| definition
| - Spacecraft Brief Description
This RAE-B mission was the second of a pair of Radio Astronomy
Explorer satellites. It was placed into lunar orbit on June 15, 1973,
to provide radio astronomical measurements of the planets, the sun,
and the galaxy over the frequency range of 25 kHz to 13.1 MHz. The
experiment complement consisted of two Ryle-Vonberg radiometers (nine
channels each), three swept-frequency burst receivers (32 channels
each), and an impedance probe for calibration. The experiment
antennas consisted of a 229-m upper V-antenna pointed away from the
moon; a 183-m lower V-antenna pointed toward the moon; and a 37-m
dipole antenna parallel to the lunar surface. The lower V-antenna was
extended to its full 229-m length in November 1974. The spacecraft
body was a truncated cylinder 36.25 in. in diameter and approximately
31-in. high, with four fixed solar paddles. The maneuvering system
consisted of a hydrazine velocity correction package, a cold gas
attitude control system, and a solid fuel lunar insertion motor. Data
were returned to the earth via either a low power UHF/(400 MHz)
transmitter, in real time, or stored in an onboard tape recorder and
transmitted to earth via a high power UHF transmitter (400 MHz). Two
tape recorders provided backup storage. A VHF transmitter served
primarily for range and range-rate measurements and as a backup.
Commands were received on a VHF (148 MHz) receiver, which also was a
part of the range and range-rate system. Spacecraft attitude was
determined by (1) a solar aspect system, (2) a horizon sensor system,
and (3) a panoramic attitude sensor system, and was accurate to 1 deg.
The spacecraft was gravity gradient oriented (Z axis parallel to local
vertical) and was equipped with libration dampers to damp out
oscillations. For additional information, see J. K. Alexander et al.,
Astron. & Astrophys., v. 40, p. 365, 1975.
Auxiliary Information
Launch Date and Time : 1973-06-10 14:13:00
Epoch Date and Time : 1973-06-21 00:00:00
Orbit Type : Geocentric
Apogee(km) : 1063.84
Perigee(km) : 1052.98
Inclination : 55.7
Date of last update : 1992-03-09
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