Lunar Prospector Status Report #56

November 6, 1998 - 1:00 p.m. EST (10:00 a.m. PST)

Lunar Prospector Mission Status Report #55 The Lunar Prospector spacecraft continues to perform very well.

Beginning Nov 2 (DOY 306), the DSN began collecting occultation timing data for the radio science team. This campaign will continue through Nov 14.

The transmitter continues to be cycled during occultations when the propellant tank heater is on. On DOY 306, a station configuration problem caused the transmitter on commands to be delayed, causing a 24 minute data loss. A similar problem occurred on DOY 308 (4 min loss) and DOY 309 (8 min loss). These problems have occurred due to configuration changes at the station due to the radio science campaign.

Current spacecraft state (0000 GMT 11/06/98):

Orbit: 3634
Downlink: 3600 bps
Spin Rate: 12.00 rpm

Spin Axis Attitude (ecliptic):
Latitude:-89.0 deg
Longitude: 166 deg

Trajectory:
Periapsis Alt: 90.0 km
Apoapsis Alt: 110.0 km
Period: 118 min

Occultations: 37 minutes
Eclipses: 44 minutes
Propellant Remaining: 24.1 kg

The project is finalizing the timelines to turn the spacecraft 80 degrees in preparation for the Leonids Shower event. On Nov 17, the Earth passes through the orbit of the comet Tempel-Tuttle. Although the comet itself is further ahead in its orbit, it is close enough to the Earth that there will be a lot of dust. The dust will cause spectacular meteor showers as seen from the surface of the Earth, as well as cause potential damage to spacecraft in the Earth-Moon system. This year, as the comet recently came through this area, the storm is expected to be the worst it has been in 33 years. As the relative speed of the dust particles can be as high as 72 km/sec, even the very small dust particles can cause damage to the spacecraft.

Lunar Prospector will be turned so that the dust approaches the bottom of the spacecraft. This attitude was chosen because of the desire to minimize impacts on the solar panels and the fact that the propellant system at the bottom of the spacecraft is much less sensitive to this kind of potential damage than the top of the spacecraft, with its antenna and electronics. The spacecraft will be turned Nov 15 and maintained at that attitude until Nov 19.