{"paper_id":"14e243a1-1eb3-4b99-9695-e11e1c9acdbc","body_text":"Resolving the leftover problem for habitability and biosignatures on Enceladus | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Resolving the leftover problem for habitability and biosignatures on Enceladus Antonin Affholder, Régis Ferrière, Sam Nasreldine, Francois GUYOT This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9505391/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Analysis of Cassini mission data has provided strong evidence that the subsurface ocean of Saturn's moon Enceladus may offer conditions habitable for known life. Ocean-derived material ejected in space plumes provides a unique proxy for probing the composition of this putatively habitable environment, revealing abundant resources for methanogenic microbes. However, interpreting these compositional data is complicated by the “leftover” problem: ecosystems are expected to deplete essential resources such as H 2 and phosphorus, making their observed abundance intrinsically ambiguous, and by the difficulty of setting agnostic expectations for biosignatures. Here we propose and validate a positive relationship between growth temperature and the concentration of the leftover limiting resource as a generic prediction. Our population-resource models show that putative methanogens in Enceladus’s ocean would be limited by H 2 , not by phosphorus, and that the abundant plume H 2 is inconsistent with cold-growing methanogens (<30°C) inhabiting the bulk ocean. The range of biotic hypotheses consistent with Cassini data thus narrows to methanogens inhabiting a warm seafloor environment that also supplies the plume with limited chemical alteration. More broadly, our approach shows that coupling population–resource dynamics with models of planetary interior processes provides a rigorous and general framework for interpreting surface chemical measurements as potential biosignatures. Earth and environmental sciences/Planetary science/Astrobiology Physical sciences/Astronomy and planetary science/Planetary science/Rings and moons Earth and environmental sciences/Planetary science/Geochemistry Full Text Additional Declarations There is NO Competing Interest. Supplementary Files supplementary.pdf Supplementary Information for 'Resolving the leftover problem for habitability and biosignatures on Enceladus' Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-9505391\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":637017043,\"identity\":\"0e8085b3-38e6-4539-b200-d443d446fd42\",\"order_by\":0,\"name\":\"Antonin 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Ocean-derived material ejected in space plumes provides a unique proxy for probing the composition of this putatively habitable environment, revealing abundant resources for methanogenic microbes. However, interpreting these compositional data is complicated by the “leftover” problem: ecosystems are expected to deplete essential resources such as H\\u003csub\\u003e2\\u003c/sub\\u003e and phosphorus, making their observed abundance intrinsically ambiguous, and by the difficulty of setting agnostic expectations for biosignatures. Here we propose and validate a positive relationship between growth temperature and the concentration of the leftover limiting resource as a generic prediction. 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