Mars Gravity Field Determination Based on Satellite-to-Satellite Tracking Technique

Abstract

The Martian gravity field serves as the primary constraint for modeling the interior structure and changes in the surface mass. Currently, the determination of the Martian gravity field relies on ground-based tracking measurements, such as range and Doppler, conducted between Earth stations and Mars orbiters. However, these tracking methods encounter limitations in terms of observation accuracy and signal attenuation. Given the successful application of the satellite-to-satellite tracking technique in determining Earth's gravity field, as well as improving the resolution of the lunar gravity field, this paper explores its potential application to the determination of the Martian static gravity field. The objective of this research is to employ numerical simulation to assess the improvement in the precision of the Martian static gravity field achievable with the low–low satellite-to-satellite tracking (ll-SST) technique, considering various conditions, including observation durations, measurement noises, and orbital altitudes. The findings show that the intersatellite ranging system considerably enhances the global resolution of the gravity field, using the ll-SST technique at an orbital altitude of 300 km and a SST measurement noise of 1 μm s−1, the global resolution can reach at least degree 120. Reducing the measurement noise by an order of magnitude can increase the global resolution of the gravity field by 20 degrees for 300 km altitudes, and 16 degrees for 400 km altitudes. Reducing the orbital altitude by 100 km (from 400 to 300 km) results in a 20 degrees improvement in the global resolution of the gravity field.