CO2, SO, Hydrates, and Other Constituents on the Trailing and Anti-Jovian Hemispheres of Europa From Reprocessed Galileo/NIMS Measurements

The Near Infrared Mapping Spectrometer observations at wavelengths 0.7-5.3 μm of the Jovian moon Europa are being repro­cessed using information gained throughout and beyond the Galileo mission. Early analysis of these reprocessed data (a global observation of the anti-Jovian and trailing hemispheres at 47 km spatial resolution) show evidence of spectral features not or only weakly apparent before (e.g., Geophys. Res. Lett., submitted). These include strong absorption bands attributed to CO2 and SO (centered near 4.25 and 4.0 μm, respectively), as well as weaker bands, such as one attributed to H2O2 (near 3.5 μm). The strong hydrate bands, including at near 1.5 and 1.95 μm, are more clearly defined. The band depth distribution of the CO2 and the most well defined hydrate bands are strongly associated with the (endogenic) dark reddish regions on the surface. The SO is not strongly correlated with the CO2, but has a similar sparse distribution. We will continue this study looking at higher spatial resolution observations and higher spectral resolution observations of the same area from the same and other orbits of Galileo.