Verification of Planetary Protection Requirements with Symplectic Methods and Monte Carlo Line Sampling

Verification of the compliance to planetary protection requirements is an important task of interplanetary mission design, aiming to reduce the risk of biological contamination of scientifically interesting celestial bodies. This kind of analysis requires efficient and reliable numerical tools to propagate uncertainties over times up to 100 years with high precision. This paper presents a plan to improve the techniques used for planetary protection analysis in the SNAPPshot numerical tool developed at the University of Southampton for an ESA study. The Line Sampling method is presented as an alternative Monte Carlo approach to sample more efficiently the initial uncertainties, reducing the computational effort to estimate the probability of impact between uncontrolled objects and a celestial body. Symplectic integration methods are introduced as a strategy to obtain a more accurate propagation of the spacecraft trajectory starting from the initial conditions, thanks to their formulation that includes the conservation of total energy. Preliminary results are included to show the advantages and the current limitations of the proposed approaches.