|
+ Play
Audio
|
+ Download Audio | +
Email to a friend | +
Join mailing list
September
21, 2007: 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 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.
Above:
A montage image of the "Seven Sisters"--seven dark
openings into cavenrous spaces on the slopes of Arsia Mons.
Researchers have nicknamed the features Dena, Chloe, Wendy,
Annie, Abby, Nikki and Jeanne. [More]
Evidence that the holes may be openings to cavernous spaces
comes from the temperature differences detected from infrared
images taken in the afternoon vs. 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 this discovery 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.
Above:
Each of the three images covers the same patch of Martian
ground centered on skylight "Annie," which has a
diameter about double the length of a football field. The
left panel shows an ordinary white light view of Annie; right
panels show infrared images in mid-afternoon (center) and
just before sunrise (right). [More]
"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 Jet Propulsion Laboratory manages Mars Odyssey and Mars
Reconnaissance Orbiter for the NASA Science Mission Directorate,
Washington. Arizona State University operates the Mars Odyssey's
Thermal Emission Imaging System. For additional information
about Mars Odyssey and the new findings, visit the Odyssey
mission home page.
SEND
THIS STORY TO A FRIEND
Production Editor:
Dr. Tony Phillips | Credit: Science@NASA
| More
information |
"The
key to finding these [skylights] 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.
NASA's
future: The
Vision for Space Exploration
|
|
