Martian Sand Dunes May Be Migrating

A new series of observations from Martian orbit have brought up another one of the Red Planet's mysteries. Scientists have noticed that, at some locations, sand dunes are actively moving under the influence of strong winds, constantly changing their location. Conversely, at other locations, the same dunes have remained completely still for the past 100,000 years or so. According to the research team, Martian winds apparently have a selective approach to influencing dunes and ripples across the entire planetary surface. This line of investigation dates back more than a decade, experts at the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California, say.

The new conclusions are based on datasets collected by the Resolution Imaging Science Experiment (HiRISE) camera, on the NASA Mars Reconnaissance Orbiter. The spacecraft has been in Martian orbit for more than four years, and has recently sent its 100 terabyte of data. The images that laid the foundation for the new study were collected as far back as 2007, with older and newer sets being compared to each other to assess potential differences. Full details of the work were presented in two, independent papers near Houston this week, at the 41st Lunar and Planetary Sciences Conference.

One of the studies was focused on the Nili Patera area of Mars' northern hemisphere. It was conducted by G. d'Annunzio University International Research School of Planetary Sciences expert Simone Silvestro and his colleagues. The team saw significant changes in the dispositions of the dunes and their ripples. These features migrated by about 7 feet, or 2 meters, each. “The dark dunes in this part of Mars are active in present-day atmospheric conditions. It is exciting to have such high-resolution images available for comparisons that show Mars as an active world,” the team leader says.

The second paper was produced by experts at JPL, who were led by Matthew Golombek. Their study was focused on a region of Mars where the rover Opportunity has been conducting its activities for the past six years, called Meridiani Planum. The group looked at an area about 23 square kilometers (9 square miles) in size, using both HiRISE and Opportunity images. “HiRISE images are so good, you can tell if a crater is younger than the ripple migration. There's enough of a range of crater ages that we can bracket the age of the most recent migration of the ripples in this area to more than 100,000 years and probably less than 300,000 years ago,” the expert says.

“The more we look at Mars at the level of detail we can now see, the more we appreciate how much the planet differs from one place to another,” says the principal investigator of the HiRISE camera, University of Arizona in Tucson professor Alfred McEwen.