Cassini Spots Potential Ice Volcano On Saturn Moon

"When we look at our new 3-D map of Sotra Facula on Titan, we are
struck by its resemblance to volcanoes like Mt. Etna in Italy, Laki
in Iceland and even some small volcanic cones and flows near my
hometown of Flagstaff," said Randolph Kirk, who led the 3-D mapping
work, and is a Cassini radar team member and geophysicist at the U.S.
Geological Survey (USGS) Astrogeology Science Center in Flagstaff, Ariz.

Scientists have been debating for years whether ice volcanoes, also
called cryovolcanoes, exist on ice-rich moons, and if they do, what
their characteristics are. The working definition assumes some kind
of subterranean geological activity warms the cold environment enough
to melt part of the satellite's interior and sends slushy ice or
other materials through an opening in the surface. Volcanoes on
Jupiter's moon Io and Earth spew silicate lava.

Some cryovolcanoes bear little resemblance to terrestrial volcanoes,
such as the tiger stripes at Saturn's moon Enceladus, where long
fissures spray jets of water and icy particles that leave little
trace on the surface. At other sites, eruption of denser materials
might build up volcanic peaks or finger-like flows. But when such
flows were spotted on Titan in the past, theories explained them as
non-volcanic processes, such as rivers depositing sediment. At Sotra,
however, cryovolcanism is the best explanation for two peaks more
than 3000 feet high with deep volcanic craters and finger-like flows.

"This is the very best evidence, by far, for volcanic topography
anywhere documented on an icy satellite," said Jeffrey Kargel, a
planetary scientist at the University of Arizona, Tucson. "It's
possible the mountains are tectonic in origin, but the interpretation
of cryovolcano is a much simpler, more consistent explanation."

Kirk and colleagues analyzed new Cassini radar images. His USGS group
created the topographic map and 3-D flyover images of Sotra Facula.
Data from Cassini's visual and infrared mapping spectrometer revealed
the lobed flows had a composition different from the surrounding
surface. Scientists have no evidence of current activity at Sotra,
but they plan to monitor the area.

"Cryovolcanoes help explain the geological forces sculpting some of
these exotic places in our solar system," said Linda Spilker, Cassini
project scientist at NASA's Jet Propulsion Laboratory in Pasadena,
Calif. "At Titan, for instance, they explain how methane can be
continually replenished in the atmosphere when the sun is constantly
breaking that molecule down."

Cassini launched Oct. 15, 1997, and began orbiting Saturn in 2004.
Saturn has more than 60 known moons, with Titan being the largest.
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency (ASI). JPL manages
the mission for NASA's Science Mission Directorate at the agency's
Headquarters in Washington.

The Cassini orbiter was designed, developed and assembled at JPL. The
radar instrument was built by JPL and ASI, working with team members
from the U.S. and several European countries. The visual and infrared
mapping spectrometer was built by JPL, with a major contribution by
ASI. The visual and infrared mapping spectrometer science team is
based at the University of Arizona, Tucson.

For more information about the Cassini mission, visit:

http://www.nasa.gov/cassini

Source: NASA

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