[meteorite-list] The Fountains of Enceladus

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Nov 28 17:27:01 2005
Message-ID: <200511282225.jASMPVt21882_at_zagami.jpl.nasa.gov>

http://ciclops.org/view_event.php?id=45

The Fountains of Enceladus
Cassini Imaging Team
November 28, 2005

In a wonderful start to the Holiday season, Cassini imaging
scientists are delighted by recent sightings of fountain-like
plumes towering above Saturn's moon Enceladus. A fine spray of
small, icy particles, emanating from the warm, geologically unique
province surrounding the south pole of Enceladus and believed now
to supply the material comprising Saturn's E ring, was first
observed in images taken back on Jan. 16, 2005. Images of a
crescent Enceladus returned by Cassini this past weekend show
multiple plumes in striking detail. Stay tuned for future
announcements on the sightings of the Enceladus plumes.

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http://ciclops.org/view.php?id=1652

Spray Above Enceladus

A fine spray of small, icy particles emanating from the warm,
geologically unique province surrounding the south pole of Enceladus was
observed in a Cassini narrow-angle camera image of the crescent moon
taken on January 16, 2005.

Taken from a high phase angle of 148 degrees - a viewing geometry in
which small particles become much easier to see - the plume of material
becomes more apparent in images processed to enhance faint signals.

Imaging scientists have measured the light scattered by the plume's
particles to determine their abundance and fall-off with height. Though
the measurements of particle abundance are more certain within 100
kilometers (60 miles) of the surface, the values measured there are
roughly consistent with the abundance of water ice particles made by
other Cassini instruments (reported in September, 2005) at altitudes as
high as 400 kilometers (250 miles) above the surface.

At present, it is not clear if the plume emanating from the south pole
arises because of water vapor escaping from warm ice that is exposed to
the surface, or because at some depth beneath the surface, the
temperatures are hot enough for water to become liquid which then, under
pressure, escapes to the surface like a cold Yellowstone geyser.

The image at left was taken in visible green light. A dark mask was
applied to the moon's bright limb in order to make the plume feature
easier to see.

The image at right has been color-coded to make faint signals in the
plume more apparent. Images of other satellites (such as Tethys and
Mimas) taken in the last 10 months from similar lighting and viewing
geometries, and with identical camera parameters as this one, were
closely examined in order to demonstrate that the plume towering above
Enceladus' south pole is real and not a camera artifact.

The images were acquired at a distance of about 209,400 kilometers
(130,100 miles) from Enceladus. Image scale is about 1 kilometer (0.6
mile) 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 Cassini-Huygens mission for NASA's Science Mission
Directorate, Washington, D.C. The imaging team consists of scientists
from the US, England, France, and Germany. The imaging operations center
and team lead (Dr. C. Porco) are based at the Space Science Institute in
Boulder, Colo.

For more information about the Cassini-Huygens mission, visit
http://saturn.jpl.nasa.gov and the Cassini imaging team home page,
http://ciclops.org

Credit: NASA/JPL/Space Science Institute
Released: November 28, 2005 (PIA 07760)

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http://ciclops.org/view.php?id=1688

Fountains of Enceladus

Recent Cassini images of Enceladus at high phase show the fountain-like
sources of the fine spray of material that towers above the south polar
region of Enceladus. The image was taken looking more or less broadside
at the 'tiger stripe' fractures observed in earlier Enceladus images and
shows discrete and small-scale plumes above the limb of the moon.

The color-coded image at right was processed to enhance faint signals,
making contours in the plume of material even more apparent. The greatly
enhanced and colorized image shows the enormous extent of the fainter,
larger-scale component of the plume.

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 Cassini-Huygens mission for NASA's Science Mission
Directorate, Washington, D.C. The imaging team consists of scientists
from the US, England, France, and Germany. The imaging operations center
and team lead (Dr. C. Porco) are based at the Space Science Institute in
Boulder, Colo.

For more information about the Cassini-Huygens mission, visit
http://saturn.jpl.nasa.gov and the Cassini imaging team home page,
http://ciclops.org

Credit: NASA/JPL/Space Science Institute
Released: November 28, 2005 (PIA 07758, 07759)
Received on Mon 28 Nov 2005 05:25:31 PM PST