Tuesday, May 15, 2012

MRO Detects Dune Movement

The above animation present two alternating images of the same area of Martian sand dunes taken three years apart. The animation shows the movement of the dunes. If you have problems seeing the animation, visit this link: Image Credit: NASA/JPL-Caltech/Univ. of Arizona/JHU-APL

Images from NASA's Mars Reconnaissance Orbiter have revealed that movement in sand dune fields on the planet Mars occurs on a surprisingly large scale, about the same as in dune fields on Earth.

The discovery is unexpected for three reasons: (1) the Red Planet has a much thinner atmosphere than Earth, (2) the atmosphere is only about one percent as dense, and (3) the atmosphere's high-speed winds are less frequent and weaker than Earth's.

We know from other Mars missions that the planet has its share of dust storms -- just talk to the Mars Exploration Rover mission team. Even so, researchers have debated for years whether the sand dunes observed on Mars were mostly fossil features related to past climate, or were they were currently active. In the past two years, researchers used the High Resolution Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter (MRO) to detect and report sand dune movement.

The researchers now report that entire dunes as thick as 200 feet (61 meters) are moving as coherent units across the Martian landscape. Their study was published online May 9th by the journal Nature.

Researchers analyzed before-and-after images using a new software tool developed at the California Institute of Technology (Caltech) in Pasadena, California. The tool measured changes in the position of sand ripples, revealing that 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 the 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.

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.

Scientists calculate that if someone stood in the Nili Patera dunes and measured out a one-yard (one-meter) width, they would see more than two cubic yards (1,500 liters) of sand pass by in an Earth year, about as much as in a child's sand box.

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.

And now the instrument particulars...

The HiRISE camera provides unprecedented resolution in studying the Martian landscape. NASA's Jet Propulsion Laboratory, Pasadena, California, a division of Caltech, manages the Mars Reconnaissance Orbiter 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, Colorado.

For related images and more information about Mars Reconnaissance Orbiter, visit the mission home page:

To learn more about the study, visit the online home page of the journal Nature:

For more on NASA' Exploring Mars Program, visit the program home page:


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