[meteorite-list] Mars Odyssey Finds Possible Cave Skylights on Mars

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 21 Sep 2007 11:45:26 -0700 (PDT)
Message-ID: <200709211845.LAA02659_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2007-106

NASA Orbiter Finds Possible Cave Skylights on Mars
Jet Propulsion Laboratory
September 21, 2007

PASADENA, Calif. -- NASA's Mars Odyssey spacecraft has discovered
entrances to seven possible caves on the slopes of a Martian volcano.
The find is fueling interest in potential underground habitats and
sparking searches for caverns elsewhere on the Red Planet.

Very dark, nearly circular features ranging in diameter from about 100
to 250 meters (328 to 820 feet) puzzled researchers who found them in
images taken by NASA's Mars Odyssey and Mars Global Surveyor orbiters.
Using Mars Odyssey's infrared camera to check the daytime and nighttime
temperatures of the circles, scientists concluded that they could be
windows into underground spaces.

Evidence that the holes may be openings to cavernous spaces comes from
the temperature differences detected from infrared images taken in the
afternoon and in the pre-dawn morning. From day to night, temperatures
of the holes change only about one-third as much as the change in
temperature of surrounding ground surface.

"They are cooler than the surrounding surface in the day and warmer at
night," said Glen Cushing of the U.S. Geological Survey's Astrogeology
Team and of Northern Arizona University, Flagstaff, Ariz. "Their thermal
behavior is not as steady as large caves on Earth that often maintain a
fairly constant temperature, but it is consistent with these being deep
holes in the ground."

A report of the discovery of the possible cave skylights by Cushing and
his co-authors was published online recently by the journal Geophysical
Research Letters.

"Whether these are just deep vertical shafts or openings into spacious
caverns, they are entries to the subsurface of Mars," said co-author Tim
Titus of the U.S. Geological Survey in Flagstaff. "Somewhere on Mars,
caves might provide a protected niche for past or current life, or
shelter for humans in the future."

The discovered holes, dubbed "Seven Sisters," are at some of the highest
altitudes on the planet, on a volcano named Arsia Mons near Mars'
tallest mountain.

"These are at such extreme altitude, they are poor candidates either for
use as human habitation or for having microbial life," Cushing said.
"Even if life has ever existed on Mars, it may not have migrated to this
height."

The new report proposes that the deep holes on Arsia Mons probably
formed as underground stresses around the volcano caused spreading and
faults that opened spaces beneath the surface. Some of the holes are in
line with strings of bowl-shaped pits where surface material has
apparently collapsed to fill the gap created by a linear fault.

The observations have prompted researchers using Mars Odyssey and NASA's
newer Mars Reconnaissance Orbiter to examine the Seven Sisters. The goal
is to find other openings to underground spaces at lower elevations that
are more accessible to future missions to Mars.

"The key to finding these was looking for temperature anomalies at night
-- warm spots," said Phil Christensen of Arizona State University,
Tempe, principal investigator for the Thermal Emission Imaging System on
Mars Odyssey. That instrument produced both visible-light and infrared
images researchers used for examining the possible caves.

"No other instrument at Mars could give the thermal information crucial
to this research," said the project scientist for Mars Odyssey, Jeffrey
Plaut of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This is a
great example of the exciting discoveries Odyssey continues to make."
Mars Odyssey reached Mars in 2001, years before any of the other
spacecraft currently examining the planet. Its predecessor, Mars Global
Surveyor, ended its mission last year.

Mars Odyssey is managed by JPL, a division of the California Institute
of Technology, Pasadena, for NASA's Science Mission Directorate,
Washington. Lockheed Martin Space Systems, Denver, is the prime
contractor for the project and built the spacecraft. The orbiter's
Thermal Emission Imaging System was developed by Arizona State
University, Tempe, in collaboration with Raytheon Santa Barbara Remote
Sensing, Santa Barbara, Calif., and is operated by Arizona State
University. For additional information about Mars Odyssey and the new
findings, visit: http://www.nasa.gov/mission_pages/odyssey.

------------------------------------------------------------------------

Media contact: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown
Headquarters, Washington
202-358-1726

2007-106
Received on Fri 21 Sep 2007 02:45:26 PM PDT