Can endogenic CO2 inflate radiolytic H2O2 in Europa’s Chaos?

Recent JWST observations reveal a higher abundance of endogenic CO₂ at Tara Regio, a prominent leading hemisphere chaos (Villanueva et al., 2023; Trumbo and Brown, 2023). Prior findings from Keck also show an excess of H₂O₂ in the same region (Trumbo et al., 2019). Could the emplacement of the ocean-derived CO₂ onto Europa’s surface influence radiolytic chemistry to boost peroxide yields in these enigmatic chaos regions? Increased H₂O₂ at fractured chaos terrains where ocean-surface exchange is more likely is exciting from a habitability stance, as it may facilitate oxidant delivery to the subsurface ocean.

We present laboratory results that show H₂O₂ synthesis increases by 2-3 folds in the presence of trace amounts of CO₂ (< 3 %) when compared to radiolysis of pure water ice. We also discuss correlations between CO₂ and H₂O₂ abundances in the JWST datasets to determine whether Europa’s endogenous CO₂ indeed conspires to inflate H₂O₂ at Tara Regio and possibly other chaos terrains. These JWST observations combined with emerging laboratory measurements set the stage for detailed mapping of CO₂ (via its 2.7 and ~4.23-4.29 µm absorptions) and H₂O₂ (via its 3.5 µm absorption) with MISE (Europa Clipper) and MAJIS (JUICE) at unprecedented spatial resolution.

References:

• Villanueva, G. L. et al., (2023) Science, 381, 1305–1308 
• Trumbo, S. K and Brown, M. E. (2023) Science, 381, 1308–1311
• Trumbo, S. K. et al. (2019) Astronomical Journal, 158, 127