Reports Homepage Reports Archive

Lunar Prospector Status Report #58 November 20, 1998 - 1:00 p.m. EST (10:00 a.m. PST) The Lunar Prospector spacecraft is operating well and saw no anomalies or status changes due to the Leonids shower this week. Science instruments continued to collect good data throughout the week. The spacecraft was turned 80 deg on 11/15 to minimize the cross sectional area of the solar arrays in the direction of the shower. A trim maneuver was executed 11/16. On 11/19, the spacecraft was turned back to the nominal attitude with the spin axis nearly aligned with the ecliptic south pole. A summary of events is given below. All maneuvers involved pulse firing jets A1&A4 for 0.2 seconds each pulse. These large maneuvers were broken up into segments because they had to be done during the 10-15 minutes twice each orbit that the spacecraft was between occultation (where the signal to earth is blocked by the moon), and eclipse (where the sun is blocked by the moon). The sun is the reference on the spacecraft for timing the pulses and so all pulsed maneuvers are only executed in sunlight. Attitudes are in ecliptic coordinates, latitude/longitude. 11/15 80 deg reor (executed in 7 segments): 319/15:00 Switch downlink to OMNI antenna 319/15:41 Fire 55 pulses; slew 11.3 deg starting attd: -88.9/166 319/16:44 Fire 55 pulses 319/17:39 Fire 55 pulses 319/18:45 Fire 55 pulses 319/19:37 Fire 55 pulses 319/20:41 Fire 55 pulses 319/21:35 Fire 49 pulses; slew 10 deg target attd: -12.1/327.4 measured attd: -20.7/327.3 Total reorientation used 1.11 kg of propellant 11/16 8 deg attitude trim 321/0006 Fire 40 pulses; slew 8.0 deg; used 0.11 kg of propellant starting attd: -20.7/327.3; target attd: -12.7/327.7 measured attd: -11.5/327.4 11/19 80 deg reor 323/17:55 Fire 110 pulses; slew 22.5 deg starting attd: -14.0/326.9 323/18:56 Fire 110 pulses 323/19:53 Fire 110 pulses 323/20:56 Fire 40 pulses; slew 3.1 deg target attd: -89.4/270.0 measured attd: -89.1/289 Total reorientation used 1.07 kg of propellant The transmitter continues to be cycled during occultations when the propellant tank heater is on, although as eclipses get shorter, it has not been cycled as regularly. There was one instance (DOY 321) where the planned transmitter cycling commands could not be transmitted due to a combination of station and MCC problems but it had no impact on the battery.       Current spacecraft state (0000 GMT 11/20/98): Orbit: 3805 Downlink: 3600 bps Spin Rate: 12.07 rpm Spin Axis Attitude (ecliptic): Latitude:-89.1 deg Longitude: 307 deg Trajectory: Periapsis Alt: 93.0 km Apoapsis Alt: 107.0 km Period: 118 min Occultations: 38 minutes Eclipses: 41 minutes Propellant Remaining: 21.8 kg A trim maneuver tentatively scheduled for this afternoon has been cancelled as the attitude is so close to the target.       brief summary of terms detailed summary of terms