Natural Analogue Constraints on Europa's Non‐ice Surface Material

Abstract

Non‐icy material on the surface of Jupiter's moon Europa is hypothesized 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 characterized their reflectance properties at 100, 253, 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 that 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.

The identification of sulfide oxidation as a potential metabolism driving primary production on late Noachian Mars

“…The waters are anoxic upon exiting the diapirs and become rapidly oxidised at the surface 2,42 . The springs that have been previously characterised with regards to their chemistry and mineralogy are Lost Hammer (LH), Gypsum Hill (GH) and Colour Peak (CP) 2,38,42,43 . These studies have indicated that the mineralogy of deposits at these spring sites are predominantly calcite (CaCO 3 ), halite (NaCl), thenardite (Na 2 SO 4 ), mirabilite (Na 2 SO 4 •10H 2 O), gypsum (CaSO 4 •2H 2 O) and elemental sulfur (S°) 38,42,43 , but variations exist between springs as a result of differences in their fluid geochemistry.…”

“…The springs that have been previously characterised with regards to their chemistry and mineralogy are Lost Hammer (LH), Gypsum Hill (GH) and Colour Peak (CP) 2,38,42,43 . These studies have indicated that the mineralogy of deposits at these spring sites are predominantly calcite (CaCO 3 ), halite (NaCl), thenardite (Na 2 SO 4 ), mirabilite (Na 2 SO 4 •10H 2 O), gypsum (CaSO 4 •2H 2 O) and elemental sulfur (S°) 38,42,43 , but variations exist between springs as a result of differences in their fluid geochemistry. For example, LH fluids have higher concentrations of sodium than CP fluids, but lower concentrations of sulfide (0.14 mM) and calcium (24.43 mM) than CP (1.8 mM and 33.23 mM respectively) 43 .…”

“…These studies have indicated that the mineralogy of deposits at these spring sites are predominantly calcite (CaCO 3 ), halite (NaCl), thenardite (Na 2 SO 4 ), mirabilite (Na 2 SO 4 •10H 2 O), gypsum (CaSO 4 •2H 2 O) and elemental sulfur (S°) 38,42,43 , but variations exist between springs as a result of differences in their fluid geochemistry. For example, LH fluids have higher concentrations of sodium than CP fluids, but lower concentrations of sulfide (0.14 mM) and calcium (24.43 mM) than CP (1.8 mM and 33.23 mM respectively) 43 . The sediments of the Axel Heiberg springs are typically highly reducing, with some sediments containing both anoxic and microaerophilic zones 38 .…”

“…The CP spring system consists of a series of springs that discharge into deep gullies located near the base of the south-facing slope of CP, as shown in Fig. 3 43 . The CP spring waters possess a broadly similar composition and pH (7.3-7.9 43 ) to that of a thermodynamically-modelled martian evaporitic fluid (based on the chemistry of Gale crater, Figs.…”

Reactivity of Cyanide at Water-Ice Interfaces: Implications for the Search for Organics on Icy Worlds

“…In any case, beyond of the very ambitious goals of the hypotheses about the origin of life, herein it is just showed that a potential wide organic chemistry can be produced from very simple carbon sources where the ice-liquid water interfases play an active role. Thus, more comprehensive and systematic synthetic studies are needed, considering other temperature ranges below 0 • C, pressures, doses of radiation, concentrations of reactants and the presence of sulfates (due to the emplacement of endogenic sulfates on Europa's surface, Fox-Powell et al, 2019), that simulate the subsurface water oceans in liquid-solid equilibrium to design the best chromatography tools and finest analytical methods for space exploration with the objective of collecting suitable data about the possible habitability of a particular icy environment. On the other hand, interpolation of the data about the plausible organics found in these icy places together with the statistical studies performed via simulation experiments could help to interpret and understand the planetary conditions under which this plausible organic chemistry has been produced.…”