Jun 10 1973
From The Space Library
June 10-20: NASA launched Explorer 49 (RAE-s; RAE 2) Radio Astronomy Explorer by a long-tank, thrust-augmented, Thor-Delta launch vehicle from Eastern Test Range at 10:14 am EDT into a transfer trajectory for the moon. The second of two approved RAE missions and the last scheduled U.S. mission to the moon, Explorer 49 was to measure galactic and solar radio noise at frequencies below ionospheric cutoffs and outside terrestrial background interference, using the moon for occultation, focusing, or aperture-blocking for increased resolution and discrimination. At 17 min after launch, the spacecraft separated from the launch vehicle's 3rd stage. One midcourse correction was made at 11:28 am EDI June 11; the planned second correction was not required. During the transfer trajectory, data acquisition from telemetry systems was excel. lent. The lunar orbit insertion motor was fired at 3:21 am EDT June 15. putting the spacecraft into lunar orbit with 1334-km (828.9-mi) apolune, 1123-km (697.8-mi) perilune, 241-min period, and 61.3° inclination, On June 18 the lunar insertion motor was jettisoned and the hydrazine-fueled velocity-control propulsion system placed Explorer 49 in a lower, near-circular orbit with a 1063-km (660.5-mi) apolune, 1052-km (653.7- mi) perilune, 22L2-min period, and 38.7° inclination. On June 20 a 37-m (120-ft) dipole antenna was extended by ground control and the, dipole experiment turned on. After a two-week calibra tion, the dipole would be retracted and the orbit adjusted as needed. The two main V antennas, joined in an X shape, would then be deployed to 183 m (600 ft). After another week, the V antennas would be deployed to their full 229-m (750-ft) length to achieve the mission's gravity-gradient, three-axis-stabilization mode. The 200-kg (442-1b) spacecraft was the first known to use boron filament for the inertial booms that helped stabilize it during the lunar trajectory. Explorer 38 (RAE 1)-the first successful radio astronomy satellite, launched July 4, 1968-had measured galactic radio sources and traced the movement of sporadic radio outbursts from the sun beyond the orbit of Mercury for four years. Explorer 38's receivers, however, had been saturated 25%-40% of the observing time by interference from the earth's radio noise. Explorer 49, in lunar orbit, would be shielded from terrestrial noise as it orbited the moon's far side. The RAE project was managed by Goddard Space Flight Center under the direction of the NASA Office of Space Science. GSFC designed, constructed, and tested the spacecraft and provided the scientific instrumentation. GSFC was also responsible for the Thor-Delta launch vehicle and the operation of the worldwide Spaceflight Tracking and Data Network (STDN) . Launch services were provided by KSC. (NASA prog off; NASA Release 73-105; GSFC SSR, 6/30/73)
June 10: Cosmos 572 was launched by the U.S.S.R. from Baykonur Cosmodrome into orbit with a 286-km (177.7-mi) apogee, 199-km (123.7- mi) perigee, 89.4-min period, and 51.8° inclination. The satellite reentered June 23. (GSFC SSR, 6/30/73; SBD, 6/13/73, 242)
A St. Louis Post Dispatch editorial commented on the repair of the Skylab 1 Workshop [see May 14-June 22] as its Skylab 2 astronaut crew surveyed the U.S. heartland from space: "Now that Skylab is operating under something approaching full power, scientists will be able to judge how well man can exist for prolonged periods of weightlessness and whether experiments they carry out cannot be duplicated or outperformed by machines. The Skylab astronauts have managed to establish conditions under which the mission may receive a fair test and that is of paramount importance, for had they failed, the manned space program, for budgetary reasons, might have come to a halt." (St. Louis P-D, 6/10/73)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
