A systematic performance-oriented tuning for space exploration descent & landing

Descent & landing (D&L) on planetary bodies are scientifically rewarding exploration missions but they are technically challenging due to the complex and poorly-known environment around those bodies. The standard guidance synthesis approach considers nominal conditions and applies optimal control theory to obtain guidance law gains, followed by intensive verification and validation. In this article, it is shown that the standard approach may yield gains that are not optimal once dispersions (and/or other optimal metrics) are taken into account and a tuning approach is then proposed based on a priori methodological system assessment. The proposed approach employs systematic high-fidelity simulations to generate trade-off maps on ground that can be uploaded once the spacecraft approaches the target, with its actual conditions in mind. This also provides a valuable understanding of the system dynamics towards the application of other industry-oriented tools including structured H∞ optimisation. It is shown that this approach enables propellant consumption reductions of around 40% compared to state-of-practice tuning selections.