May 24th, 2012
Econintersect: Mars has a much thinner atmosphere than does our own planet earth. That’s why the latest report from NASA’s Mars Reconnaissance Orbiter (MRO) is so surprising: Sand dunes on that planet are showing movement across the surface similar to those experienced by dunes on earth. Since movement of sand dunes is primarily driven by wind the movement on the surface of Mars is rather incredible. Yet such action is clearly shown in two years of images from MRO's High Resolution Imaging Science Experiment (HiRISE) camera.
Follow up:The results were summarized in a 22 May 2012 article in Scientific Computing., based on a 9 May 2012 paper preview published online by the journal Nature. From the Scientific Computing article:
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 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.
Here is the abstract of the full article published in Nature on May 17:
Strong and sustained winds on Mars have been considered rare, on the basis of surface meteorology measurements and global circulation models1, 2, raising the question of whether the abundant dunes and evidence for wind erosion seen on the planet are a current process. Recent studies3, 4, 5, 6 showed sand activity, but could not determine whether entire dunes were moving—implying large sand fluxes—or whether more localized and surficial changes had occurred. Here we present measurements of the migration rate of sand ripples and dune lee fronts at the Nili Patera dune field. We show that the dunes are near steady state, with their entire volumes composed of mobile sand. The dunes have unexpectedly high sand fluxes, similar, for example, to those in Victoria Valley, Antarctica, implying that rates of landscape modification on Mars and Earth are similar.
See more Mars photos from NASA at Space.com.
- NASA Mars Spacecraft Detects Large Changes in Martian Sand Dunes (Scientific Computing, 22 May 2012)
- Earth-like sand fluxes on Mars (N. T. Bridges, F. Ayoub, J-P. Avouac, S. Leprince, A. Lucas and S. Mattson, Nature, 17 May 2012, published online 9 May 2012)
- Mars’ sand dunes move surprisingly fast (Nola Taylor Redd, Space.com, Mother Nature Network, 9 May 2012)