The Phenomena of the Martian Sand Dunes—Part II
The first sand dune seen on Mars was in 1972, when NASA’s Mariner 9 spacecraft showed us the fascinating and smooth shape of beauty, with the Mariner 9 transmitting data and images for about a year–images never seen before. When Mariner 9 arrived on Mars they had arrived during a huge dust storm, to the point that NASA ground controllers commanded it to wait for the storm to subside, revealing at its end a planet that was entirely unexpected—gigantic volcanoes and a grand canyon spread over 3,000 miles laced with ancient riverbeds.
Dark streaks revealed recent avalances of sand on the frost-covered slopes of the sand dune, on their steep down-wind “slip face” sides. The darkened sand streaks can never be more than eleven months old at the viewing, as they are superposed upon the brighter frost—therefore the streaks can be only as old as the frost. Because of this, scientists theorize that dunes with such markings can be active when they contain such streaks, with a year on Mars parallel to 669 days on Earth.
The reason scientists study the Martian sand dunes and their activity is to better understand how the wind of the red planet moves sediments around, and how long it takes for windblown sand to erode the rocks and their surfaces. With images from the Mars Global Surveyor (MGS) and its MOC camera, this has become easier when we can view images that appear like chocolate kiss drops on the planet’s surface.
The wind on Mars are able to blow up to 100 km/hr, large enough to engulf the entire planet. The sand dunes are continuously traveling across the planet because there are no surface water and plants to keep the dust and sand in place. At one time, the Planetary Society had put in place a microphone project, place in the Martian Polar Lander for those on Earth to hear the winds of Mars but the lander did not land safely. But the sand dunes near Moses Lake and Pasco, Washington, are similar to the Hebes Chasma area on Mars with its shifting sand dunes. When the wind loses its force or velocity, the sand particles are then redeposited, while over time the pile becomes bigger until it eventually becomes a sand dune.
This entry was posted on Sunday, April 27th, 2008 at 11:28 am and is filed under Mission Objectives, Space Agency News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
