Click on the image for
Annotated Version with Yellow Stars
Heat radiating from the entire length of 150 kilometer (95 mile)-long
fractures is seen in this best-yet heat map of the active south polar
region of Saturn's ice moon Enceladus. The warmest parts of the fractures
tend to lie on locations of the plume jets identified in earlier images,
shown in the annotated version with yellow stars. The measurements were
obtained by the Cassini spacecraft's Composite Infrared Spectrometer from
the spacecraft's close flyby of the moon on March 12, 2008.
Remarkably high temperatures, at least 180 Kelvin (minus 135 degrees
Fahrenheit) were registered along the brightest fracture, named Damascus
Sulcus, in the lower left portion of the image. For comparison, surface
temperatures elsewhere in the south polar region of Enceladus are below 72
Kelvin (minus 330 degrees Fahrenheit).
Heat is escaping from Enceladus' interior along these warm fractures,
dubbed "tiger stripes," which are also the source of the geysers that
erupt from the polar region. The infrared radiation was mapped at
wavelengths between 12 and 16 microns. The infrared data, shown in false
color, are superimposed on a grayscale image mosaic of the south pole
obtained by Cassini's cameras on July 14, 2005, during the previous close
Enceladus flyby. Numbers on the map indicate latitude and longitude.
This new view shows that at least three of the south polar fractures are
active along almost their full lengths—the fourth one, on the right,
was only partially covered by this scan. The level of activity varies
greatly along the fractures. The warmest parts of the fractures tend to
lie on locations of the plume jets identified in earlier images. The main
"tiger stripe" fractures are not the only sources of heat, however;
additional warm spots are seen in the upper right part of the scan. The
warm regions are probably concentrated within less than a few hundred
meters (a few hundred yards) of the fractures, and their apparent width in
this image results from the relatively low resolution of the infrared
data.
This map was made by scanning the south pole during the period from 16 to
37 minutes after closest approach to Enceladus, at a distance between
14,000 and 32,000 kilometers (about 8,700 and 20,000 miles) as Cassini
rapidly receded from its close (50-kilometer or 32-mile) flyby.
The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory,
a division of the California Institute of Technology in Pasadena, manages
the mission for NASA's Science Mission Directorate, Washington, D.C. The
Cassini orbiter was designed, developed and assembled at JPL. The
Composite Infrared Spectrometer team is based at NASA's Goddard Space
Flight Center, Greenbelt, Md.
For more information about the Cassini-Huygens mission, visit
http://saturn.jpl.nasa.gov/home/index.cfm. The composite infrared spectrometer
team homepage is http://cirs.gsfc.nasa.gov/.
