Lunar Prospector Status Report #88

June 25 , 1999 - 1:00 p.m. EST (10:00 a.m. PST)

The Lunar Prospector spacecraft continues to collect good science data in the extended mission orbit. Four of five science instruments are on: the Gamma Ray Spectrometer (GRS), the Neutron Spectrometer (NS), the Magnetometer (MAG), and the Electron Reflectometer (ER). Data continues to be collected for the Doppler Gravity Experiment (DGE) as well.

Eclipses ended this week and the spacecraft will remain in sunlight for the next 3 weeks as the orbit is perpendicular to the sun/moon line.

There was no commanding this week.

Current spacecraft state (0000 GMT 6/25/99, DOY 176):

Orbit: 6589
Downlink: 3600 bps
Spin Rate: 12.12 rpm

Spin Axis Attitude (ecliptic):
Latitude: -88.7 deg
Longitude: 055 deg>

Trajectory:
Periapsis Alt: 18.0 km
Apoapsis Alt: 42.0 km
Period: 111 min

Occultations: 47 minutes
Eclipses: none
Propellant Remaining: 10.68 kg

The next orbit maintenance burn is scheduled for June 29, 1512 GMT (morning of June 29, PST). Plans are being finalized for the end-of-mission activities. On July 26, there will be a final orbit maintenance burn. On July 28, there is a lunar eclipse and special power maintenance activities are expected to reduce the battery load during that event. Over the next few days, the spacecraft will be commanded to impact the moon into a permanently shadowed crater near the south pole. Scientists will observe the impact from Earth-based telescope and from Hubble Space Telescope and hope to see evidence of water ice in the impact debris cloud. Currently the impact is scheduled for 09:52 GMT on July 31.