Lunar Prospector Status Report #84

May 28, 1999 - 1:00 p.m. EST (10:00 a.m. PST)

The Lunar Prospector spacecraft continues to collect 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.

The Alpha Particle Spectrometer was turned off May 24. The instrument has periodically seen noise throughout the mission and early this year the noise began to affect the NS instrument as well. It was turned off in February for two months to ensure collection of clean NS data at low altitude. It was turned back on April 21 and had been working well; however in the last week it began to see noise again and the noise was again affecting the NS. So the instrument has been turned off for an indefinite period of time.
The transmitter was turned off for short intervals 12 times this week during eclipse periods when the propellant tank heater was on. As eclipses are overlapped with occultations (when the spacecraft cannot see the earth), no data was lost. The battery voltage dropped to the yellow low limit for 3 heater events and to the red low limit for 3 events (out of 20 events).

All commands (68 total) executed normally this week.

Current spacecraft state (0000 GMT 5/28/99, DOY 148):

Orbit: 6226
Downlink: 3600 bps
>Spin Rate: 12.04 rpm

Spin Axis Attitude (ecliptic):
>Latitude: -88.5 deg
Longitude: 045 deg

Trajectory:
Periapsis Alt: 17.9 km
Apoapsis Alt: 42.1 km
Period: 111 min

Occultations: 48 minutes
Eclipses: 44 minutes
Propellant Remaining: 11.81 kg
The next orbit maintenance burn is scheduled for June 2, GMT (afternoon of June 1, PST).