High resolution lunar gravity anomaly map from the lunar prospector line-of-sight acceleration data

Study of the lunar gravity anomaly has not been straightforward since direct tracking data of lunar satellites are available only at its nearside. In such a case, direct inversion of the line-of-sight acceleration data into surface mass distribution has several merits, e.g., (1) high resolution can be attained without relying on artificial constraints, (2) short computation time by estimating regional parameter sets stepwise. After confirming the validity of the method using synthesized data, we processed the line-of-sight acceleration data of the Lunar Prospector extended low-altitude mission. The obtained gravity anomaly map of the lunar nearside has resolution as high as 0.8° × 0.8°, equivalent to 225th degree/order of spherical harmonics, with less spurious signatures than past studies. To take advantage of the high resolution, we calculate mass deficits for 92 medium-sized craters (50–300 km in diameter), and confirmed that they are nearly proportional to 2.5 power of crater diameter.