Ninth International Conference on Mars 2019 (LPI Contrib. No. 2089) 6279.pdf

THE CASE FOR MARS SUBSURFACE EXPLORATION. L. W. Beegle1, V. Stamenković1, K. Zacny2.1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA. 2Honeybee Robotics, New York, NY, USA.

The Martian subsurface is of enormous interest for Orbiters, landers and rovers, especially the two astrobiology, geochemistry, climatology, and In Situ MERs and Curiosity, have delivered data that have revo- Resource Utilization (ISRU) objectives, which cannot lutionized our understanding of ancient Martian surface be addressed with surface missions alone. Specifically, environments. Those data support a rich history of subsurface data are needed to continue the search for groundwater flow and a diverse, and from the surface extinct of extant life started by the Viking landers more very different, world hiding beneath the oxidized surficial than forty years ago and to prepare for human explora- regolith. InSight and future missions like the ExoMars tion. If Mars ever had life, whether it emerged on or and Mars 2020 rovers will aim to extend our knowledge of ancient habitable surface environments, to produce below the surface, then as the atmosphere thinned and unprecedented data on global large-scale interior proper- global temperatures dropped[1], life may have fol- ties, and to inform us about the very shallow Martian lowed the groundwater table to progressively greater regolithic subsurface. However, questions, in particular depths where stable liquid water could persist. At such about whether there ever was or is still life on Mars, how depths, life could have been sustained by hydrothermal the Martian climate changed over long periods of time, activity and rock-water reactions. Hence, the subsur- whether there still is liquid water and whether there are face likely represents the longest-lived habitable envi- enough accessible resources for an extended human pres- ronment on Mars. Moreover, while the preservation of ence, will remain unanswered until we start to ‘go deep- ancient molecular biosignatures on Mars is debated, the er’. ‘Going deep’ and using Mars as a testbed for subsur- consensus is that detection at depths greater than a few face exploration was recognized as a critical step when meters is favored because of the shielding from harm- searching for life by the National Academy of Sciences ful radiation [e.g., 2, 3] and the possibility to preserve Committee on the Strategy for the Search for Life in the water/ice resources. Universe [7]. On one hand, if Mars hosts extant life, then the ‘Going deep on Mars’ is an interdisciplinary project most likely place to find evidence of it may well be at that calls for expertise from the whole Mars community. depths of a few hundred meters to many kilometers, It does not only bridge astrobiology, polar sciences, cli- where groundwater may persist depending on local mate, surface geology, geochemistry, spectroscopy, geo- geothermal gradient [e.g., 4, 5]. On the other hand, we physics and ISRU, but it builds on existing technologies also face today the need to determine the presence and and scientific expertise that are part of current and future missions like Curiosity, InSight, Mars 2020, ExoMars and accessibility of resources for potential use (ISRU) and the present orbiters around Mars. Moreover, Mars subsur- hazards to human health within the Martian subsurface, face exploration deeply connects planetary sciences with as part of the process of planning future human mis- the human exploration program, linking the search for sions to the Red Planet. usable resources and hazards to the quest for signs of past The need to explore the Martian subsurface for as- and especially present life, ices and liquid water. The trobiology/science and resource purposes, with the emerging capabilities of Mars subsurface science and support of national space agencies, academia, and the exploration technology in combination with the commer- commercial sector has motivated a Keck Institute of cial space market have positioned the Martian under- Space Studies workshop titled “MarsX: Mars Subsur- ground as the next great frontier of human endeavors. As face Exploration for Life and Resources”, held Feb. such, implementing a bold program of Martian subsurface 12-16, 2018 in Pasadena, CA, with participants from exploration — with a focus on extant and extinct life, NASA, JPL, ESA, SpaceX, Schlumberger, Honeybee ISRU and past climate — would serve as an ideal central Robotics, and various universities and research insti- focus for NASA’s next Planetary Decadal Survey. tutes. It also lead to a recent community-driven publi- References: [1] Jakosky, B. M. et al., (2017), Science cation in Nature Astronomy [6] presenting the technol- 355, 1408–1410. [2] Kminek, G., and J. Bada, (2006), ogy that would enable Mars subsurface exploration in EPSL, 245(1-2), 1-5. [3] Pavlov et al., (2016), LPSC, the next decade. We specifically find that Mars subsur- Abstract 2577. [4] Clifford, S. M., et al., (2010), JGR, face missions can today capitalize on recent technological 115(E7). [5] Grimm, R.E. et al., (2017) J. Geophys. achievements for sounding, drilling, cave exploration, and Res. Planets, 122, 94–109. [6] Stamenković et al. in situ sample analysis, on progress in our scientific 3D (2019), Nature Astronomy 3, understanding of the Martian subsurface, and on com- https://www.nature.com/articles/s41550-018-0676-9. mercial and small spacecraft opportunities. Here, we will [7] National Academies of Sciences, Engineering, and present these opportunities and discuss the scientific ra- Medicine An Astrobiology Strategy for the Search for tionale for ‘going deep’ on Mars. Ninth International Conference on Mars 2019 (LPI Contrib. No. 2089) 6279.pdf

Life in the Universe (The National Academies Press, Washington, DC, 2018).

Acknowledgements: Part of this research was car- ried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the Na- tional Aeronautics and Space Administration.