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Abstract EANA2025-36


Developing a probabilistic approach to planetary protection: back to basics

Olsson-Francis, K(1), Sephton, M(2), Carter, J(3), Fernandes, W(1), Rojek, W(1), Del Moral, A(1), Kucukkilic-Stephens, E(1), Stephens, B(1), Leite, M(1), Macey, M(1).
1AstrobiologyOU, The Open University, Milton Keynes, MK7 6AA 2Imperial College London, London, SW7 2A 3Coventry University, Coventry, CV1 5FB


Initial guidelines for planetary protection were directed by a probabilistic approach (1 ´ 10-4). Post-Viking, bioburden limits/ spore counts were introduced to the policy for target bodies like Mars, as it was concluded that Mars was less hospitable than initially believed. Yet, the probabilistic approach is still applied to Category III and IV (e.g., Europa Clipper) and Category V (e.g. Mars sample return) missions. This approach uses mathematical models to calculate the probability of the initial microbial contamination from a spacecraft contaminating a target body. It could benefit more complex missions where there is a need for a more advanced approach to planetary protection. For this to be reliable, additional scientific knowledge is required, e.g., our understanding of cleanroom contaminants, the biocidal impact of the mission environment, and the constraints of the mathematical models. As part of a United Kingdom Space Agency (UKSA)-funded interdisciplinary project, we are applying a relatively in-depth technical, mathematical and statistical approach to the planetary protection process. In this presentation, we will examine the first step in the process: estimating bioburden at launch. This includes a two-pronged approach: characterisation and quantification of microbial contamination in a clean room environment using molecular techniques and understanding the distribution of microorganisms on different flight hardware materials. This work has implications for developing a risk-informed decision approach to assess the survivability of problematic microorganisms for planetary protection.