Abstract EANA2025-65

The identification of water ice within the Moon’s permanently shadowed regions (PSRs) has re-established the lunar surface as a compelling site for both scientific research and resource utilisation. These shadowed craters, which remain in perpetual darkness, sustain cryogenic conditions capable of preserving volatile materials introduced through cometary and meteoritic delivery, as well as through solar wind interactions. Such stable cold traps may contain not only water ice but also a range of organic molecules. These regions may act as natural laboratories for radiation-driven chemistry due to the Moon's exposure to ionising radiation, providing unique insight into prebiotic synthesis processes under minimally altered conditions (Crawford et al., 2022; Lucey, 2000; National Academies of Sciences, 2020).

Nonetheless, the astrobiological potential of PSRs is dependent on the preservation of their native chemical record, which might be compromised by contaminants introduced during lunar exploration operations, notably from spacecraft propulsion systems. As interest in the Moon intensifies, so does the need for the implementation of rigorous planetary protection strategies that ensure the scientific integrity of these regions and their potential for studying the pathways that may have led to the emergence of life.

We introduce a numerical model to simulate how volatiles released by spacecraft engines disperse and evolve within the lunar exosphere (Paiva, F. S. & Sinibaldi, S., 2025). The model was applied to a case study of ESA’s Argonaut lander descending near the lunar South Pole, focusing on the behaviour of methane (CH₄) as a representative contaminant. Simulation results indicate that approximately 50% of the emitted CH₄ becomes trapped in polar cold traps within seven lunar days, with surface interactions playing a significant role in guiding its redistribution. Notably, around 12% of the CH₄ makes it to northern PSRs, indicating the potential for cross-polar contamination and emphasising the need for informed mitigation strategies during mission planning.

References

Crawford, I., Prem, P., Pieters, C., & Anand, M. (2022). Managing activities at the lunar poles for science. Space Research Today, 215, 45-51. https://doi.org/10.1016/j.srt.2022.11.013

Lucey, P. G., et al. (2022). Volatile interactions with the lunar surface. Geochemistry, 82 (3), 125858. https://doi.org/10.1016/j.chemer.2021.125858

National Academies of Sciences (2020). Report series: Committee on planetary protection: Planetary protection for the study of lunar volatiles. Washington, DC: The National Academies Press. https://doi.org/10.17226/26029

Paiva, F. S. & Sinibaldi, S. (2025). Can spacecraft-borne contamination compromise our understanding of lunar ice chemistry? ESS Open Archive (preprint).