[meteorite-list] Cassini's Radar And VIMS Instruments Eye Impact Crater On Titan

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri Apr 29 12:23:50 2005
Message-ID: <200504291623.j3TGNJf07219_at_zagami.jpl.nasa.gov>

http://www.spacedaily.com/news/cassini-05zs.html

Cassini's Radar And VIMS Instruments Eye Impact Crater On Titan
SpaceDaily
April 29, 2005

[image]
VIMS false-color image showing one of Titan's most prominent impact
craters. It shows the faint halo to be slightly bluer than surrounding
material. That the material is bluer than its surroundings, while also
being darker, suggests that the faint halo is somewhat different in
composition. This suggests that the composition of Titan?s upper crust
varies with depth, and various materials were excavated when the crater
was formed. Photo credit: NASA/JPL/University of Arizona.

Pasadena CA (JPL) - The Cassini spacecraft has seen a 50-mile-diameter
impact crater on Titan with different instruments on separate flybys,
giving scientists new information on impact-crater formation on
Saturn's giant moon.

They've released a composite image of one of Titan's most prominent
impact craters as previously seen by Cassini's radar and recently seen
by its Visual and Infrared Mapping Spectrometer (VIMS).

The radar image was taken during the Cassini spacecraft's Feb. 15, 2005
Titan flyby, and the VIMS images were taken during its April 16, 2005
Titan flyby, said Robert H. Brown of The University of Arizona, head of
the VIMS experiment.

Brown released the composite image at the European Geosciences Union
meeting in Vienna, Austria, on Monday (April 25).

The crater seen on Titan by both radar and VIMS is more than 50 times
larger than Meteor Crater in northern Arizona.

In radar, the crater and its ejecta blanket are bright. In radar,
brighter surfaces mean rougher terrains, or else terrains tilted towards
the radar. At VIMS infrared wavelengths, the crater appears dark and the
ejecta blanket is bright, showing that the crust on the crater floor is
different material than the ejecta.

"The composite image highlights the differences and similarities in how
two instruments see the same thing," Brown said. "It shows the power of
combining instruments when you are trying to understand objects in the
Saturnian system."

VIMS is essentially a camera <#> that takes pictures in 352 different
colors at the same time. The colors cover the visible spectrum and into
the infrared, or from three-tenths of a micron up to five and one-tenth
microns. (A micron is one millionth of a meter.) Scientists can identify
the chemical composition of the surfaces, atmospheres and rings of
Saturn and its moons using VIMS.

Cassini began a 4-year-or-more exploratory tour of the Saturn system in
July 2004. It has seen two impact craters on Titan so far.
Received on Fri 29 Apr 2005 12:23:18 PM PDT