Enceladus' hot springs

摘要

Many planetary bodies are thought to have produced hydrothermal activity - interactions between water and rock - as a result of hot-water circulation during the early stages of the Solar System, but Earth was the only one known to be sustaining such activity today. Then, in 2005, the Cassini spacecraft discovered eruptions of water vapour and ice emanating from long, warm fractures on the south pole of Saturn's moon Enceladus. The detection of salted, icy grains in Enceladus' erupting plume clearly pointed to an ocean environment below its icy crust and to the leaching of rocks by warm water, at least in the past. On page 207 of this issue, Hsu et al. report hints of presently active hydrothermal processes on Enceladus.