K3PGP Experimenter's Corner
Lunar Prospector Mission 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 NASA’s 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
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