Recent gravity models as a result of the lunar prospector mission

The lunar gravity field is determined from the tracking data of previous mi ssions to the Moon with the 1998-1999 Lunar Prospector (LP) mission being t he major contributor. LP provided the first measurement of the gravity fiel d in a low polar circular orbit giving complete coverage at high resolution for the entire lunar nearside. However, since there is no direct measureme nt of the lunar farside from LP or any other mission, gravity details for t he farside gravity are greatly limited. Even so, it has become apparent tha t there are mascons on the farside of the Moon together with the newly iden tified mascons in the LP data for the lunar nearside. The extended mission low-altitude data (at times less than 10 km above the surface) has gravity information for the nearside to nearly degree and order 180, The 100th-degr ee lunar gravity models (LP100J and LP100K) extract most of the information from the nominal 100-km altitude. A 165th degree model LP165P attempts to model the extended mission data with some but limited success. This model p rovides a smooth solution without aliasing when evaluated up to degree 110 allowing for resolution of numerous craters. In addition, a preliminary sol ution for the lunar Love number is k(2) = 0.026 +/- 0.003. (C) 2001 Academi c Press.