P077-0006
Searching for life at Enceladus with the Orbilander mission concept

Wednesday, 16 December 2020
Poster
Shannon MacKenzie1, Marc Neveu2,3, Jonathan I Lunine4, Alfonso Davila5, Morgan L Cable6, Kathleen L Craft7, Jennifer L Eigenbrode8, Christopher R Glein9, Jason Daniel Hofgartner10, Charity M Phillips-Lander9, Jack H Waite Jr11, Dana Burton12, Robert E Gold13 and Christopher McKay14, (1)Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (2)University of Maryland, College Park / NASA Goddard Space Flight Center, College Park, MD, United States, (3)Universities Space Research Association Columbia, Columbia, MD, United States, (4)Cornell University, Department of Astronomy, Ithaca, NY, United States, (5)SETI/NASA Ames, Mountain View, CA, United States, (6)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (7)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (8)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (9)Southwest Research Institute, San Antonio, TX, United States, (10)Cornell University, Ithaca, NY, United States, (11)Southwest Research Institute, Space Sciences and Engineering, San Antonio, TX, United States, (12)George Washington University, Washington, DC, United States, (13)Johns Hopkins Univ, Laurel, MD, United States, (14)NASA Ames Research Center, Moffett Field, CA, United States
Abstract:
The search for life in Enceladus’ ocean is possible starting in the next decade thanks to the natural opportunity offered by its plumes and the progress in strategies and technology for biosignature detection and sampling. As part of the 2023-2032 Planetary Science and Astrobiology Decadal Survey, we identified a suite of science objectives to both search for life and to provide context critical to any such search by quantifying Enceladus’ geochemistry and understanding its geophysical processes. The life detection strategy is built on five complementary measurements: pathway complexity in the bulk organic fraction of plume materials, relative amino acid abundances and enantiomeric excesses, lipid abundance patterns, search for a polyelectrolyte to serve as genetic material, and search for cell-like morphologies collocated with fluorescence. The first three are organic biosignatures; these are well motivated by Cassini data and can be accomplished with flight-proven technology. The second offer the greatest orthogonality and highest reward but at some risk. While a positive life detection result would prove that Enceladus is habitable, uncertainty in how much biomass Enceladus could support can also be reduced by geochemical and geophysical measurements, providing critical information whether or not life is found. Quantifying the habitability of Enceladus’ ocean requires a better understanding of the geochemical conditions such as redox potential and disequilibria, salinity, pH, and temperature of the ocean. Furthermore, constraints on the conditions and behavior of the interior and ice shell are obtained from geophysical measurements (radar sounding, topography, imaging) and the surface (seismology). These measurements also constrain changes that ocean material may undergo upon ejection into the plume, helping understand ocean properties and processes from plume sampling. Together, these science objectives represent a robust search for life that can be executed in orbit around Enceladus and from the surface with, for example, the Enceladus Orbilander.
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