Wednesday

Icy moons of Jupiter and Saturn are of huge interest in the context of possible eco-systems below the ice shells. Here we supplemented Cassini's measurements of organics venting from Enceladus with ground-based searches for complex molecules. We discuss our detection of methanol with the IRAM 30 m telescope, where the gas velocity was significantly red-shifted (by 8 km/s) with respect to the moon's orbital velocity. A trailing gas cloud could be used to explain the detection, i.e. confined by Saturn’s magnetospheric interaction with Enceladus. The data agree with Cassini flyby measurements of plasma near the south pole of Enceladus, where electrons form a denser cloud and are redshifted with respect to Enceladus (i.e. trailing the moon). This unexpected result opens up new questions about how best to observe pristine chemistry of the vents, before reactions occur in the charged environment of the host planet - how close does in-situ sampling need to go, to detect true biomarkers of sub-surface organisms?