New Horizons Observes Io's Volcanic Activity
Abstract
During its Jupiter flyby in late February and early March 2007, New Horizons obtained the first close-up observations of Io since the last Galileo data in 2001. Observations included comprehensive mapping of surface albedo changes, plume activity, and volcanic thermal emission, providing the most comprehensive globally-uniform snapshot of Io volcanism to date. Notable new sites of volcanic activity included a large ongoing pyroclastic eruption at Lerna Regio (55 S, 290 W) and a high-temperature eruption at 22 N, 235 W that has produced negligible surface changes at New Horizons resolution ( 15 km) and may therefore be very new. Most remarkable was a very bright hot spot and associated 350 km high volcanic plume from the Tvashtar volcano (62 N, 122 W), which provided the most comprehensive view yet of a large Io plume, including a plume movie which provided the first direct observations of motion in an Io plume. Projected speeds of up to 0.7 km s-1 were seen. The plume's morphology and dynamics support non-ballistic models of large Io plumes and also suggest that most visible plume particles condense within the plume rather than being ejected from the source. Comparison of visible and near-IR images of Io in Jupiter eclipse implies that a non-thermal process, likely auroral emission from volcanic gases within tens of kilometers of the surface, is producing visible-wavelength emission from individual volcanoes near Io's sub-Jupiter and anti-Jupiter points. Near-IR emission from the brightest volcanoes indicates minimum magma temperatures in the 1150 - 1335 K range, consistent with basaltic composition.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #39
- Pub Date:
- October 2007
- Bibcode:
- 2007DPS....39.1505S