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Lunar Prospector Status Report #16

January 29, 1998 - 7 p.m. EST (4:00 p.m. PST)

The Lunar Prospector spacecraft continues to operate well according to Mission Control at NASAâs Ames Research Center. The current state of the vehicle (as of 0000 GMT [Zulu] on Jan. 30), according to Mission Operations Manager Marcie Smith, is as follows:

Spacecraft Orbit Number: 211
Data Downlink Rate: 3600 bps
Spin Rate: 11.94 rpm
   
Spin Axis Attitude:  
Longitude 250.7 degrees
Latitude 89.2 degrees
   
Trajectory:  
Periselene: 86 km
Aposelene: 114 km
Period: 118 minutes
   
Occultations: 43 minutes duration
Eclipses: 30 minutes duration

On Wed. Jan. 28 at 23:48 GMT, five (5) configuration commands were sent to the Magnetometer/Electron Reflectometer instrument box.

Lunar Prospector is in its second week of mapping orbit operations and has transitioned into a production mode. Now, telemetry and orbit ephemeris products are routinely generated in support of science data processing. While Lunar Prospector has no onboard tape recorders, it stores up to 53 minutes of data in solid state memory and continuously replays that delayed stream of data, along with the real-time stream. This provides access (that would otherwise be unavailable) to data collected during ground station occultations -- when the spacecraft passes behind the moon as viewed from Earth.

LP telemetry contains measurements made by each science instrument at regular intervals. Knowing the time of the measurements and having an orbit ephemeris indicating where the spacecraft was at those times, allows scientists to compile a history of measurements over each region of the moon. A very large number of measurements is required since the various data signals being measured by each instrument are low in power and high in noise level. It is only by taking a large number of such measurements that the noise on the signal can be "averaged out" (since, typically, such noise is random in nature), leaving only the true measurement behind.

Having successfully placed Lunar Prospector into the required mapping orbit and having checked out the spacecraft, scientists and engineers are now focusing the bulk of their attention on the important task of science data collection and processing (while, of course, continuing to monitor spacecraft health and other relevant vehicle and mission parameters).

David Morse
Ames Research Center
Moffett Field, CA 94035