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Aviation History
1963
1963 - 0219.PDF
flJCHT International, 7 February 1963 208-209 Syncom has a passive temperature control system, i.e., adequate temperature control is achieved by the design and materials used on the external surface and by properly insulating the subsystem equipment. Control of the satellite in orbit is achieved by means of a nitrogen gas control system and a hydrogen peroxide system. The gases are contained in two pressurized spherical tanks mounted opposite each other and connected by a manifold. Each system has two jets, one firing parallel to the spin axis and the other at right angles to this axis. The nitrogen system contains 2Mb of nitrogen at 3,7501b/sq in and the other system contains 51b of 90 per cent hydrogen peroxide pressurized to 2001b/sq in by nitrogen. The nitrogen system will have a total correction capability of about 60ft/sec. The hydrogen peroxide system will have a correction capability of about 300ft/sec. Most of the electronic subsystems aboard Syncom are duplicated. The equipment includes transponders with two travelling wave tube transmitters and two receivers, of which either receiver may be used with either transmitter. One receiver has two narrow-band channels, each with a noise bandwidth of 500kc/s, and the other has a noise bandwidth of 5Mc/s. Signals are received from ground stations on two frequencies near 7,360Mc/s by one of the satellite receivers (selected by ground command). The transmitting aerial, located on the spin axis of the satellite opposite the apogee motor, comprises a slotted array of dipoles. It radiates a pancake-shaped beam with its plane perpendicular to the spin axis of the spacecraft. This 25° beam covers the Earth at all points within the line of sight. The "turnstile" aerial will be used for both command and tele metry. The telemetry data to be transmitted includes temperatures, power supply voltage and current, signal strength for communi cations receiver and transmitter, output of the solar sensors, and pressure of the nitrogen and hydrogen peroxide gas systems. The two 148Mc/s command receivers are identical; the commands to be transmitted include telemetry and communication system switching, gas jet firing, and apogee motor firing. A total of 25 command signals are available, 12 for switching the electronics equipment and 13 for satellite control. The two primary ground terminals, at Lakehurst and aboard the Kingsport, will have the Army's ground station at Fort Dix, New Jersey, as a back-up for the Syncom tests. This station lias a 60ft parabolic reflector aerial, capable of being aimed with an accuracy of 0.024". The Army's Satellite Communications Agency's Test Operations Center will have the role of linking together the three surface terminals. The Delta launch vehicle which will be used for Syncom has an excellent record of 14 consecutive successes in placing satellites in orbit. The only failure occurred on the first flight of the vehicle in May 1960, when the third stage failed to ignite. Since then, the list of spacecraft successfully launched by Delta is as follows:— 1. Echo 1, August 12, 1960 2. Tiros 2, November 23, I960 3. Explorer 10, March 25, 1961 4. Tiros 3, July 12, 1961 5. Explorer 12, August 15, 1961 6. Tiros 4, February 8, 1962 7. Orbiting Solar Observatory, March 7, 1962 8. Ariel, April 26, 1962 9. Tiros 5, June 19, 1962 10. Telstar, July 10. 1962 11. Tiros 6, September 18, 1962 12. Explorer 14, October 2, 1962 13. Explorer 15, October 27, 1962 14. Relay 1, December 13, 1962. Third "ground" communications station in the Syncom network is aboard USNS"Kingsport," anchored in Lagos harbour. The 30ft parabolic dish housed in the spherical radome is gyro-stabilized on three axes; other modifications to the shif> include the provision of a helicopter landing platform aft, and the command aerial mounted on the foremast of the ship. Main contractors included Bendix Systems and Radio Divisions and General Electric Ordnance Division ••:••• . ' • ;. :
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