Data Set Overview : The Lunar Prospector ephemeris data set consists of spacecraft position and velocity determinations as a function of time in Moon-centered, Earth equator, mean of J2000 coordinates. Tracking data collected by ground stations are used by the Goddard Flight Dynamics Analysis Branch (FDAB) to compute the Lunar Prospector orbit ephemeris. The Level 0 Data archive contains the ephemeris type known as the 'definitive ephemeris', which is based on an updated lunar gravity model [FDAB1997].  Each file in the ephemeris data set covers 24 hours. On days when there was a spacecraft maneuver, the ephemeris file may contain two ephemeris solutions.  Science Objectives : The Lunar Prospector science objectives relevant to this data set are to map the Moon's surface composition and its magnetic field, and to determine the frequency and location of gas release events. A special emphasis of the science objectives is to search for polar water ice deposits [BINDERETAL1998]. The spacecraft ephemeris data are used to locate where on the Moon science data were acquired.

Confidence Level Overview : The Lunar Prospector definitive orbit ephemeris files, processed with the updated lunar gravity model, are accurate to within +/- 1 km in position and +/- 1 m/sec in velocity [FDAB1997].  Data Coverage and Quality : Ephemeris data exist for the entire Lunar Prospector Primary and Extended Missions.