Click on image for larger annotated version
This three-image mosaic is the highest resolution view yet obtained of
Enceladus' north polar region. The view looks southward over cratered
plains from high above the north pole of Enceladus.
Cassini's March 2008 flyby of Enceladus was designed to directly
investigate the ongoing plume activity at the moon's south pole, but the
path of the spacecraft allowed investigation of older evidence for
internal activity near the north pole.
Compared to much of the moon's southern hemisphere—the south polar
region in particular—the north polar region is much older and
covered with craters. These craters are captured at different stages of
disruption and alteration by tectonic activity and probably past heating
from below. Many of the craters seen here are sliced by small parallel
cracks that seem to be ubiquitous throughout the old cratered terrains on
Enceladus. The mosaic also shows a variety of impact crater shapes, some
with bowed-up floors and smaller craters within, very likely indicating
that the icy crust in this area was at some time warmer than at present.
While this conclusion was previously reached from NASA Voyager spacecraft
images, these new data provide a much more detailed look at the fractures
that modify the surface. This data will give a significantly improved
comparison of the geologic history at the satellite's north pole with that
at the south pole.
Two prominent craters in this view, Ali Baba and Aladdin (the two
overlapping craters near center), are among the largest craters known on
Enceladus.
Several areas of much younger terrain are visible in this mosaic,
including Samarkand Sulci, an area of disrupted terrain that runs
north-south at left of center, and the "leading hemisphere terrain," a
region, seen at right, filled with tectonic fractures, ridges and "ridged
terrain."
Samarkand Sulci slices through some prominent craters that were seen in
Voyager images. At that time, it was thought that the portions of the
craters that extend into Samarkand were completely destroyed by whatever
process formed Samarkand. However, Cassini images show remnants of the
crater rims that have survived. This new insight provides a benchmark for
measuring how tectonic processes modify older terrains, and will also help
imaging scientists develop a more accurate timeline for the geologic
history of these terrains.
Lit terrain seen here is on the Saturn-facing hemisphere of Enceladus (505
kilometers, or 314 miles across).
The image was taken in visible light with the Cassini spacecraft
narrow-angle camera on March 12, 2008. The view was acquired at a distance
of approximately 32,000 kilometers (20,000 miles) from Enceladus and at a
Sun-Enceladus-spacecraft, or phase, angle of 115 degrees. Image scale is
176 meters (577 feet) per pixel.
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/home/index.cfm.
The Cassini imaging team homepage is at http://ciclops.org.
