K3PGP Experimenter's Corner
Lunar Prospector Mission Status Report #15
January 26, 1998 - 07:00 p.m. EST (4:00 p.m. PST)
The Lunar Prospector spacecraft continues to operate well according to Mission Control at NASA's Ames Research Center. The current state of the vehicle (as of 0000 GMT [Zulu] on Jan. 27), according to Mission Operations Manager Marcie Smith, is as follows:
| Spacecraft Orbit Number: | 174 |
| Data Downlink Rate: | 3600 bps |
| Spin Rate: | 11.94 rpm |
| Spin Axis Attitude (maneuver target): |
Longitude -- 352 deg Latitude -- 89.3 deg |
| Trajectory: | Periselene: 88 km Aposelene: 112 km Period: 118 minutes |
| Occultations: | None |
| Eclipses: | 25 minutes duration |
During the day on Jan. 26, 24 commands were sent to the Lunar Prospector spacecraft to reorient the spin axis and trim the spin rate. The spin axis is now approximately aligned with the ecliptic north pole, but it is tilted about 1 degree or so towards the sun for thermal reasons and to reduce boom shadowing on the solar arrays. As the Earth moves around the sun, the spin axis must be "tweaked" a bit to maintain this configuration.
The spin rate was trimmed to keep it within the boundary constraints desired for gravity mapping. The rate will be kept to 12.00 ± 0.10 rpm during the first two months of the mission to assist in achieving the gravity mapping objectives of the mission.
A detailed timeline of today's commanding events (expressed in GMT/Zulu time) is provided below:
| 16:52 | Thruster heaters commanded on |
| 17:18 | Reorientation maneuver -- 12 pulses were fired to precess the spacecraft spin axis 2.4 degrees |
| 17:20 | Reset thrusters |
| 17:28 | Thruster heater commanded on |
| 17:54 | A spin trim was conducted to reduce the spin rate of the spacecraft from 12.098 rpm to 11.936 rpm via a 0.61 second thruster burn |
| 17:54 | Reset thrusters |
As of 4:00 p.m. PST today (Jan. 26), no further spacecraft commanding or science instrument commanding events are currently scheduled for the upcoming period.
David Morse
Ames Research Center
Moffett Field, CA 94035
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