Surface Gravity Modelling and Space Gravimeter Development in the Context of Solar System Small Bodies

The two planetary defense ESA Hera and NASA DART missions aim at demonstrating asteroid deflection capabilities. The former will follow the latter to the binary asteroid system Didymos. One payload of the Hera mission is the GRAvimeter for small Solar System bodies (GRASS) to land on Dimorphos for in-situ surface gravimetry. This will be the first-ever extraterrestrial surface gravimeter experiment on a small body. The present PhD thesis contributed to this novel instrument development, from early prototyping to the final instrument flight model (FM), scheduled for launch in 2024. The preparation of gravimeters to any celestial target, but moreso the interpretation of the finally returned data to Earth, demand excellent (surface) gravity simulations. Especially on small, generally non-spherical, bodies, this is non-trivial and ddressed further in this work. Different contributions to gravity and the different existing gravitation modelling methods are introduced. Then, a comparison of three of these methods is performed, and the surface gravity for different cases, including Hera's target, are simulated. Finally, zooming in from the global to the local scale, the novel Wedge-Pentahedra Method (WPM) is presented, allowing to account for local topography surrounding a gravimeter measurement location and influencing the measurement.