Dwayne Brown
Headquarters, Washington
202-358-1926
Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
Lori Stiles
University of Arizona, Tucson
520-626-4402
RELEASE: 07-43
NASA MARS ORBITER SEES EFFECTS OF ANCIENT UNDERGROUND FLUIDS
SAN FRANCISCO - Liquid or gas flowed through cracks penetrating
underground rock on Mars, according to a report based on some of the
first observations by NASA's Mars Reconnaissance Orbiter. These
fluids may have produced conditions to support possible habitats for
microbial life.
These ancient patterns were revealed when the most powerful telescopic
camera ever sent to Mars began examining the planet last year. The
camera showed features as small as approximately 3 feet across.
Mineralization took place deep underground, along faults and
fractures. These mineral deposits became visible after overlying
layers eroded throughout millions of years.
Chris Okubo, a geologist at the University of Arizona, Tucson,
discovered the patterns in an image of exposed layers in a Martian
canyon named Candor Chasma. The High Resolution Imaging Science
Experiment camera aboard the orbiter took the image in September
2006.
"What caught my eye was the bleaching or lack of dark material along
the fracture. That is a sign of mineral alteration by fluids that
moved through those joints," said Okubo. "It reminded me of something
I had seen during field studies in Utah, that is light-tone zones, or
'haloes,' on either side of cracks through darker sandstone."
"This result shows how orbital observations can identify features of
particular interest for future exploration on the surface or in the
subsurface or from sample return. The alteration along fractures,
concentrated by the underground fluids, marks locations where we can
expect to find key information about chemical and perhaps biologic
processes in a subsurface environment that may have been habitable,"
said Alfred McEwen, principal investigator for the camera at the
University of Arizona, Tucson.
The haloes visible along fractures seen in the Candor Chasma image
appear to be raised slightly relative to surrounding, darker rock.
This is evidence that the circulating fluids hardened the lining of
the fractures, as well as bleaching it. The harder material would not
erode as quickly as softer material farther from the fractures.
"The most likely origin for these features is that minerals that were
dissolved in water came out of solution and became part of the rock
material lining the fractures. Another possibility is that the
circulating fluid was a gas, which may or may not have included water
vapor in its composition," Okubo said.
Similar haloes adjacent to fractures show up in images that the
high-resolution camera took of other places on Mars after the initial
Candor Chasma image. "We are excited to be seeing geological features
too small to have been noticed previously," Okubo said.
"This publication is just the first of many, many to come. The
analysis is based on test observations taken even before the start of
our main science phase. Since then, Mars Reconnaissance Orbiter has
returned several terabits of science data, sustaining a pace greater
than any other deep space mission. This flood of data will require
years of study to exploit their full value, forever increasing our
understanding of Mars and its history of climate change," said
Richard Zurek, project scientist for the Mars Reconnaissance Orbiter
at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
Okubo and McEwen report these findings in the Feb. 16 edition of the
journal Science. Images showing the haloes along fractures are
available on the Web at:
http://www.nasa.gov/mission_pages/MRO/news/20070215.html
The Jet Propulsion Laboratory manages the orbiter mission for NASA's
Science Mission Directorate, Washington. Lockheed Martin Space
Systems, Denver, is the prime contractor for the project and built
the spacecraft. The University of Arizona operates the High
Resolution Imaging Science Experiment camera. Ball Aerospace and
Technology Corp., Boulder, Colo built the camera.
-end-
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