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Aviation History
1961
1961 - 0578.PDF
588 Missiles and Space flight. . . Director of the Radio Research Station, Slough, MrJ. A. Ratcliffe, is flanked by Dr A. P. Willmore (left) and Dr R. L F. Boyd of University College, London "Flight" photograph In a paper Tracking of Artificial Satellites in the USSR, ProfMasevich stated that a network of 74 visual tracking stations attached to physics and mathematical departments of universitiesand teacher-training colleges in the Soviet Union is regularly observing Soviet and American satellites. From October 4, 1957,to April 1, 1961, more than 55,000 observations of Russian satellites and about 14,000 observations of American satellites had beenobtained. During the same period about 40,000 observations from 33 foreign countries had been sent to the Soviet computing centre. Visual observations at the Russian stations are carried out bymeans of Moonwatch telescopes (Type AT-1, 6 x 50, field of sight 11°) using equatorial co-ordinates, and by means of similarbinoculars (Type TSK) for horizontal co-ordinates. Although the average accuracy did not exceed 0.2 to 0.3sec in time, stations withtrained observers regularly obtained data correct to 0.1 sec. At the Pulkovo Observatory and other stations a combined visual-photographic method was used which enabled positions to be determined to an accuracy up to 2min of arc. Orbit predictions for Soviet satellites are sent by telegraph 2-3 FLIGHT, 4 May b ,i observatories in Alma Ata, Kazan, Pulkovo, Riga and elsewh rewhich give a timing accuracy up to 0.002sec. Radio tracking stations have studied the propagation of ra iowaves in the ionosphere and have measured the Doppler effect m addition to receiving regular signals from artificial satellites ; idspace probes. Other papers reporting detailed techniques for optical track igincluded Optical Tracking of Satellites Using a Rotating Cam< a, in which Prof D. A. Richards of the Physics Department of KUniversity College of Wales, Aberystwyth, described how ne intensity of the photographic image of a satellite could be impro edby rotating the camera at an angular velocity comparable to t ;at of the satellite. In Riperage des Temps et Reduction des Clicksselon les Methodes employees a V Observatoire de Meudon, Dr P. Muller of Meudon Observatory described the use of an IBM 650computer to convert "x,y" measurements from satellite photographs into equatorial co-ordinates using a number of known stars. A photo-electric method of satellite tracking, and in particularan advanced version of equipment designed to utilise this method, was described in The Development of a Photo-electric SatelliteTracker by P. J. Bowen and A. C. Newton of the Physics Depart- ment of University College, London. Radio tracking techniques and equipment were the subject of anumber of papers, including Radio Tracking of Satellite Vehicles by Dr G. M. Truszynski of NASA, Tracking Echo 1 at Bell Tele-phone Laboratories and Jet Propulsion Laboratories by W. C. Jakes of Bell Telephone and W. K. Victor of JPL, and Precision RadioTracking of Space Vehicles by E. B. Mullen and C. R. Woods of General Electric. Systems of attitude stabilization for satellites based on aligningthe satellite axis along the direction of the Earth's magnetic field, and along the direction of the gradient of the Earth's gravitationalfield, were described in Magnetic and Gravity Attitude Stabilization MAGNETIC DIPOLE Left, satellite with magnetic dipole moment and magnetic damping rods; below, motion of a magnetically oriented satellite in a polar orbit (from "Magnetic and Gravity Attitude Stabilization of Earth Satellites" by Fischell) Robert E. Fischell of Johns Hopkins University holds one of the nickel-iron de-spin rods of the Transit satellite days in advance to all participating stations. Orbit calculations arecarried out at the Institute for Theoretical Astronomy in Leningrad. The reduction of observations usually takes 10 to 20 days, using aBESM electronic computer, and results are published in the Bulletin of Soviet Tracking Stations. In addition to the visur.l tracking stations, there are 27 specialstations used for photographic observations in the Soviet Union. These are equipped with NAFA 3 S/25 cameras with a Uran-9lens (focal length 25cm, diameter 10cm, field of sight 30° x 50°) fitted with a special shutter. The shutter springs were strengthenedin order to reduce the shutter opening and closing time to 0.0002- 0.0003sec and so obtain sharp definition at the end of the satellitetrack. The accuracy with which positions are determined is 0.1 min of arc. The results are reduced by means of an interpolationmethod evaluated at the Pulkovo Observatory. During 1958-60 some 3,500 photographs were obtained.Although many astronomical observatories in the Soviet Union are equipped with telescopes suitable for photographing satellitesfainter than the third magnitude, "they cannot be used immediately as none of them is supplied with shutters opening fast enough forprecise time marking." Special devices have been developed at SATELLITE UWf of Earth Satellites by Robert E. Fischell of the Johns HopkinsUniversity Applied Physics Laboratory. Transit IB and Transit 2A were magnetically oriented, and in addition the spin of Transit2A was removed entirely by the use of highly permeable magnetic rods (see diagrams and photograph above). Magnetic orientation is based on the principle that a satellitewith a large magnetic dipole moment will tend to align itself, like a simple compass, along the local direction of the Earth'smagnetic field. When spinning in the Earth's magnetic field, permeable rods develop eddy-current and hysteresis energy losses,so removing the satellite's spin energy. A research satellite is currently being designed under the.dii ac-tion of Prof James Van Allen of the State University of Iowa, ;Ar Fischell disclosed, which would employ magnetic attitude stabilisa-tion to determine the directional properties of geomagnetic;-ly trapped radiation. The field of research by means of sounding rockets was veilcovered at the symposium, and an excellent example of an ir>lM<- pensive research-rocket programme was that given by Dr Le ieM. Jones of the High Altitude Engineering Laboratory, Dep. '••- ment of Aeronautical and Astronautical Engineering of —e
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