How Far the Moon?

Voyages to distant planets seemed blissfully easy a few years ago, because they were theoretical. Now that satellites, the first crude spaceships, are actually on orbit, spacemen are being asked to deliver real transportation, and a voyage even to the nearby moon looks disturbingly hard. The Astronautics Symposium sponsored in Denver last week by the Air Force and the Institute of the Aeronautical Sciences heard more about the staggering difficulties of space flight than about its rosy prospects.

One of the romantic notions withered by reality is that of human space explorers who will sail out into the solar system like Columbus into the Western Ocean. The day of these heroes may come, but most of the scientists who spoke at Denver think it will not come soon. The present job, they said, is to gather scientific information, and this can be accomplished better by expendable instruments than by fragile, weighty humans. Some of their opinions and projects:

P: A tremendous amount of work must be done before even one man can ride an earth satellite said Dr. William H. Pickering, director of the Army's Jet Propulsion Laboratory. A payload of several thousand pounds must be placed on orbit. The re-entry problem must be solved in a way that will give the human passenger a fair chance to survive. Many new instruments and gadgets must be developed. "Granted that we have done all these things," said Pickering, "it seems to me that we should now ask the question: 'What do we gain by placing a man in the vehicle?' " Pickering's answer: a satellite-borne human would be hardly more than a hitchhiker. A much smaller payload of instruments could make far better observations, transmitting the information by radio or sending pictures back to earth in some sort of armored capsule. "If a human passenger is a part of the data transmission system," said Pickering, "he will only, as the communications engineers say, add noise to the system and degrade the data."

P: With humans eliminated, the scientists agreed, a great deal of space exploration will be possible in a few years. Dr. J. Halcombe Laning Jr. of M.I.T. described an unmanned vehicle designed to photograph Mars. It would carry optical devices to observe the sun and the stars. It could watch Mars too, and steer toward it by means of small rockets. Swinging around Mars, it could take pictures through a camera showing objects 500 ft. long; then it would return to earth with its cargo of information. The whole vehicle, said Dr. Laning, need weigh only 300 Ibs. He thinks it could be tossed to Mars in about five to seven years from now, with no major technical breakthrough.

National prestige may make it important to shoot humans through space, but an actual landing on the moon or a planet is about the only mission for which a human crew would be a profitable payload. Some of the scientists at Denver thought that the first landings should be made by instruments to feel out the ground, but all agreed that only the alert and flexible human brain can do full justice to unexpected phenomena. Even on the nearby moon, the unexpected is to be expected. No one knows for sure what the actual surface is like.

P: The moon's flat maria (waterless "seas") are almost certainly covered with lava that poured out on the surface billions of years ago, said Astronomer Gerard Kuiper of Yerkes Observatory. In those days, Kuiper told the astronauts at Denver, the moon's interior was kept liquid by radioactivity, so any disturbance, such as a large meteor impact, was likely to cause an upwelling of lava. Kuiper thinks that smooth places on the maria will make firm landing spots for earth's spaceships.

P: Not so optimistic was Astronomer Thomas Gold of Harvard. Gold pointed out that the ring-shaped meteor craters on the moon can be given comparative ages by the way they overlap, and that the walls of the oldest ones are generally low. This means, said Gold, that during the 4 billion years or so of the moon's life, its exposed rock has been slowly turned into dust by bombardment of rays and particles from the sun and space. The dust, kept stirred up by the same agents that formed it, has flowed like a slow liquid into the moon's low places. So the maria, said Gold, are not filled with lava, but with dust, perhaps several miles deep. Gold suspects that the dust near the surface is still as fluffy as baby powder. He warned that an unwary spaceship that lands on a smooth lunar plain might disappear in dry quicksand.

P: Astronomer Fred Whipple of Harvard thinks that although the moon may have plenty of dust, its surface has been solidified. There may be a thin layer "like dust on a grand piano," but the underlying material, cemented together (not stirred up) by bombardment from space, is probably "crunchy" and strong enough to support an alighting spaceship.

P: Before a large manned spaceship tries to land on the moon, said Dr. John Barnes of U.C.L.A., it might be a good idea to test the treacherous surface from a safe distance. A nuclear bomb exploded on the moon would tell a good deal, but its radioactivity would contaminate the virgin surface. Dr. Barnes suggests that a small amount of chemical explosive would be enough. Once planted on the moon, it could be exploded by a signal from a moon satellite. The same satellite could capture tossed-up debris, and tell by examining it whether that part of the moon is a safe landing place.

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