(Electrically Charged Particles Found in Enceladus’ Plumes)
http://www.universetoday.com/2009/04/21 ... us-plumes/
Regards,The spectrometer on Cassini, the Cassini Plasma Spectrometer (CAPS) discovered a surprise: the ice particles are electrically charged.
The CAPS instrument is designed to detect charged gas (plasma), but its measurements in the plume revealed tiny ice grains whose signatures could only be present if they were electrically charged.
The particles have both positive and negative electrical charges, and the mix of the charges varied as the Cassini spacecraft crossed the plume.
Jones and Arridge suggest that the grains may be charged through so-called triboelectric processes, through bumping together in the vent below Enceladus’s surface before they emerge into the plume. [Framed hypothesis?]
“What are particularly fascinating are the bursts of dust that CAPS detects when Cassini passes through the individual jets in the plume” says Jones. “Each jet is split according to charge though”, adds Arridge, “Negative grains are on one side, and positive ones on the other”. [Double layers? Birkeland currents?]