Dunes Swarm Over Martian Plain: Big Pic
Detail of the barchan dunesNASA/JPL/University of Arizona
July 17, 2012 — We may be looking forward to Mars rover Curiosity kicking up some Martian dust when it lands inside Gale Crater on Aug. 5/6, but as the High-Resolution Imaging Science Experiment (HiRISE) camera aboard NASA's Mars Reconnaissance Orbiter (MRO) continues to show us, there's a lot more of Mars to explore.
This spectacular photograph shows what looks like a strange extraterrestrial campsite — little tents with their doors all facing the same way. Sadly, we're not looking at an aerial view of a Martian Woodstock Festival, it is in fact an impressive swarm of dunes spread over a north polar plain.
The dunes are created by a prevailing northwesterly wind blowing sand into 100-meter wide mounds called barchans over what appears to be a permafrost region. As described by HiRISE's Virginia Gulick, the dunes sit atop polygonal patterns and "numerous meter-scale boulders are strewn throughout the region." The plain is located at a latitude of over 73 degrees — higher than the landing site for NASA's 2008 Mars Phoenix lander at 68 degrees north.
a wide-field view of the plainNASA/JPL/University of Arizona
Barchan dunes are a known feature on the Martian surface, and there are similar examples on Earth. The pointed "horns" of barchans are created on the downwind slope of the dune that project from a sharp falloff of sand. The leading edge of the dune is typically more rounded and has a gentle slope. As time goes on, these dunes will likely be observed to drift with the wind.
Mars is far from being a static, geologically "dead" world. It may not play host to dramatic tectonic events that Earth is accustomed to, but the Red Planet's landscape continues to be shaped by winds and seasonal changes, ensuring that any future Mars traveler, be it robotic or human, will have a dynamic and fascinating world to explore.
HOWSTUFFWORKS: How the Great Sand Dunes were formed
-- by Ian O'Neill