Widespread CO₂ and other non‐ice compounds on the anti‐Jovian and trailing sides of Europa from Galileo/NIMS observations

An observation at wavelengths 0.7–5.3 μ m of the anti‐Jovian and trailing sides of the moon Europa by the Near Infrared Mapping Spectrometer on the Galileo spacecraft has been reprocessed to reveal new details in the >3.0 μ m infrared spectrum. The revealed features include strong absorption bands centered at 4.25 and 4.0 μ m, attributed to CO 2 and SO 2 , as well as weaker bands, such as near 3.5 μ m attributed to H 2 O 2 . The calculated band depth distribution of both the CO 2 and SO 2 show that the CO 2 is strongly associated with the (possibly endogenic) dark (typically hydrate) regions on the surface, while the SO 2 is not strongly correlated with the CO 2 , but has a similar sparse distribution. The association of CO 2 with the hydrates may indicate a CO 2 ‐rich ocean that is a potential environment for autotrophic organisms that might thrive near the rock‐ocean interface, similar to the earliest life on Earth.