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Aviation History
1962
1962 - 0684.PDF
682 FLIGHT International, 3 May 1%2 . OMNIDIRECTIONAL ANTENNA .RADAR AlTIMETER w- SOtAR PAN61S JHflMAt SHROUD MI0COUR5E MOTOR GAMMA-RAY SPECTROMETER • RETROROCKET ~~KK3M GAIN ANTENNA RANGER SPACECRAFT Location of the main components of Ranger 4 are indicated on this scale model. In cruise configuration the craft was 17ft in span and I Oft 3in long. Right, cutaway version of the Ford Aeronutronic instrument capsule, showing shock-absorbing balsa-wood casing and saucer-shaped telemetry antenna Missiles and Spaceflight RANGER 4 DESTROYED ON MOON IMPACT THE National Aeronautics and Space Administration's Ranger 4 spacecraft, launched by Atlas Agena vehicle from Cape Canaveral on April 23, was unable to complete its planned sequence of manoeuvres en route to the Moon because of a failure in its central computer and sequencer, and was destroyed on impact with the Moon at 12.50 p.m. GMT on April 26. As reported in last week's issue, the spacecraft was scheduled to take close-up tele vision pictures of the lunar surface and to land an instrumented capsule on the surface. The defect in the central computer was reported two hours after the launch, which was at 8.50 p.m. GMT. Following the failure of telemetry transmissions from the spacecraft, and of the craft's main electrical power supply, tracking was subsequently carried out using signals from a transmitter powered by a standby battery aboard the Ranger. A third attempt to complete the mission will be made by Ranger 5. The first attempt was that involving Ranger 3, which missed the Moon because of excessive thrust after launch on January 26. The 7301b spacecraft was scheduled to perform the following series of actions during its planned 60hr flight to the Moon: (1) Leave the Earth, achieve a parking orbit and reach escape velocity of 24,500 m.p.h. (2) Perform a three-axis manoeuvre in space to lock on to the Sun and to the Earth. (3) Accept correction commands from the Earth, change orienta tion in flight and fire a mid-course motor to place the spacecraft on a collision course with the Moon. (4) Re-establish its lock on the Sun and on the Earth. (5) Perform a terminal manoeuvre when it arrived within 5,000 miles of the Moon. (6) Take television pictures of the lunar surface as the space craft approached the Moon. (7) Make studies of the composition of the lunar surface and its radar reflection characteristics. (8) Separate a retro-rocket and capsule system from the spacecraft when it was approximately 70,000ft above the lunar surface. (9) Fire the retro-rocket to decelerate the capsule system from 6,000 m.p.h. to zero velocity some 1,100ft above the surface of the Moon (10) Detach an instrumented capsule containing a seismometer from the retro-rocket so that it would rough-land after a free fall from approximately 1,100ft, survive the landing, position itself and transmit for 30 days or more, information on "moonquakes" and meteoritic impact. Ranger 4 was 5ft in diameter at the base of the main hexagonal structure, and 8ft 3in high, in its launch configuration (solar panels folded). With solar panels extended for the "cruise" con figuration, it had a span of 17ft and was 10ft 3in high. Of the 7301b total weight, 332.11b was accounted for by the lunar capsule and retro-rocket system. The instrument capsule weighed 57.11b and its balsa-wood shock absorber 32.21b. As illustrated above, the spacecraft's lunar capsule was mounted above the retro-motor which in turn was located above the space craft hexagon. The retro-motor was to have developed a thrust of 5,0801b; its weight was 214.41b, including a small spin motor which was to rotate the assembly for stability just before the retro- motor was fired. Surrounding the sphere/retro-motor assembly was a cylindrical heat-shield designed to provide thermal control for the retro-motor. This shield was made of several layers of silvered plastic sheet. The solar panels contained a total of 8,680 cells, designed to pick up sufficient solar energy to be converted to an electric power of 175-205 watts. In one of the six boxes surrounding the base of the hexagon was a 251b silver-zinc launch and back-up battery. Three communication antennas were carried, two on the main spacecraft and one on the top of the instrumented sphere. The capsule trans mitter was powered by six silver/cadmium batteries. The two space craft antennas comprised an omni-directional antenna at the for ward end, and a 4ft diameter high-gain antenna hinge-mounted at the aft end. In the centre of the hexagon was mounted the JPL mid-course motor, a liquid monopropellant engine weighing 351b. In another of the six boxes around the hexagon was a solid-state digital computer, known as the central computer and sequencer (CCS). This system was designed to permit commands to be stored in the system for later transmission to subsystems of the spacecraft, and to permit specific ground commands to be stored in the CCS after launch for subsequent routeing to perform specific functions. The planned trajectory and mid-course manoeuvres for Ranger 4 were the same as for Ranger 3, illustrated and described in our issue of January 25,1962. [Missiles and Spaceflight section continued on page 712]
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