The Cassini spacecraft captures this dual portrait of an apparently dead
moon and one that is very much alive. Tethys, in the foreground, shows no
signs of recent geologic activity. Enceladus, however, is covered in
fractures and faults -- near its south pole in particular -- and spews
icy particles into space from active vents.
Tethys' giant crater Odysseus lurks in the dark just west of the
terminator. North on the moons is up.
The image was taken in visible light with the Cassini spacecraft
narrow-angle camera on Nov. 29, 2005 at a distance of approximately
970,000 kilometers (600,000 miles) from Tethys (1,071 kilometers, or 665
miles across) and at a Sun-Tethys-spacecraft, or phase, angle of 122
degrees. Cassini was then 1.1 million kilometers (700,000 miles) from
Enceladus (505 kilometers, or 314 miles across). Image scale is 6
kilometers (4 miles) per pixel on Tethys (at left) and 7 kilometers (4
miles) per pixel on Enceladus (at right).
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 and its two onboard cameras were designed, developed and
assembled at JPL. The imaging operations center is based at the Space
Science Institute in Boulder, Colo.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at
http://ciclops.org.
