05.15.2017 From 'Tribulation' to 'Perseverance' on Mars
03.29.2017 A Decade of Compiling the Sharpest Mars Map
03.09.2017 Back-to-Back Martian Dust Storms
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
05.11.2015 Icy Wonderland
05.04.2015 Diverse Orbits Around Mars
03.27.2015 South Pole Spiders
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
Some Gullies on Mars Could Be Tracks of Sliding Dry IceThese examples of one distinctive type of Martian gullies, called "linear gullies," are on a dune in Matara Crater, seen at different times of year to observe changes. The observations support a new hypothesis that chunks of frozen carbon dioxide, also known as "dry ice," may create linear gullies. In early Martian spring at some latitudes, dry-ice blocks may glide down sandy slopes on self-generated cushions of sublimating carbon-dioxide gas, plowing the grooves as they go and sometimes leaving pits where they stop sliding and sublimate away.
The three images were taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, of a site at 49.4 degrees south latitude, 34.7 degrees east longitude. The top image is from Mars southern-hemisphere early summer. The middle image is from the start of spring not quite two Martian years later. The white arrow points out a frost block, which appears very bright against the defrosting dune surface. The bottom image is from later the same spring. Black arrows indicate regions where new channels and pits appeared during the intervening seasons since the top image was taken. The scale bar is 50 meters (55 yards).
The three images are excerpts from HiRISE observations catalogued as ESP_013834_1300 (taken July 9, 2009); ESP_029038_1305 ESP_029038_1305 (taken Oct. 6, 2012) and ESP_029961_1305 ESP_029961_1305 (taken Dec. 17, 2012).
The University of Arizona Lunar and Planetary Laboratory operates HiRISE, which 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 in Washington. Lockheed Martin Space Systems, Denver, built the orbiter.
Image Credit: NASA/JPL-Caltech/Univ. of Arizona