Lunar Prospector Status Report #73

March 12, 1999 - 1:00 p.m. EST (10:00 a.m. PST)

The Lunar Prospector spacecraft is operating well and collecting good science data in the extended mission orbit. Four of five science instruments are on: the Gamma Ray Spectrometer (GRS), the Neutron Spectrometer (NS), the Magnetometer (MAG) and the Electron Reflectometer (ER). Data continues to be collected for the Doppler Gravity Experiment (DGE) as well.

Cycling of the spacecraft transmitter was discontinued on DOY 065 (March 6). The transmitter had been cycled during propellant tank heater events but the heater events have become shorter due to fuel burn (used in lowering and maintaining the orbit) and there are no longer two complete night passes during a single heater on event. Review of recent data indicated that the transmitter cycling should not be required and so it has been tentatively discontinued. A procedure has been established to closely monitor the power system during heater events.

Also on DOY 065, the Propellant Tank Pressure Transducer and the Earth Moon Limb Sensor were turned off. These systems were turned off to reduce the load on the spacecraft, and will be turned on periodically as needed for maneuvers and attitude determinations.

Current spacecraft state (0000 GMT 03/12/99):

Orbit: 5229
Downlink: 3600 bps
Spin Rate: 12.00 rpm

Spin Axis Attitude (ecliptic):
Latitude: -89.5 deg
Longitude: 330 deg

Trajectory:
Periapsis Alt: 23.5 km
Apoapsis Alt: 36.5 km
Period: 111 min

Occultations: none
Eclipses: 48 minutes
Propellant Remaining: 14.78 kg