Movie Clip
Click on the image
The most prominent jets of vapor and icy particles emerging from the south
polar terrain of Saturn's moon Enceladus are shown here in graphical form
in a movie clip of a "rotating" Enceladus.
A mosaic constructed of images of Enceladus' southern hemisphere (see
PIA11126) from NASA's Cassini spacecraft imaging science
sub-system was projected onto a computer model of the moon to which vectors
indicating the direction of the jets were added.
About the Video
Reconstructing the Past on Enceladus
The video demonstrates two examples of the interpretation of tectonic spreading
along the “tiger stripe” fractures in the south polar terrain of Saturn’s moon
Enceladus. The first part of the video shows a simple example in which an old
relict tiger stripe is believed to have lost its tip after it was sheared off by tectonic
forces and pushed away from its parent by spreading. In the meantime, the
parent tiger stripe has managed to regenerate a replacement tip, probably by
the creation of new icy crust from upwelling soft ice. The orphaned "clone" now
sits by itself, connected to the parent only by two parallel fault lines. The movie
shows that, if the orphaned tiger stripe tip can be slid along the parallel faults
back into place on the parent rift, the fit is remarkably good. Striated material
between the clone and the replacement tip represents new icy crust material
that must have been created during the spreading process.
The second part of the video demonstrates how this video-reconstruction
technique can be used to infer a possible spreading history of the region
between two tiger stripes: Alexandria Sulcus and Cairo Sulcus. The process
begins by snipping-out and closing the gap that corresponds to Alexandria
Sulcus and its upraised flanks. The gap is closed by matching the remaining
right and left edges like a jigsaw puzzle. The closure is accomplished by
sliding along a prominent fault nearly perpendicular to one end of Alexandria.
This segment of the video is repeated four times with arrows that mark
previously offset features that come into alignment after Alexandria is closed.
Next, Cairo Sulcus is closed along a lower fault that is parallel to the one
along which Alexandria was closed. After the Cairo is removed, the closure
is continued along the same fault until all of the intervening terrain has been
removed. During this process, a mysterious 14-kilometer-sized elliptical
feature appears by matching a semi-circular feature that previously existed
on the right side of Cairo with the left side of an oval-shaped feature that exists
between Alexandria and Cairo. In this way, the gap between Cairo and
Alexandria can be closed completely, but there remains a length of the fault
that suggests even more spreading may have occurred. Closing the gap all
the way along this fault results in the reappearance of a feature that resembles
the elliptical structure seen earlier. This feature is perhaps a relict impact crater
or the surface expression of a rising warm diapir or icy convection cell.
The video was created based on images of the south pole of Enceladus taken
from this map, see PIA11126.
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.