[meteorite-list] MRO Detects Large Changes in Martian Sand Dunes

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 9 May 2012 13:12:55 -0700 (PDT)
Message-ID: <201205092012.q49KCuHG004427_at_zagami.jpl.nasa.gov>

May 9, 2012

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

Geoff Brown
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
240-228-5618
geoffrey.brown at jhuapl.edu

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov

RELEASE: 12-152

NASA MARS SPACECRAFT DETECTS LARGE CHANGES IN MARTIAN SAND DUNES

WASHINGTON -- NASA's Mars Reconnaissance Orbiter (MRO) has revealed
that movement in sand dune fields on the Red Planet occurs on a
surprisingly large scale, about the same as in dune fields on Earth.

This is unexpected because Mars has a much thinner atmosphere than
Earth, is only about one percent as dense, and its high-speed winds
are less frequent and weaker than Earth's.

For years, researchers debated whether or not sand dunes observed on
Mars were mostly fossil features related to past climate, rather than
currently active. In the past two years, researchers using images
from MRO's High Resolution Imaging Science Experiment (HiRISE) camera
have detected and reported sand movement.

Now, scientists using HiRISE images have determined that entire dunes
as thick as 200 feet are moving as coherent units across the Martian
landscape. The study was published online today by the journal
Nature.

"This exciting discovery will inform scientists trying to better
understand the changing surface conditions of Mars on a more global
scale," said Doug McCuistion, director of NASA's Mars Exploration
Program in Washington. "This improved understanding of surface
dynamics will provide vital information in planning future robotic
and human Mars exploration missions."

Researchers analyzed before-and-after images using a new software tool
developed at the California Institute of Technology (Caltech) in
Pasadena. The tool measured changes in the position of sand ripples,
revealing the ripples move faster the higher up they are on a dune.

The study examined images taken in 2007 and 2010 of the Nili Patera
sand dune field located near the Martian equator. By correlating
ripples' movement to their position on the dune, the analysis
determined the entire dunes are moving. This allows researchers to
estimate the volume, or flux, of moving sand.

"We chose Nili Patera because we knew there was sand motion going on
there, and we could quantify it," said Nathan Bridges, a planetary
scientist at Johns Hopkins University Applied Physics Laboratory in
Laurel, Md., and lead author of the Nature paper. "The Nili dunes
also are similar to dunes in places like Antarctica and to other
locations on Mars."

The study adds important information about the pace at which blowing
sand could be actively eroding rocks on Mars. Using the new
information about the volume of sand that is moving, scientists
estimate rocks in Nili Patera would be worn away at about the same
pace as rocks near sand dunes in Antarctica, where similar sand
fluxes occur.

"Our new data shows wind activity is indeed a major agent of evolution
of the landscape on Mars," said Jean-Philippe Avouac, Caltech team
leader. "This is important because it tells us something about the
current state of Mars and how the planet is working today,
geologically."

Scientists calculate that if someone stood in the Nili Patera dunes
and measured out a one-yard width, they would see more than two cubic
yards of sand pass by in an Earth year, about as much as in a
children's sand box.

"No one had estimates of this flux before," said Bridges. "We had seen
with HiRISE that there was dune motion, but it was an open question
how much sand could be moving. Now, we can answer that."

Scientists will use the information to understand broader mysteries on
Mars, like why so much of the surface appears heavily eroded, how
that occurred, and whether it is a current process or it was done in
the past. Scientists can now point to sand flux as a mechanism
capable of creating significant erosion today on the Red Planet.

The HiRISE camera provides unprecedented resolution in studying the
Martian landscape. NASA's Jet Propulsion Laboratory manages MRO for
NASA's Science Mission Directorate in Washington. Lockheed Martin
Space Systems, Denver, built the spacecraft. HiRISE is operated by
the University of Arizona and was built by Ball Aerospace &
Technologies Corp., Boulder, Colo.

For related images and more information about MRO, visit:

http://www.nasa.gov/mro
        
-end-
Received on Wed 09 May 2012 04:12:55 PM PDT