Evaluation of drilling-based water extraction methods for Martian ISRU from mid-latitude ice resources T.Gordon Wasilewski Space Research Centre PAS, Warsaw, Poland ARTICLE INFO Keywords: ISRU Water Mars Extraterrestrial drilling ABSTRACT Mid-latitude shallow ice deposits are an abundant feature in Utopia Planitia confirmed by SHARAD georadar. Thick ice-rich subsurface makes establishing a temporal or permanent human presence on Mars more likely because water is within reach of existing sampling technologies and conceptual production mechanisms. Although such technologies have been studied, a comparison method is needed to quantify their projected results. Herein the paper presents geological and thermal model of icy regolith created to measure water sampling and production efficiency. Various regolith and volatile sampling systems are standardized and compared using ef- ficiency factor ε. For production purposes, heat transfer is studied for down-hole and beamed energy sources, seeking for an effective heating radius for ice sublimation. Paper concludes with the chosen system for Martian subsurface water acquisition. 1. Introduction Martian water inventory, both past and present is a problem discussed broadly and thoroughly since the beginning of exploration of Mars [for instance (Lammer et al., 2003), (Lasue et al., 2013), (Carr and Head, 2015)] and outlined an interdisciplinary field of studies in geology, climatology and mineralogy with subject to extreme technological challenges. It is certain that the current Martian environment is different from ancient conditions, which allowed for (at least temporarily) liquid water to exist abundantly on the surface of the planet with most evidence shown by existence of extensive valley networks (Luo et al., 2017), outflow channels (Carr and Head, 2010), possible seas and oceans (Boyce et al., 2005), (Barker and Bhattacharya, 2017) and conditions for liquid water flow in general (Adeli, 2016). The main problem for water on Mars concerns environmental con- ditions and their decay toward the current state implying that the planet during its early history might have been ‘warm and wet’ or ‘cold and icy with temporary wet periods’ (Wordsworth, 2016), where current research tries to answer those questions in detail with climate and water cycle studies [ (Wordsworth et al., 2015), (Turbet et al., 2017), (Weiss and Head, 2017)]. Today however, with cold and icy conditions below the water triple point, Martian water resources are a domain of solid and gas phases as well as their interactions, which result in: (1) water vapour in the at- mosphere and pore space, (2) surface ice deposits (including polar de- posits and surface snow and ice), (3) shallow sequestrated ice, (4) ice- filled cryosphere (permafrost; including LDM, LDA, LVF and CCF for- mations), (5) potential groundwater below cryosphere and (6) hydrated minerals. Under current conditions, water resources are strongly connected with so-called regolith breathing, i.e. diffusive interactions between regolith ice and Martian atmosphere (Hudson, 2008). This infers that Martian water ice may be (and at large is) stable in high latitudes above 55⁰ (Schroghoffer and Forget, 2012) and at mid-latitude poleward facing slopes (Mellon and Phillips, 2001). These conditions are dynamic and strongly obliquity-driven and may change significantly over time (Head et al., 2009). Such distribution of stable ice however means that re- sources are less accessible for research and acquisition during early and critical phases of human exploration of Mars, as high-latitude and polar missions invoke higher mission risks that low-latitude ones. Recently more attention is being focused on low and mid-latitude water locations, as new and updated research finds more evidence for that state [(Stuurman et al., 2016), (Wilson et al., 2017), (Dundas et al., 2018)]. Water ice presence in such conditions inherently implies its disequilibrium state with the atmosphere, however if shallow it makes a case for establishment of temporal or permanent human presence in such Abbreviations: LDM, latitude dependent mantle; LDA, lobate debris aprons; LVF, lineated valley fill; CCF, concentric crater fill; WEH, water-equivalent hydrogen; WIP, water in place; EUR, Estimated ultimate recovery; RF, recovery factor. E-mail address: gwasilewski@cbk.waw.pl. Contents lists available at ScienceDirect Planetary and Space Science journal homepage: www.elsevier.com/locate/pss https://doi.org/10.1016/j.pss.2018.05.012 Received 15 January 2018; Received in revised form 3 April 2018; Accepted 14 May 2018 Available online xxxx 0032-0633/© 2018 Elsevier Ltd. All rights reserved. Planetary and Space Science xxx (2018) 1–9 Please cite this article in press as: Wasilewski, T.G., Evaluation of drilling-based water extraction methods for Martian ISRU from mid-latitude ice resources, Planetary and Space Science (2018), https://doi.org/10.1016/j.pss.2018.05.012