Scientific Context for Reviewing Planetary Protection Protocols for the Exploration of the Moon

Scientific context for reviewing planetary protection protocols for the exploration of the Moon. M. Anand1, C.A.Batty1, I.A. Crawford2, C. H. van der Bogert3, S. Onofri4, P. Reiss5, A. Stephant6, J. L’Haridon6, F. S. Paiva7, D.A. Pearce8 and S. Sinibaldi9, 1The Open University, Milton Keynes, UK ([email protected]), 2School of Natural Sciences, Birkbeck College, University of London, 3Institut für Planetologie, Universität Münster, 4University of Tuscia in Viterbo, IT, 5Technical University of Munich, DE, 6European Science Foundation, FR, 7KU Leuven, Celestijnenlaan 200F, Box 2404, Leuven 3001, Belgium, 8Department of Applied Sciences, Northumbria University at Newcastle, Newcastle-upon-Tyne, NE1 8ST, UK, 9European Space Agency (ESA) Introduction: There has been a global surge in missions to the Moon, most of which are intended to be landed missions. Several of these aim to explore the surface and sub-surface environments where water-ice might be present. Although the exploration for water-ice is mainly driven from a resource perspective, its scientific potential and that of associated deposits (organic and inorganic) in or near the permanently shadowed regions (PSRs) of the Moon can not be overstated (e.g. [1,2]). In this context, the potential organic contamination of the PSRs through landed missions in their vicinity or surface exploration activities elsewhere on the Moon must be assessed and shared with the global community to guide both lunar science and exploration. At the request of the European Space Agency (ESA), the European Science Foundation (ESF) assembled a working group to review the current planetary protection protocols for the Moon, specifically in the context of potential organic and biological contamination of the lunar PSRs by future surface exploration activities. This study may also serve as a springboard for evaluating the contamination of other areas of the Moon by future surface activities and the consequences for lunar science goals. COSPAR Planetary Protection Policy (PPP) for the Moon: The current COSPAR Planetary Protection Policy for the Moon is guided by its unique traits as a celestial body devoid of indigenous life but harbouring regions of substantial astrobiological interest, such as the PSRs [1,2]. Currently, the Moon falls into Category II, which states that orbiter and flyby missions should provide standard planetary protection documentation. There is no requirement for such missions to provide an organic inventory. Two further subdivisions are made for missions including activities on the lunar surface. Category IIa includes lander missions whose nominal profile does not access areas defined in Category IIb, requiring planetary protection documentation and an organic inventory limited to organic products that may be released into the lunar environment by the propulsion system. Category IIb includes lander missions whose nominal profile accesses PSRs and/or the lunar poles, in particular, latitudes south of 79°S and north of 86°N, requiring documentation and inventory required under IIa, along with an inventory of organics on the spacecraft with a mass exceeding 1 kg. Note: Category IIb applies to all PSRs, irrespective of latitude, and non-PSR regions within the latitude limits south of 79°S and north of 86°N [3]. However, it is not clear whether the existing COSPAR PPP is sufficient to adequately protect sites of special scientific interest on the Moon [1]. Contamination types and their sources: Three main lunar environments are identified, which are susceptible to organic contamination: exospheric, surface and subsurface. Exosphere and surface contamination can arise from exhaust products, outgassing materials, life-support systems, human waste, etc. However, the extent and duration over which these contaminations remain at the surface or in the exosphere are currently unknown. The level of anthropogenically introduced contamination is likely to decrease markedly with depth unless activities such as drilling, trenching, scooping, etc. are involved. A significant unknown in this context is the downward diffusion of contamination in lunar PSRs. Future laboratory experiments and numerical simulations are recommended to develop a better understanding of the potential of contaminants to reach subsurface deposits and perform ground-truthing with real data, if available. Furthermore, based on current evidence, it is quite difficult to evaluate the biological contamination of the lunar PSRs. Assessing and quantifying lunar organic contamination inventory: In many cases, the declared materials lists and inventories are provided by the spacecraft operators from which the amount of organics carried by space missions can be estimated. However, it is not yet possible to assess the impact of such contamination on compromising the scientific potential of PSRs for addressing topics such as prebiotic chemistry. Preliminary recommendations: While acknowledging the proprietary needs of the industry, we recommend an increased dialogue between the science community and industry to identify mutually agreed pathways for lunar exploration, which minimises, if not eliminates specific contamination. Meanwhile, laboratory experiments and numerical simulations should be performed to better understand the distribution and longevity of organic contaminants introduced to the lunar environment by each mission [4]. These models should be routinely updated in light of new data. Beyond organic contamination of the lunar PSRs, other types of contamination (e.g., biological, dust, nuclear, volatile, and other inorganic waste from anthropogenic activities on the Moon) should also be considered and factored into the planning of future lunar missions. A continuing open dialogue in different fora among various stakeholders is necessary to develop a common understanding and agreement for exploring the Moon in a sustainable manner, which could then become a blueprint for exploring other targets in the Solar System. References: [1] Crawford, I.A., Prem, P., Pieters, C. and Anand, M. (2022) Managing activities at the lunar poles for science. Space Research Today (215), pp. 45-51. [2] The Scientific Context for Exploration of the Moon, US National Academies Press (2007); https://nap.nationalacademies.org/read/11954/chapte r/1. [3] COSPAR Policy on Planetary Protection, Space Research Today, 211, 12-25 (2021) [4] Paiva, F. S. & Sinibaldi, S. (2025). Can spacecraft–borne contamination compromise our understanding of lunar ice chemistry? Submitted to JGR: Planets.