Spatially Resolved Spectroscopy of Europa: The Distinct Spectrum of Large-scale Chaos

Abstract

We present a comprehensive analysis of spatially resolved moderate spectral resolution near infrared spectra obtained with the adaptive optics system at the Keck Observatory. We identify three compositionally distinct end member regions: the trailing hemisphere bullseye, the leading hemisphere upper latitudes, and a third component associated with leading hemisphere chaos units. We interpret the composition of the three end member regions to be dominated by irradiation products, water ice, and evaporite deposits or salt brines, respectively. The third component is associated with geological features and distinct from the geography of irradiation, suggesting an endogenous identity. Identifying the endogenous composition is of particular interest for revealing the subsurface composition. However, its spectrum is not consistent with linear mixtures of the salt minerals previously considered relevant to Europa. The spectrum of this component is distinguished by distorted hydration features rather than distinct spectral features, indicating hydrated minerals but making unique identification difficult. In particular, it lacks features common to hydrated sulfate minerals, challenging the traditional view of an endogenous salty component dominated by Mg-sulfates. Chloride evaporite deposits are one possible alternative.

References in corpus (3)

• The pH of Enceladus' ocean
• Salts and radiation products on the surface of Europa
• A Search for Magnesium in Europa's Atmosphere

Cited by in corpus (14)

• Ocean dynamics of outer solar system satellites
• The distribution of CO${}_2$ on Europa indicates an internal source of carbon
• H${}_2$O${}_2$ within chaos terrain on Europa's leading hemisphere
• ALMA Thermal Observations of Europa
• The origin and fate of O${}_2$ in Europa's ice: an atmospheric perspective
• ALMA Thermal Observations of a Proposed Plume Source Region on Europa
• Bayesian analysis of Juno/JIRAM's NIR observations of Europa
• Near-Infrared reflectance spectroscopy of sublimating salty ice analogues. Implications for icy moons
• Surviving in Ocean Worlds: Experimental Characterization of Fiber Optic Tethers across Europa-like Ice Faults and Unraveling the Sliding Behavior of Ice
• Europa's H${}_2$O${}_2$: Temperature Insensitivity and a Correlation with CO${}_2$
• Spectroscopic mapping of Io's surface with HST/STIS: SO${}_2$ frost, sulfur allotropes, and large-scale compositional patterns
• Evolution of granular salty ice analogs for Europa: Sublimation and Irradiation
• Endogenic and Exogenic Contributions to Visible-wavelength Spectra of Europa's Trailing Hemisphere
• Feature Extraction and Classification from Planetary Science Datasets enabled by Machine Learning