Status Report

Mars Odyssey THEMIS Image: Poynting Crater Ejecta

By SpaceRef Editor

July 30, 2002

Filed under Daily Themis Pictures, Mars Odyssey THEMIS, US

Image Context:

Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team

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Located roughly equidistant between two massive volcanoes, the
approximately 60 km Poynting Crater and its ejecta have experienced an
onslaught of volcanic activity. Pavonis Mons to the south and Ascraeus
Mons to the north are two of the biggest volcanoes on Mars. They have
supplied copious amounts of lava and presumably, ash and tephra to the
region. This THEMIS image captures evidence for these volcanic
materials. The rugged mound of material that dominates the center of
the image likely is ejecta from Poynting Crater just 40 km to the west
(see MOLA context image). The textural features of this mound are
surprisingly muted, giving the appearance that the image is out of focus
or has atmospheric obscuration. But the surrounding terrain shows clear
textural details and the mound itself displays tiny craters and
protruding peaks that demonstrate the true clarity of the image. One
conclusion is that the ejecta mound is covered by a mantle of material
that could be related to its proximity to the big volcanoes. The tephra
and ash deposits produced by these volcanoes could easily accumulate to
a thickness that would bury any textural details that originally existed
on the ejecta mound. In contrast, the lava flows that lap up to the
base of the mound show clear textural details, indicating that they came
after the eruptive activity that mantled the ejecta mound. Given the
fact that any ejecta material is preserved at all suggests that the
impact that produced Poynting Crater postdated the major construction
phase of the volcanoes.

[Questions? Email images@themis.asu.edu]

[Source: ASU THEMIS Science Team]

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA’s Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA’s Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Image Credit: NASA/JPL/Arizona State University