Friday, June 24, 2011

Ice spray shooting out of Saturn moon points to a giant ocean lurking beneath its surface - 23rd June 2011

Scientists have collected the strongest evidence yet that Saturn moon Enceladus has a large saltwater ocean lurking beneath its surface.

Samples of ice spray shooting out of the moon have been collected by the Nasa's Cassini spacecraft during one of its frequent Saturn fly-bys.

The plumes shooting water vapor and tiny grains of ice into space were originally discovered emanating from Enceladus - one of 19 known moons of Saturn - by the Cassini spacecraft in 2005.

They were originating from the so-called 'tiger stripe' surface fractures at the moon's south pole and apparently have created the material for the faint E Ring that traces the orbit of Enceladus around Saturn.

During three of Cassini's passes through the plume in 2008 and 2009, the Cosmic Dust Analyser (CDA) on board measured the composition of freshly ejected plume grains.

The icy particles hit the detector's target at speeds of up to 11miles-per-second, instantly vaporising them. The CDA separated the constituents of the resulting vapor clouds, allowing scientists to analyse them.

The ice grains found further out from Enceladus are relatively small and mostly ice-poor, closely matching the composition of the E Ring. Closer to the moon, however, the Cassini observations indicate that relatively large, salt-rich grains dominate.

Lead researcher Frank Postberg, of the University of Heidelberg in Germany, said: 'There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across all the tiger stripes other than the salt water under Enceladus' icy surface.' Read More