Lunar Prospector Status Report #53

October 16, 1998 - 1:00 p.m. EST (10:00 a.m. PST)

The Lunar Prospector spacecraft continues to perform very well.

A Mapping Orbit Correction maneuver sequence was fired Oct 12 with excellent results. The timeline for that activity is given below. There was no other commanding this week.

285/17:41 A1/A2 thruster heaters ON
285/17:47 load maneuver parameters
285/18:12 fire A1/A2 for 45.5 sec (7.22 m/s velocity increase)
285/18:40 A1/A2 thruster heaters ON 2
85/18:42 load maneuver parameters
285/19:11 fire A1/A2 for 40.9 sec (6.50 m/s velocity decrease)
285/19:17 T1 thruster heater ON
285/19:30 load maneuver parameters
285/19:34 fire T1 for 0.55 sec (despin 12.14 rpm to 12.00 rpm)

1.2 kg of propellant were used during these maneuvers.

The transmitter continues to be cycled during occultations when the propellant tank heater is on. There were no commanding anomalies that caused any data losses during the past week. There was one instance (DOY 284) when the off commands were delayed due to MCC operator error, but no data was lost. There was one instance (DOY 287), when the transmitter could not be commanded off due to a problem at DSS 54, but it did not have an adverse effect on the battery.

Current spacecraft state (0000 GMT 10/16/98):

Orbit: 3377
Downlink: 3600 bps
Spin Rate: 12.00 rpm

Spin Axis Attitude (ecliptic):
Latitude:-89.1 deg
Longitude: 156 deg

Trajectory:
Periapsis Alt: 90.6 km
Apoapsis Alt: 109.4 km

Period: 118 min
Occultations: 43 minutes
Eclipses: 46 minutes
Propellant Remaining: 24.1 kg

This orbit correction maneuver was the last one of the nominal mission. The next orbit maneuver will be December 19, when the orbit will be lowered to an average altitude of 40 km as a transition to the extended mission orbit.