02.08.2017 Mars Reconnaissance Orbiter Observes Changes
01.26.2017 Mono Lake
01.25.2017 'Wing' Dike of Hardened Lava in New Mexico
01.25.2017 Blade-Like Martian Walls Outline Polygons
01.23.2017 Spirit And Opportunity By The Numbers
01.10.2017 Mars 2020 Rover - Artist's Concept
01.06.2017 Earth and Its Moon, as Seen From Mars
12.13.2016 Now and Long Ago at Gale Crater, Mars
12.13.2016 Where's Boron? Mars Rover Detects It
11.15.2016 Schiaparelli Impact Site on Mars, Stereo
11.03.2016 Schiaparelli Impact Site on Mars, in Color
10.17.2016 MAVEN Captures Rapid Cloud Formation
10.17.2016 Mars' Nightside Atmosphere
10.17.2016 Ultraviolet Image Near Mars' South Pole
10.17.2016 Ultraviolet Mars Reveals Cloud Formation
10.05.2016 Dust Haze Hiding the Martian Surface in 2001
10.04.2016 Test of Lander Vision System for Mars 2020
10.03.2016 A Sharpened Ultraviolet View of Mars
10.03.2016 Curiosity Self-Portrait at 'Murray Buttes'
10.03.2016 Butte 'M9a' in 'Murray Buttes' on Mars
09.19.2016 Ribbon Cutting
09.09.2016 Farewell to Murray Buttes (Image 5)
09.09.2016 Farewell to Murray Buttes (Image 4)
09.09.2016 Farewell to Murray Buttes (Image 3)
09.09.2016 Farewell to Murray Buttes (Image 2)
09.09.2016 Farewell to Murray Buttes (Image 1)
08.26.2016 Out-of-this-World Records
08.04.2016 Mars Rover Is New Social Media Game
08.04.2016 Mars Rover Social Media Game
08.02.2016 Artist Concept for RIMFAX
07.20.2016 Viking 40 Year Anniversary Artwork: Medal
07.18.2016 Mars 2020 Range Trigger
07.14.2016 NASA to Launch Mars Rover in 2020
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