The Gravity and Rotation Models of Vesta from the Dawn Mission

The Dawn spacecraft has observed Vesta from July 2011 to August 2012. During this period, the spacecraft was tracked using ground-based DSN antennas and Vesta's surface was surveyed using the onboard optical cameras. By processing the radiometric tracking and optical imaging data, a 20x20 gravity field and a highly accurate rotation model are computed. The measured gravity field is then compared with a three-layer model of Vesta and the corresponding Bouguer gravity anomaly is presented. The inertial spin pole direction is determined to better than 0.0001 degrees and the rotation rate accuracy has been improved by a factor of 100. Moreover, alternate basis functions for gravity, such as ellipsoidal harmonics and mascons, are also presented.