Saturn's tides control Enceladus' plume

Abstract

Data obtained by the Cassini spacecraft show that the plume of ice particles at the south pole of Saturn's moon Enceladus is four times brighter when the moon is farthest away from the planet than when it is closest. See Letter p.182 Between 2005 and 2012 the Cassini spacecraft's Visual and Infrared Mapping Spectrometer (VIMS) obtained 252 images of the plume of water vapour and ice particles emitting from near the south pole of Saturn's moon Enceladus. These images have been analysed with a view to establishing the nature of the geological forces driving the plume. The authors show that as Enceladus moves along its elliptical orbit, the brightness of the plume peaks — and larger amounts of material join the plume — when the moon is furthest from Saturn. This is consistent with a model in which tidal forces have an important role in controlling plume activity, perhaps by changing the width of the conduits between the surface and various underground reservoirs supplying the fissures through which the plume emerges.