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Monmouth Message
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MONMOUTH — Scientists of the U. S. Army Signal Corps do not allow the
moon to spend its nights in idle glimmer. The earth's natural satellite. which nearly 15 years ago, bounced back the 1st man-made impulses to strike its crater-marked face, has proved to be a versatile electronic tool for the U.S. Army Signal Research and Development Laboratory. The Laboratory's Diana radar made the `first contact with the lunar body in January 1946. Scientists and engineers have been periodically pointing their antennas toward it ever since. As a result of such experiments, much information on how to communicate with space vehicles already was on hand when the U. S. started launching satellites nearly three years ago. STUDY Meantime, Dr. Fred B. Daniels, Little Silver and Dr. S. J. Bauer, Asbury Park, scientists in the Signal Laboratory's Institute for Exploratory Research, are making an intense study of the lunar terrain and the electron content of regions between the moon and the earth. More knowledge of the moon's surface will be valuable informa-tion when explorers make their first landing, says Dr. Daniels. Billions of years old, the moon is hammered by meteorites, which easily penetrate its thin atmosphere. It long ago reached a state of equilibrium: as small new craters, or craterlets, are formed, they are likely to erase old ones. Therefore, the character of the surface remains essentially the same, Dr. Daniels continues. He points out that the smallest crater, which can be seen with optical telescopes is about one thousand yards in diameter, whereas radar can be used to measure craterlets of extremely small size. DETAILS The fine-scale details of the lunar surface are being measured in accord with a new theory formulated by Dr. Daniels. The method was outlined in a recent issue of 'Nature,' the well known British scientific magazine, in an article entitled 'Radar Determination of the 'Scattering Properties of the Moon.' The Signal Lab research |
ers give
credit to the scientists at Jodrell Bank, England, where a 250-foot
dish-shaped antenna points skyward, for being the first to use radar to
measure ematics of his theory is complex. the fine-scale irregularities. Dr. Daniels concedes the mathemates of his theory is complex. radar signals are transmitted from the Diana site and received at a station operated by the University of Illinois at Urbana. Deductions are made from the rate at which the signals fade, and from the extent of the fading. The fluctuations, Dr. Daniels relates, are caused by the surface roughness of the moon and its constantly changing position in relation to an observer on earth. RUGGED By applying his theory to some of the data taken at Jodrell Bank and the Massachusetts Institute of Technology, in addition to the data taken by the Signal Corps, Dr. Daniels has come to the conclusion that the moon's surface is much more rugged than usually believed. The slopes of the craterlets may be so steep as to make walking difficult, although gravity is only one-sixth of that on earth, he says. Two transmitters, with wave-lengths of two meters (80 inches) and 70 centimeters (28 inches), are now being used in the moon studies. Operation on a third wavelength, of 30 centimeters (12 inches), is planned. By combining results on the three transmissions it is expected that even more refined information will be obtained. While making the terrain measurements, Dr. Daniels and Dr. Bauer also use the moon-reflected signals to obtain new information on the electron content up to a height of about 1600 miles above the earth. These findings are of great value, for example, for computing range and elevation errors for radar designed be detect at very high altitudes such objects as fast moving intercontinental missiles coming in to the earth's atmosphere. DEDUCTION Measurement of electron density also can be used to deduce temperatures at heights up to 200 miles, as Dr. Bauer reported in a recent scientific article. Following the 1946 radar contact, Signal Corps scientists considered the moon as a reflector for relaying routine messages between widely separated points on earth. This technique has been demonstrated by radio teletype-writer messages bounced to Arizona, West Germany, The Netherlands and other spots. However, the moon presents natural drawbacks as a radio mirror. Messages can be sent only between points from which it is above the horizon at the same time. Another drawback is the surface roughness, the primary cause of the Signal fading which has proved a useful tool for the terrain exploration. And in the meantime, Signal Laboratory experience with, the communications satellites Score and Courier shows they are better message relayers. Less power is need and future space vehicles are to be so deployed that communications can be maintained around the clock between all parts of the earth. In addition to its other uses, the battered old orb has served quite handily as a reflector for calibrating the equipment if satellite tracking stations spotted around the glebe. As for the terrain measurements, Dr. Daniels says, 'We shouldn't have to wait too long to confirm my theory, since it appears that within a few years satellites will be circling the moon regularly and bringing back close-up pictures. |
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Page updated August 21, 2004
page created August 21,2004
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