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
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