Natural analogue constraints on Europa's non-ice surface material

• Published in: Geophysical Research Letters
• Main Authors: Fox-Powell, Mark G., Osinski, Gordon R., Applin, Daniel, Stromberg, Jessica M., Gázquez, Fernando, Cloutis, Ed, Allender, Elyse, Cousins, Claire R.
• Other Authors: The Leverhulme Trust, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Centre for Exoplanet Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Europa; Planetary analogues; Near-infrared reflectance spectroscopy; Brines; Arctic; Salts; GE Environmental Sciences; NDAS; GE; Canada
• Online Access: http://hdl.handle.net/10023/19063; https://doi.org/10.1029/2018GL081339

This work was funded by The Leverhulme Trust (RPG-2016-153) and the Natural Sciences and Engineering Research Council of Canada. The Planetary Spectroscopy Facility, University of Winnipeg, is supported by the University of Winnipeg, the Canada Foundation for Innovation, the Manitoba Research Innovation Fund and the Canadian Space Agency. Non‐icy material on the surface of Jupiter's moon Europa is hypothesised to have originated from its subsurface ocean, and thus provide a record of ocean composition and habitability. The nature of this material is debated, but observations suggest that it comprises hydrated sulfate and chloride salts. Analogue spectroscopic studies have previously focused on single phase salts under controlled laboratory conditions. We investigated natural salts from perennially cold (<0 °C) hypersaline springs, and characterised their reflectance properties at 100 K, 253 K and 293 K. Despite similar major ion chemistry, these springs form mineralogically diverse deposits, which when measured at 100 K closely match reflectance spectra from Europa. In the most sulfate‐rich samples, we find spectral features predicted from laboratory salts are obscured. Our data are consistent with sulfate‐dominated europan non‐icy material, and further, show that the emplacement of endogenic sulfates on Europa's surface would not preclude a chloride‐dominated ocean. Publisher PDF Peer reviewed