Europa Deep Dive 2: Composition 2018 (LPI Contrib. No. 2100) 3018.pdf

INVESTIGATING THE SURFACE COMPOSITION OF EUROPA WITH THE . R. L. Klima1, J. Soderblom2, M. Gudipati3 and the Europa Clipper Composition Working Group. 1Johns Hopkins University Applied Physics Laboratory, Laurel, MD ([email protected]); 2Massachussetts Institute of Technology, Cambridge, MA; 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA.

Introduction: The composition of the ice and vestigated via the spacecraft telecom system com- non-ice materials on Europa’s surface provides im- bined with REASON altimetry, while a planned radia- portant clues for understanding habitability. A portion tion monitoring system will provide valuable scien- of the non-ice surficial material may be sourced from tific data about the environment around Europa. below the ice shell, suggesting communication be- Composition Investigations: Though all of the tween an internal ocean and the surface, but much of Europa Clipper investigations provide critical input it may also be exogenic, accumulated on top of the for understanding the composition of Europa, MISE, icy shell [1,2]. Previous missions, including Voyager Europa-UVS, MASPEX, and SUDA are explicitly and , have provided tantalizing clues about designed to investigate the mineralogical and chemi- the composition and origin of the distinctive surface cal composition of the surface and/or exosphere, materials, but many questions remain, including: (1) providing key constraints on the origin of surface ma- What is(are) the specific composition(s) of the non- terials. Coupled with high-resolution EIS panchro- ice material(s) on Europa’s surface? (2) What role matic and color observations, data from these instru- does Europa’s radiation and plasma environment play ments may be traced back to specific surface regions, in processing this material? (3) What are the composi- and in some cases specific landforms, to understand tional and chemical pathways in the ocean? The Eu- the relative contributions of endo- and exogenic mate- ropa Clipper mission will investigate these questions rial to Europa’s surface composition. with a robust suite of instruments, providing answers Among the data sets that will be collected by Eu- that will aid in constraining the habitability of Euro- ropa Clipper are MISE global (<10 km) and regional pa’s ocean through composition and chemistry. (<500 m) scale hyperspectral image cubes. These data The Europa Clipper: The overarching science will reveal infrared absorption features due to hydrat- goal of the Europa Clipper mission is to investigate ed salts, any organics, water ice in various phases, and Europa’s habitability with the following specific sci- radiolytic products, providing the necessary data to ence objectives: (1) Ice Shell & Ocean: Characterize resolve many ambiguities in previous compositional the ice shell and any subsurface water, including their analyses [e.g., 1]. UV observations, which were re- heterogeneity, constrain ocean properties, and the ported by [2,3] as being effective in highlighting ex- nature of surface-ice-ocean exchange; (2) Composi- ogenic material on the surface, will be collected at tion: Understand the habitability of Europa’s ocean both global and regional scales by Europa-UVS. through composition and chemistry; (3) Geology: These observations will provide further constraints on Understand the formation of surface features, includ- the relative contributions of exo- and endogenic mate- ing sites of recent or current activity, and characterize rial. SUDA will determine the composition of parti- high science interest locales, including any plumes or cles ejected from the surface due to sputtering, track- thermal anomalies. NASA has selected a highly capa- ing the trajectories of these particles to their origin on ble instrument suite for this mission, including those the surface, as well as distinguishing and characteriz- that will directly sample and particles around ing incident exogenic dust. MASPEX will measure Europa and those that will globally characterize the neutral gas composition in the exosphere, including surface and near subsurface through remote sensing, potentially exchanged ocean-surface material, deter- covering wavelengths from ultraviolet through radar. mining ocean salinity in correlated measurements These instruments include: (1) Europa Ultraviolet with SUDA. We will present an overview of these and Spectrograph (Europa-UVS); (2) Europa Imaging other synergistic compositional investigations that System (EIS); (3) Mapping Imaging Spectrometer for will be performed by the Europa Clipper mission. Europa (MISE); (4) Europa Thermal Imaging System References: [1] Carlson, R.W. et al., (2009) Eu- (E-THEMIS); (5) Radar for Europa Assessment and ropa's Surface Composition, in Europa, eds. Pappa- Sounding: Ocean to Near-surface (REASON); (6) lardo, R. T., McKinnon, W. B. and Khurana, K., U of Interior Characterization of Europa using Magne- Ariz. Press, Tucson, 786p. [2] McEwen, A. S. (1986). tometry (ICEMAG); (7) Plasma Instrument for Mag- Exogenic and endogenic albedo and color patterns on netic Sounding (PIMS); (8) MAss Spectrometer for Europa. JGR Solid Earth, 8077–8097. [3] Becker, T. Planetary EXploration (MASPEX); and (9) SUrface M. et al., (2018). The Far-UV Albedo of Europa From Dust Analyzer (SUDA). Gravity science will be in- HST Observations. JGR Planets, 123.