The sub., 1946-01-31


 radio waves, much as a prism dis torts light waves. By checking radar data against visual data pro- vided by astronomers, 1t will be possible to compute accurately the effects of this distortion.
 Another valuable application may be the provision of new as- tronomical information. Not only may it be possible to construct de- tailed typographical maps of dis tant planets with the aid of radar data, but scientists may be able to determine the composition and at- moSpheric characteristics of other celestial bodies by this means. A less likely application of the new technique will be the possi- bility of radio control from the earth's surface of "space ships" venturing thousands of miles from the earth, and the radio reporting of astronomical data electronically computed aboard such vessels. The equipments used by the Sig- nal Corps for this experiment com- prised extensive adaptations to a Istandard wartime Signal Corps ra- dar known as Radio Set SCRIPT, originally designed in 1897 for long-range early warning against enemy air attacks. It was an early model of this set which detected Japanese planes approaching Pearl Harbor on December 2. 1941, while they were 132 miles distant. The radar was operated at It's standard frequency of 112 mega cycles-its alternating current ra- dio waves made 112,000, 600 com- plete cycles per second-but the pulse repetition rate and pulse width were extended beyond the usual standards. Instead of send- ] ing out several thousand spaced pulses each second, the modified radar transmitted a pulse only ev- cry five seconds. The pulse width was increased from a few mill lionths of second to as much as one-half second. This equipment, therefore, sent out a half-second pulse of radio energy every i've seconds.
 A specially designed high persis- tency oscilloscope, comparable to the "A-scope'' used on wartime ra- dars, was constructed to present visual evidence of the moon echoes. When the radar was operating, a line across the face of the tube rep resented the transit of the success sive pulses. As each pulse left the transmitter, a tall ."pip" appeared at one end of this line. A smaller pip, toward the other end of the line, represented the pulse echo re- ceived from the moon.
 A double-sized antenna with GA instead of the standard 32 dipoleS was mounted on 100-foot tower within the heavily guarded confines of the Signal Laboratory for this experiment. The antenna was "aimed' at the moon optically by means of a specially constructed peep-sight.
 To prevent the set from being burned out by the enormous pulse power it had to generate, water cooled vacuum tubes were used.
 The Evans Signal Laboratory, formerly designated Camp Evans, grew from the original Signal Corps Radar Laboratory, where the first radar built in America was constructed by the Signal Corps i: 1886.
 A staff of mathematicians and physicists spent weeks computing the trend in relationship between the earth and the moon, before as- sembly of the equipment began. It was necessary to determine accu- rately the speed of the moon rela- tive to the movement of the earth. This speed varies from 750 miles faster than the earth's rotation (computed as at Belmar) to 750 miles slower.
 RWVV