Modelling and Characterising Spacecraft-Surface Interactions on Small Solar System Bodies

Abstract Interactions between a spacecraft and the surface of small solar-system bodies (SSB) are incredibly valuable in terms of scientific return; however, there is also a high risk associated with them. One of the main problems is the complex modelling of the interaction between the spacecraft and the surface of the SSB, which makes the touch down phase not fully predictable. This work presents novel ways of combining high fidelity simulations with data-driven methods to obtain dynamical models of the spacecraft-surface interactions. A polynomial chaos expansion (PCE) method is employed, which takes as input a small set of high-fidelity simulation runs, and generates a polynomial model from it that accurately describes the input-output relation of the original model. This PCE model can then be used to perform sensitivity and reliability analyses, which for the original model is infeasible due to numerical constraints. This model also allows to perform inverse modelling and can be used to infer the model parameters from the interaction observables. The generated model is shown to be highly accurate, capable of performing different types of statistical analyses, and allows for estimating the geophysical properties of the surface of an SSB. The novel techniques presented here will help both mission designers and scientists to perform better and more robust spacecraft operations while increasing the scientific return of this interaction.