Lunar Prospector Status Report #49

September 18, 1998 - 1:00 p.m. EST (10:00 a.m. PST)

The Lunar Prospector spacecraft continues to perform very well.

This week, as the eclipses approach maximum, the propellant tank pressure transducer was turned off and we began cycling the transmitter off during occultations when the propellant tank heater is on. The tank heater is the largest load on the spacecraft, and it comes on for about 3 hours about once each day. With this load on, the battery cannot completely recharge between eclipses. To reduce the total discharge, the transmitter is powered off for 50 minutes surrounding occultations (when the spacecraft is behind the moon as seen from earth and so we get no downlink from the spacecraft then, anyway) during heater events. The cycling data storage covers these outages and so no data is lost.

Commanding activity:

254/0426 Pressure Transducer Off

259/1713 Transmitter Off

259/1753 Transmitter On

259/1910 Transmitter Off

259/2000 Transmitter On

260/1642 Transmitter Off

260/1732 Transmitter On

261/1415 Transmitter Off

261/1512 Transmitter On (command delayed due to station problems)

261/1604 Transmitter Off

261/1702 Transmitter On

Current spacecraft state (0000 GMT 9/18/98):

Orbit: 3045
Downlink: 3600 bps
Spin Rate: 12.00 rpm

Spin Axis Attitude (ecliptic):
Latitude: 88.3 deg
Longitude: 189 deg

Trajectory:
Periapsis Alt: 89.6 km
Apoapsis Alt: 107.4 km

Period: 118 min
Occultations: 40 minutes
Eclipses: 46 minutes
Propellant Remaining: 27.8 kg