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02.08.2017 Mars Reconnaissance Orbiter Observes Changes
01.25.2017 'Wing' Dike of Hardened Lava in New Mexico
01.25.2017 Blade-Like Martian Walls Outline Polygons
01.06.2017 Earth and Its Moon, as Seen From Mars
11.15.2016 Schiaparelli Impact Site on Mars, Stereo
11.03.2016 Schiaparelli Impact Site on Mars, in Color
03.30.2016 Erisa Hines
03.30.2016 Buzz Aldrin
03.21.2016 For a Decade Orbiting Mars: One Recent View
03.09.2016 For a Decade Orbiting Mars: One Recent View
03.09.2016 Mars Reconnaissance Orbiter By the Numbers
03.01.2016 MRO sees Frosty Spring Slopes
02.12.2016 Women in Science
02.10.2016 Wind at Work
11.16.2015 Change Observed in Martian Sand Dune
10.05.2015 'The Martian' Story's Ares 4 Landing Site
10.05.2015 The Ares 3 Landing Site (Figure A)
09.30.2015 Avalanche Ho!
06.29.2015 Mars Exploration Zone Layout Considerations
06.17.2015 Active High-Latitude Dune Gullies
06.03.2015 Crisp Crater in Sirenum Fossae
05.20.2015 Sedimentary Rock Layers on a Crater Floor
05.20.2015 Honey, I Shrunk the Mesas
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05.04.2015 Diverse Orbits Around Mars
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03.27.2015 A Smile a Day....
03.25.2015 Pitted Landforms in Southern Hellas Planitia
03.12.2015 Curiosity Heading Away from 'Pahrump Hills'
02.18.2015 Lava Flow Near the Base of Olympus Mons
02.09.2015 Yardangs in Arsinoes Chaos, Mars
02.04.2015 Curiosity Rover at 'Pahrump Hills'
01.22.2015 Frost on Crater Slope
01.16.2015 Components of Beagle 2 Flight System on Mars
12.03.2014 An Enigmatic Feature in Athabasca Lava Flows
12.02.2014 NASA's Journey to Mars
Seasonal Changes in Northern Mars Dune FieldThree images of the same location taken at different times on Mars show seasonal activity causing sand avalanches and ripple changes on a Martian dune. Time sequence of the images progresses from top to bottom. Each image covers an area 285 meters (312 yards) by 140 meters (153 yards). The crest of a dune curves across the upper and left portions of the image.
The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter took these images. The site is at 84 degrees north latitude, 233 degrees east longitude, in a vast region of dunes at the edge of Mars' north polar ice cap. The area is covered by carbon-dioxide ice in winter but is ice-free in summer. The top and bottom images show part of one dune about one Mars year apart, at a time of year when all the seasonal ice has disappeared: in late spring of one year (top) and early summer of the following year (bottom). The middle image is from the second year's mid-spring, when the region was still covered by seasonal carbon-dioxide ice.
Spring evaporation of the seasonal layer of ice is manifested as dark streaks of fine particles carried to the top of the ice layer by escaping gas. The bottom of the ice layer, in contact with the dark ground, warms faster than the top of the ice does in the spring. Carbon-dioxide gas produced by the thawing of the bottom ice is temporarily trapped under the top ice. As the ice evaporates from the bottom, flow of gas under the ice destabilizes the sand on the dune and causes the sand to avalanche down the dune slipface. A before-and-after comparison of the dune shows new alcoves and extension of the debris apron on the slipface of the dune caused by descending grains of sand. New wind ripples appear on the debris apron.
The top image is a portion of the HiRISE observation catalogued as PSP_008867_2640, taken on June 17, 2008.
The middle image is a portion of the HiRISE observation catalogued as ESP_016779_2640, taken on Feb. 23, 2010.
The bottom image is a portion of the HiRISE observation catalogued as ESP_018427_2640, taken on July 2, 2010.
The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson. The instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is NASA's industry partner for the project and built the spacecraft.
Image Credit: NASA/JPL-Caltech/University of Arizona