Step aside Enceladus, you might not be the only moon orbiting Saturn with eruptions of water ice. Two of your Saturnian sisters, Tethys and Dione could have similar ice geysers, contributing their particles to Saturn's rings.
Data gathered by NASA's Cassini spacecraft have led researchers to believe that these two icy moons are also geologically active, and maybe even volcanic. The research was published in this week's issue of the journal Nature.
Cassini didn't actually see particles coming off of Dione and Tethys as it did with Enceladus. Instead, the spacecraft detected electrically charged gas, called plasma, that could be traced back to the orbits of the icy moons.
Jim Burch, a team member of the Cassini Plasma Spectrometer at the
Southwest Research Institute, noticed an interesting shape in the distribution of this gas.
And it led him back to Dione and Tethys.
If these moons are indeed the source of this material, that means their interiors haven't become geologically dead, or they might be supplied by energy. The moons may experience a tidal flexing through their interaction with Saturn that keeps their interiors warmed up.
Unfortunately, Cassini isn't scheduled for any more flybys of Dione and
Tethys. Researchers will have to dig through the 2005 flyby images for hints of ice geysers. Surprisingly, data gathered by the Voyager and
Pioneer spacecraft hinted at this plasma decades ago. It might be that the plasma only occurs during a certain point of the moons' orbit around Saturn.
The next step will be search for actual particles in the vicinity that could be chemically linked to Dione and Tethys.
Oh, and hoping that Cassini mission scientists take this seriously enough to retarget the spacecraft's trajectory to give these moons another look.
