A NASA probe has spotted hundreds of small surface fractures
near Mars' equator that may have acted as underground natural plumbing to
channel groundwater billions of years ago.
Geologists compare the fractures in the sandstone rock
deposits on Mars to features called deformation bands on Earth, which can arise
from the influence of groundwater in the underground bedrock. The bands and
faults have strong influences on groundwater movement on Earth, and seem to
have played the same role on Mars. Other research has examined how surface
water from
rain or snow shaped the planet surface, but many agree that groundwater has
an equally important influence.
"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, a geologist with the U.S. Geological Survey in Flagstaff, Ariz.
who headed up a new study of the Martian fractures.
The observations, made by NASA's Mars Reconnaissance
Orbiter (MRO), showed how water has already changed the color and texture of
the Martian sandstone along the fractures. Okubo's report on the finding is
detailed online this month in the journal Geological Society of America
Bulletin.
"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 MRO at NASA's
Jet Propulsion Laboratory in Pasadena, Calif., who was not part of the study.
"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."
Okubo and his study coauthors looked to similar patterns
in Utah sandstones on Earth, where fractures are typically a few yards wide and
up to several miles long. Such cracks reveal themselves as the rock layers on
top erode away.
MRO found similar fractures in a 43-mile-wide (70-km-wide)
crater that sits just slightly north of the red planet's equator. Discovery of
the deformation bands within the crater prompted scientists to name it after
Charles Capen, a late astronomer who worked at observatories in Southern
California and Flagstaff, Ariz.
"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 stated in their study.
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