Hydrogen Availability In The Europan Subsurface

The identification of a subsurface ocean beneath Europa's icy crust [1] has indicated that Europa may be able to support life and over the next decade, two spacecraft, ESA's JUICE and NASA's Europa Clipper, will head to the Jovian system to evaluate this. To inform the interpretation of data returned

from those missions, it is critical to understand the potential processes that might be operating within the Europa subsurface, and that might be influenced by microbial life. Hydrogen is a key component in oxidation-reduction reactions used by microbes to obtain energy [2], and it may have played a significant role in the emergence of life of Earth [e.g., 3]. On Europa, hydrogen

may be produced through water-rock interactions at the ocean floor, which also generate secondary minerals and modify the local chemical environment. However, computer modelling of Europa's ocean has suggested it would also contain high concentrations of carbon [4, 5], which independent investigations have shown could affect secondary mineral formation and the production of hydrogen

[6,7]. This, in turn, would influence the energy available to for potential life. This project aims to explore the influence a carbon-rich ocean would have on water-rock interactions at the Europa silicate-ocean interface, and its influence on habitability. It will combine computer modelling and laboratory experiments to examine the production of hydrogen under simulated

Europan conditions and determine the influence of this on the energy available to support microbial life.