Thermal Diapirism and the Habitability of the Icy Shellof Europa

Abstract

Europa's chaos and lenticulae features may have originated by thermal diapirs related to convective plumes. Warm ice plumes could be habitable, since their temperature is close to the ice melting temperature. Moreover, thermal plumes intruding into the lower stagnant lid warm several kilometers of country ice above 230 K for periods of 10(5) years, and hundreds of meters above 240 K for periods of 10(4) years. Diapir coalescence generating chaos areas should provide a large zone with temperature above approximately 240 K for thousands of years. A temperature above approximately 230 K is potentially interesting for astrobiology, since it corresponds to the lowest temperature at which microbial metabolic activity in Antarctic ice has been reported. So, the warming by thermal plumes could cause an aureole of biological activation/reactivation in the country ice. Adaptation of life to either high salinity or low temperature is similar: it requires the synthesis of compatible solutes, like trehalose or glycerol, which are efficient cryoprotectants. We therefore propose that the future astrobiological exploration of Europa should include the search for compatible solutes in chaos and lenticulae features.

Descent without Modification? The Thermal Chemistry of H2O2 on Europa and Other Icy Worlds

“…The possibility of life within and below the surface ices of Europa has been the subject of numerous studies following reports from NASA's Galileo mission, suggesting that liquid water may exist below the surface ice (Carr et al, 1998). Life beneath the ice shell has been treated by Gaidos et al (1999), while life within the ice itself, perhaps aided by rising sub-surface thermal plumes, has been examined by Ruiz et al (2007).…”

Ceres: Astrobiological Target and Possible Ocean World

“…According to Ruiz et al (2007), diapirs themselves could create transient habitable zones and/or reactivate dormant ones by warming the surrounding ice for hundreds of thousands of years. The same could be said for sills and fractures containing briny cryomagmas.…”

Predicting what extra-terrestrials will be like: and preparing for the worst

“…Just such an approach, of using terrestrial analogues to explore the potential habitation space, was employed by Marion et al [30] in the context of Europa. While the extreme cold of the surface and the intense impinging radiation suggest an environment well beyond tolerance of the hardiest organism, the strong likelihood of a deep ocean (possibly circulating [31] and with a complex chemistry [32]) residing beneath a dynamic ice shell (with thermal diapirism [33]) arguably makes this moon the priority target in the search for extra-terrestrial life. Yet neglecting the huge challenges in sampling even the cryosphere of Europa, our search for Europan life might still end in disappointment.…”