Geotimes
Web Extra:   Aug 20, 2001

A close look at Io volcanism

Last December, the NASA spacecrafts Galileo and Cassini snapped pictures of a new and enormous volcanic plume near the pole of Io, one of Jupiter's moons (see Geotimes, December 2000). The Galileo camera spied a bright lake of lava at the site, and the Cassini camera, using an ultraviolet filter, was able to detect a plume of erupting gaseous material reaching nearly 400 kilometers above the surface.
     During an Aug. 5 flyby, Galileo captured a series of six pictures of Tvashtar Catena, the volcanic feature from which the plume originated. So far there is no direct evidence that the site is still active, but if the formation is experiencing any lava flows or eruptions, scientists will hopefully see it when they review Galileo footage this week and  will have acquired the closest look yet at active volcanism on Io, understood to be the most geologically active body in the solar system.
    Galileo also took pictures of Tvashtar from greater range. These more distant, wider angle views of the area provide context, with a resolution of about 52 meters (170 feet). Once the Galileo data have been analyzed, scientists hope to learn more about the composition of Tvashtar-region surface materials, and, if the plume is indeed active, the composition of plume gasses.

Emily D. Johnson

Visit the Jet Propulsion Laboratory Web site for more:  www.jpl.nasa.gov/galileo/news/thiswk.html.



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