Lunar Prospector Status Report #9

January 14, 1998 - 3:00 p.m. EST (12:00 noon PST)

The Lunar Prospector spacecraft continues to operate nominally. The vehicle is in perfect health, and all of the science instruments are operating and collecting data, as planned.

No command activities were scheduled for the past 24 hours as the operations team, which had been working around the clock with most major activities occurring during the night hours, began a transition to move command activities into daylight hours. Overall, operations continue, of course, on a 24-hour basis.

Spacecraft occultations (where the spacecraft passes behind the Moon as seen from the Earth's ground stations) began on a "once-an-orbit" basis, starting at 10:54 a.m. PST yesterday. The first one lasted for about 7 minutes, and they have subsequently (and already) increased in length to 33.5 minutes. As the Moon goes around the Sun, occultations will repeat with a 14-day cycle -- 11 days with occultations and 3 days without them.

Solar eclipses begin in about 8 days and, as they are related to the position of the Sun, they will repeat in half-year cycles. Consequently, missions operations personnel report that we will experience eclipses every orbit for 147 days, then 40 days without eclipses, before repeating the cycle.

The final determination on the spacecraft's current preliminary mapping orbit shows the vehicle to be in a 92 x 153 km (57.5 x 95.5 mile) orbit. The inclination is 90.1 degrees and the orbit period is 2 hours (very close to the pre-launch 118-minute predict). This will be trimmed on Thursday afternoon, Jan. 15 (PST), to put the spacecraft into a more circular orbit -- within the desired 100±20 km (62.5±12.5 mile) orbit. Some science configuration commanding is being performed during the day today, Jan. 14.

David Morse
Ames Research Center
Moffett Field, CA 94035