Mission type | Radio astronomy |
---|---|
Operator | NASA[1] |
COSPAR ID | 1973-039A |
SATCAT no. | 6686 |
Mission duration | 2 years |
Spacecraft properties | |
Launch mass | 328 kilograms (723 lb) |
Start of mission | |
Launch date | 10 June 1973, 14:13:00 | UTC
Rocket | Delta 1913[2] |
Launch site | Cape Canaveral LC-17B[2] |
End of mission | |
Last contact | August 1977 |
Orbital parameters | |
Reference system | Selenocentric |
Periselene altitude | 1,123 kilometers (698 mi) |
Aposelene altitude | 1,334 kilometers (829 mi) |
Inclination | 61.3 degrees |
Epoch | 15 June 1973 |
Lunar orbiter | |
Orbital insertion | 15 June 1973, 07:21 UTC |
Explorer 49 (also called Radio Astronomy Explorer-B(RAE-B)) was a 328 kilogram satellite launched on June 10, 1973 for long wave radio astronomy research. It had four 230-meter long X-shaped antenna elements, which made it one of the largest spacecraft ever built.[2]
Explorer 49 was launched after the termination of the Apollo program, and although it did not examine the Moon directly, it became the last American lunar mission until the launch of Clementine spacecraft in 1994.
This mission was the second of a pair of Radio Astronomy Explorer (RAE) satellites, Explorer 38 or RAE-A being the first. Explorer 49 was placed into lunar orbit to provide radio astronomical measurements of the planets, the Sun, and the galaxy over the frequency range of 25 kHz to 13.1 MHz. Since the spacecraft's design used gravity gradient booms, the lumpy lunar gravity field was a problem for the mission scientists.
Explorer 49 was placed in lunar orbit to record radio measurements from 25 kHz to 13.1 MHz of the Milky Way galaxy. Explorer 49 was placed in to lunar orbit so that radio waves from earth would not be as big of an interference as Explorer 38 had discovered.[1]
The principal investigator for all the experiments was Dr. Robert G. Stone.
Data were returned to the earth via either a low power UHF/(400 MHz) transmitter, in real time, or stored in an on board tape recorder and transmitted to earth via a high power UHF transmitter (400 MHz). Two tape recorders provided backup storage.[5]
Data collected on explorer 49 was recorded on one of the three 16-mm Micro film (tape recorder) and then was returned to earth through a high power UHF/(400 MHz) transmitter. Also data could be transmitted directly to earth through a low power UHF/(400 MHz) transmitter.[6]
The third burst receiver on the dipole antenna failed after the first week and no data resulted from the receiver.[7]
Mechanical flaw in the lower V-antenna which caused the leg to only deploy to a length of 183m instead of 229m, it was corrected in November 1974 and extended to the full length of 229m.[8]
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