Sand dunes get blown about on Mars

New data from NASA’s Mars Reconnaissance Orbiter has revealed that sand dunes on Mars are not as static as they were once thought to be. Instead the wind whips across the sand creating ripples across the landscape, almost as if it were breathing life into the sand. The motion of the sand dunes is similar to places in Antarctica, and this level of activity on the red planet has proved to be surprising. The Martian atmosphere is much thinner than that of Earth, and the high-speed winds pack less of a punch and occur less often than they do on Earth. It was originally thought that the sand dune features evident on Mars were fossilised relics from an ancient climate, rather than being coupled with the modern weather. The High Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter has been monitoring sand dunes over the past two years, and has catalogued the movement of the dunes. This has allowed scientists to determine that dunes up to 61 metres thick are moving as almost single units across the ground. The study, which has just been published in the journal Nature, focussed on images of Nili Patera sand dune area, which is close to the equator. The California Institute of Technology (Caltech) developed new software which allowed the scientists to precisely study the sequence of images. The software can be used to measure the changes in ripple positions, and thus how fast the sand moves. "This exciting discovery will inform scientists trying to better understand the changing surface conditions of Mars on a more global scale," said NASA’s Doug McCuistion. "This improved understanding of surface dynamics will provide vital information in planning future robotic and human Mars exploration missions." Knowledge of the speed of the sand dune movement is important for studying erosion on Mars, as it allows the scientists to calculate the rate at which rocks get sanded down. "Our new data shows wind activity is indeed a major agent of evolution of the landscape on Mars," said Jean-Philippe Avouac from Caltech. "This is important because it tells us something about the current state of Mars and how the planet is working today, geologically." This new data will pave the way for understanding why so much of the Martian surface has been strongly eroded, and if this is a result of current or past processes.