Simulation of a Satellite Gravimetry Mission at Mars

Improving the data on the gravitational field of Mars can yield enhanced knowledge about Martian planetary dynamics and subsurface water reservoirs. In this study, we augment the VENQS software tool to perform simulations for a future dedicated satellite gravimetry mission at Mars following the archetype of GRACE-FO and as a result to study the challenges of such a mission. The VENQS software tool consists of two parts: the VENQS App and the VENQS library. The VENQS App provides users with an easy access to a variety of simulation models, that can be combined to an individual VENQS library setup. These simulation models include amongst others orbit propagation of single satellites with embedded test masses, simulations of satellite constellations, and detailed disturbance analysis for satellites due to the space environment. Interaction with versioning systems allows the VENQS App to effectively track the software of the simulation models. In addition, a dedicated release management system enables the provision of different versions of the VENQS library. Initially designed for satellites orbiting Earth, we are working on an augmentation of the VENQS library for interplanetary spacecraft or to be more precise for satellites orbiting arbitrary celestial bodies. In this context we want to propose the adaptation of VENQS for precise orbit propagation at Mars, which can assist the assessment of different mission influences on gravity field recovery (via dedicated software tools such as GRAVFIRE). We present the general simulation procedure including the modelling of perturbating forces along with gravitational acceleration for the orbit integration. Furthermore, we explain the differences to simulations of terrestrial spacecraft and outline occurring challenges with Martian atmosphere, time and reference frames, solid Mars tides as well as more complex satellite geometries inducing micro-vibrations and the non-availability of GNSS, that may deteriorate gravity field solutions.