clarke published his now-famous article 'Extra-Terrestrial Relays' in the British journal Wireless World. In this paper Clarke laid down the fundamental principles of communications satellites, and it is appropriate that he should have been awarded the 1963 Stuart Ballantine Gold Medal by the Franklin Institute of Philadelphia. The citation states that the award has been made for 'his soundly based and prophetic early concept of the application of satellites­ in the primary human endeavour of communication'. The draw­ings used to illustrate this paper have a strangely modern look about them, even though they were originally drawn eighteen years ago and were then regarded as hopelessly futuristic.

The real change in public opinion came in 1957, when the Russians launched the first artificial satellite. Two years later they managed to land a small vehicle on the surface of the Moon, and the idea of a lunar base became officially 'respectable'. One result was that lunar observation, formerly an amateur field, began to receive a certain amount of attention from professional astrono­mers. By now we have a sound knowledge of the topography of the areas of the Moon observable from Earth. The reverse side of the Moon seems to be of the same general type, and the chart produced by Y. N. Lipski on the basis of the Lunik photographs is probably accurate in the main. It has been said that our knowledge of the topography of the Moon is greater than our knowledge of central Greenland or Antarctica.

On the other hand, there are still many important problems awaiting solution. Authorities are not agreed as to whether the craters of the Moon are volcanic, or whether they were formed by meteoric impact; it seems that both mechanisms must have operated, and it also seems that a little mild activity lingers on here and there, since N. A. Kozirev has reported gaseous emissions from the craters Alphonsus and Aristarchus. * More important from the space-research point of view is the question of a possible dusty or ashy layer.

There is no strong local colour on the Moon, and the albedo or reflecting power is very low - in the region of 7 per cent, as against over 60 per cent for the cloud-covered planet Venus. It has often been maintained that the entire Moon is coated with a mixture of volcanic ash and meteoritic dust; and in 1955 T. Gold suggested that the broad dark plains, still miscalled 'seas' (maria), were likely to be covered with a layer several kilometres deep. If so, he con­sidered that 'space travellers of the future will simply sink into the dust with their gear'.

On Gold's theory the dusty particles are very small, so that the various thermal and electrical effects will cause the surface to become agitated and to behave rather in the manner of a liquid. Wherever the dust is formed, it will flow downhill to the lowest point, and will therefore collect in the relatively low-lying maria to form tremendous drifts.

* In late 1963, red patches near Aristarchus were seen by J. Greenacre and his colleagues at the Lowell Observatory. Incidentally, at a major lunar con­ference held in New York in May 1964, at which I was invited to read a paper, I found that the general view had swung back to the volcanic theory of crater origin.

If this idea were valid, the idea of a manned lunar base would have to be drastically revised. However, the suggested dust-drifts are not supported by many lunar specialists, and the weight of available evidence seems to be definitely against the whole theory. It is generally believed that any ashy or dusty layer will not be more than a few inches deep, and that solid rock lies underneath. If so, the surface should be well able to support the weight of even a massive rocket, but it is quite possible that there will be various unsafe areas, and the greatest caution will be necessary. Further landings of unmanned vehicles will certainly have to be carried out before the first manned expedition can be dispatched.

Our knowledge of 'local conditions' on the Moon is depressingly meagre, but at least a few general remarks may be made. Because of the lack of atmosphere, temperature conditions there are un­pleasant; there is no air to screen the surface during the long day, and nothing to blanket in the Sun's heat during the equally long night. At noon on the equator the temperature will rise to more than +210 degrees F, whereas at midnight a thermometer would register about —250 degrees F. Indeed, very recent results indicate that the minimum temperature may be lower even than this.

It is impossible to avoid the night-time cold, though fortunately the first lunar voyages will be relatively brief affairs, carried through in less than two Earth weeks or one lunar day. On the other hand, the intense noon heat may be avoided if the expedition lands well away from the equator. An early suggestion for a site was made by Wernher von Braun, one of the V2 researchers, who favoured the Sinus Roris, in the northern hemisphere. More recently the vast Mare Imbrium (Sea of Rains) has been con­sidered, and it was here, not far from the fifty-mile crater Archi­medes, that the Soviet probe Lunik II seems to have landed in September 1959. However, it is premature to come to any definite conclusions as yet. *

[1] In 1964 Ranger VI landed in the Mare Tranquillitatis, and Ranger VII in the Mare Nubium. The photographs from Ranger VII seem to give the coup de grace to Gold's dust theory.

Early concepts of a manned lunar base involved a series of surface domes, each equipped with its own system of air-locks. Bases of this sort were being advocated more than twenty years ago, and it is interesting to recall a drawing made before 1950 by the late R. A. Smith, a British pioneer of space-research theory. The domes, wireless installations, and other pieces of equipment are shown, together with provision for farming without soil. Though a lunar base cannot hope to be entirely self-supporting, it will be essential to make it as independent as possible, since ferrying supplies from Earth will be a difficult and costly business.

When Smith's drawing is compared with modern designs pro­duced in the United States, it will be seen that there are no funda­mental differences. On the other hand, it is possible that a surface base will prove to be impracticable, and that the station will have to be constructed underground. This is because the Moon is virtually devoid of atmosphere, and is unprotected from radiation and meteoric bombardment.

The low escape velocity (one and a half miles a second) means that a dense atmosphere cannot be expected, but in 1953 Y. N. Lipski, of Russia, announced that by indirect methods he had detected an atmosphere with a ground density of about 1/10,000 of that of the Earth. Negligible though this may seem, such an atmosphere would be quite efficient as a protection against small meteoritic particles. Unfortunately, later work has not confirmed Lipski's estimate; the real atmospheric density is much less, and as a meteor screen the lunar mantle is likely to be useless. The full extent of the danger is still not known, and so it is still impossible to say whether surface domes will be practicable.

The lack of atmosphere means that there will be no radio- reflecting layers surrounding the Moon; wireless range will be limited to the distance of the horizon, which will be most incon­venient. One solution will be to route longer messages by way of the Earth, but this will be far from easy, and will not be possible on the Moon's reverse side, from which the Earth can never be seen. In May 1962 I suggested that it might be practicable t provide the Moon with an artificial ionosphere in the form of a belt of copper needles, similar to those used in the regrettable US West Ford experiments.* The idea was supported by Z. Kopal and others, but it may well be that a chain of communications satellites will prove to be a better solution in the end.

Let us now return to the old question whether a lunar base is worth establishing at all. It is true that automatic probes can carry out vital scientific research, and it has been held that an unmanned base on the Moon will be just as valuable as a manned station. On the other hand, Arthur Clarke has stressed that com­plicated instruments are only too likely to give trouble sooner or later, and they have to be maintained and repaired - which can be done only by human agency. If one small component of an elaborate piece of mechanism proves to be faulty, the whole instal­lation becomes useless, even if the repair would be a ten-minutes' operation by a skilled maintenance engineer actually on the spot.

The uses of a lunar base would be many. Physical and medical laboratories on the Moon would be invaluable, and there would also be observatories, optical and radio. On Earth, optical astronomers are badly hampered by the Earth's dirty and unsteady atmosphere, so that it is seldom that a large telescope may be used to its full capacity; radio astronomers have begun to experience serious trouble from electrical interference. Both these hazards would be avoided on the Moon, which would be an ideal observa­tory site. Another pioneer suggestion was that of using the Moon as a launching base for vehicles bound for Venus and Mars, and this, too, may prove to be valid. The establishment of a manned lunar base is not imminent, and much research remains to be done. Further landings with automatic probes will have to be made. The American programme has fallen well behind schedule, and it seems certain that the Soviet Lunik IV of 1963 was also a failure. Circum-lunar journeys will also have to be carried out.

It is doubtful whether even the theorists of the nineteen-thirties thought that landing on the Moon would be achieved much before the end of the century, and events have taken place more quickly than seemed even remotely possible. At least the early pioneers were on the right track - and they could not foresee the outbreak of the war, which gave tremendous impetus to rocket research (albeit for the wrong reasons). It is therefore of interest to give some revised forecasts by Arthur Clarke, made in September 1962. They are as follows:

The first circum-lunar flight will be made in 1967.

The first lunar landing by a man will be achieved between 1970 and 1972, though there is a chance that it will come earlier - perhaps even in 1968.

The first flight round Mars will be made about 1980, and the landing there achieved by 1990.

A lunar base will be set up in 1975, and a base on Mars about 2000.

It may be said that these forecasts are highly optimistic - but this was also said about Clarke's forecasts of a quarter of a century ago, now fully vindicated. In any case, we may be sure that the developments of the next few years will be of the greatest interest and importance.