Scientists See Formations Similar To Utah Sandstones
NASA's Mars Reconnaissance Orbiter has revealed hundreds of
small fractures exposed on the Martian surface that billions of
years ago directed flows of water through underground Martian
sandstone.
Researchers used images from the spacecraft's High Resolution
Imaging Science Experiment, or HiRISE, camera. Images of layered
rock deposits at equatorial Martian sites show the clusters of
fractures to be a type called deformation bands, caused by stresses
below the surface in granular or porous bedrock.
"Groundwater often flows along fractures such as these, and
knowing that these are deformation bands helps us understand how
the underground plumbing may have worked within these layered
deposits," said Chris Okubo of the US Geological Survey in
Flagstaff, AZ.
Visible effects of water on the color and texture of rock along
the fractures provide evidence that groundwater flowed extensively
along the fractures.
"These structures are important sites for future exploration and
investigations into the geological history of water and
water-related processes on Mars," Okubo and co-authors state in a
report published online this month in the Geological Society of
America Bulletin.
Deformation band clusters in Utah sandstones, as on Mars, are a
few meters or yards wide and up to a few kilometers or miles long.
They form from either compression or stretching of underground
layers, and can be precursors to faults. The ones visible at the
surface have become exposed as overlying layers erode away.
Deformation bands and faults can strongly influence the movement of
groundwater on Earth and appear to have been similarly important on
Mars, according to this study.
"This study provides a picture of not just surface water
erosion, but true groundwater effects widely distributed over the
planet," said Suzanne Smrekar, deputy project scientist for the
Mars Reconnaissance Orbiter at NASA's Jet Propulsion Laboratory in
Pasadena, CA. "Groundwater movement has important implications for
how the temperature and chemistry of the crust have changed over
time, which in turn affects the potential for habitats for past
life."
The recent study focuses on layered deposits in Mars' Capen
crater, approximately 70 kilometers (43 miles) in diameter and 7
degrees north of the equator. This formerly unnamed crater became
notable due to this discovery of deformation bands within it and
was recently assigned a formal name. The crater was named for the
late Charles Capen, who studied Mars and other objects as an
astronomer at JPL's Table Mountain Observatory in Southern
California and at Lowell Observatory in Flagstaff.
The HiRISE camera is one of six science instruments on the
orbiter. It can reveal smaller details on the surface than any
previous camera to orbit Mars. The orbiter reached Mars in March
2006 and has returned more data than all other current and past
missions to Mars combined.
The mission is managed by JPL for NASA's Science Mission
Directorate. JPL is managed for NASA by the California Institute of
Technology in Pasadena. Lockheed Martin Space Systems of Denver
built the spacecraft. The University of Arizona operates the HiRISE
camera, built by Ball Aerospace and Technology Corp. of Boulder,
CO.