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Aviation History
1962
1962 - 0612.PDF
612 FLIGHT International, 19 April 1962 US/UK SATELLITE 45° are mounted on the top spherical section. Three flush-mounted solar radiation (Lyman-alpha) gauges are mounted on the satellite skin. Two proportional x-ray counters are located opposite the Lyman-alpha gauges. Structure Basic structural material in the satellite is plastic- bonded glass-fibre. The central body section is an epoxy-bonded monofilament-wound cylinder structure;the upper dome is bonded to an aluminium ring which mates with an aluminium ring bonded to the mid-skin; and the lower dome is assembled in sections. Internally at the top of the upper dome is an aluminium disc on which is centred an integrally machined aluminium cylinder 4in deep with a 7in inside diameter. Bonded to this are eight glass-fibre stiffening ribs. At the top of the lower dome and at the bottom of the mid-skin is the instrument shelf, 0.08in thick and machined from 6061-T6 aluminium. On the underside of this shelf are eight integral stiffen ing ribs. A base ring enclosing the tape recorder and providing a structure for bolting the spacecraft to the separation flange is mounted below the shelf. Bolted to the base ring and to the instru ment shelf are six aluminium struts, two of which support boom- mounted experiments and four the solar paddles. The flush-mounted x-ray sensors are bolted to the skin. Alu minium doublers mounted inside the skin at these points give additional stiffness. Lyman-alpha gauges in the two domes are bolted to the skin and to brackets bolted to the central cylinder and the lower portion of the top shelf. The Lyman-alpha sensor located on the cylindrical section is supported only bythe skin,as is the aspect sensor. The top structure including the Cerenkov sensor, is bolted to a plate on top of the central cylinder. In the base of the spacecraft just below the tape recorder is an escapement device by which cabling is attached to the sensor booms to control their erection rate and timing. The "stretch yo-yo" de- spin system consists of two steel springs wound one half-turn eacli around the bottom of the cylinder just above the instrument shelf At the end of each spring is a relatively heavy weight. Approximate weight of the structure (without instrumentation, batteries, etc.) is 351b. Weight of the four antennas is 0.81b. Thermal design A variation of 35"C is expected within the satellite structure over a period of one year because of variations in the amount of time spent in sunlight, and shadow effects. Skin tem perature may vary from about 20C to 60°C depending on Sun spin-axis angle. The variation in temperature of boom-mounted components due to Sun spin-axis angle changes may be somewhat greater than that for the main structure, because of non-spherical geometry and greater shading effects. Solar paddle temperatures should remain between + 33°C and — 63°C. ION MASS SPECTROMETER PROBE (lid.) INERTIA BOOM In orbit, the satellite spins about the "vertical" axis through the mass spectrometer probe, stabilized by the inertia booms
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