An experimental estimate of Europa's “ocean” composition independent of Galileo orbital remote sensing

Abstract

Abstract. We have conducted a series of experiments designed to simulate, in the laboratory, the development of any subsurface aqueous phase on Europa. In our theoretical-experimental approach we select a single natural sample (a CM meteorite) that based on cosmochemical considerations, we consider to approximately represent the bulk material that accreted to form Europa. We then subject the sample to a hot water leaching procedure designed to simulate low-to moderate-temperature aqueous alteration. The resulting leach solution was then subjected to a series of sequential fractional crystallization steps producing a series of ices and residual brines. Then all this brines and ices are multiply analyzed for Na, Ca, Mg, Sr, Ba, Fe, Mn, K, CI, and SO4. Results were found to be remarkably consistent between brines and ices in the same stages of crystallization and also between stages. We found that any putative aqueous phase below Europa's ice crust is probably a brine with cations: Na -Mg > Ca, K> Fe and anions: SO4 >>C1. Our results are in harmony with inferences drawn from one of the two main current interpretations of the orbital spectral data but cannot definitively rule out inferences drawn from the alternative interpretation. This is so because the mineralogy of the top 200/xm may not reflect the chemical composition of bodies of brine below the solid surface owing to extensive alteration caused by magnetospheric bombardment.

Induced Magnetic Fields in Solar System Bodies

“…However, the derived electrical conductivity of 0.25 S/m cannot be achieved by frozen or soft ice, but only by liquid saline water in the context of Hand and Chyba (2007) including lower limits of the electrical conductivity from and the discussed constraints of this paragraph. Most theoretical studies (Kargel et al 2000;Zolotov and Shock 2001;McKinnon and Zolensky 2003) as well as aquateous leaching experiments (Fanale et al 2001) suggest MgSO 4 and not NaCl, as the dominant salt in Europa's ocean. In Fig.…”

Chemistry of Frozen Sodium–magnesium–sulfate–chloride Brines: Implications for Surface Expression of Europa’s Ocean Composition

“…Previous theoretical and experimental simulations (Fanale et al 2001;Zolotov & Shock 2001) strongly suggest that the composition of surface ices on Europa results from ocean materials; other studies based on observational data (Carlson et al 2009;Brown & Hand 2013;Dalton et al 2013) argue that certain surface species (e.g., MgSO 4 •7H 2 O and H 2 SO 4 •nH 2 O) are radiation products. Given the significance of sulfate as an electron acceptor for prokaryotes, Europa's potential for habitability is directly linked to whether these oxidized sulfur species have been delivered from, or could be delivered to, the ocean beneath.…”

Hydrothermal plume dynamics on Europa: Implications for chaos formation

“…However, planetary chemical evolution models [Kargel et al, 2000;Fanale et al, 2001] and a possible detection of salts on Europa's surface [McCord et al, 1998] suggest that the ocean is salty. Salt is not readily incorporated into ice as it freezes, so negatively (positively) buoyant fluid is released as ice forms (melts).…”