Major Eruption at Enceladus?
In the first half of 2004, as Cassini approach Saturn prior to SOI, UVIS detected a dramatic increase in the amount of atomic oxygen in the Saturnian system, centered near the orbit of Enceladus. At the time of the announcement, the increase in mass in the region, roughly equivalent to the total mass of the E ring, was attributed to the collision of two km-sized particles in the E ring. However, the UVIS principle investigator, Larry Esposito, stated at the CHARM telecon today that "the water vapor escaping from Enceladus is adequate to supply the atomic oxygen in the Saturn system detected by UVIS, and to re-supply Saturn's E ring." So, what do we make of these two pieces of data, the likelihood that Enceladus supplies the atomic oxygen in the Saturn system and this dramatic increase in atomic oxygen last year. The obvious mechanism would be a major eruption on Enceladus. During this eruption, tremendous amounts of dust and water vapor was pumped into the E ring and the Saturn system. Certainly a very interesting idea that hopefully the UVIS team is examining.