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06.01.2017 Diagram of Lake Stratification on Mars
05.22.2017 NASA's Mars 2020 Rover Artist's Concept #1
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04.20.2017 Chemical Laptop Team
04.20.2017 Subcritical Water Extractor
04.20.2017 Chemical Laptop
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03.29.2017 A Decade of Compiling the Sharpest Mars Map
03.21.2017 Break in Raised Tread on Curiosity Wheel
03.17.2017 COBALT/JPL team
03.09.2017 Back-to-Back Martian Dust Storms
02.27.2017 Swirling Dust in Gale Crater, Mars, Sol 1613
02.27.2017 Dust Devil Passes Near Martian Sand Dune
02.27.2017 Sand Moving Under Curiosity, One Day to Next
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
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12.13.2016 Now and Long Ago at Gale Crater, Mars
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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
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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'
Signs of Fluids and Ice in Acidalia PlanitiaHiRISE image (PSP_001942_2310) shows a crater approximately 11 km (7 miles) in diameter, located in Acidalia Planitia, part of the Northern Plains. Several features in and around this crater are suggestive of fluids and ice at and near the surface.
The south-looking (or equator facing) walls of this crater are cut by numerous gullies such as the ones shown in this image's cutout (500 x 600 m or 550 x 650 yards), with well developed alcoves, sinuous channels, and terminal fan deposits. These gullies seem to originate at the same height, suggesting that the carving agent may have emanated from one single layer exposed in the crater's wall.
Contrastingly, no gullies are observed in the north-looking (or pole facing) wall of this crater. Terrestrial gullies very similar to the ones shown in this image are produced by surface water. The arrows in the cutout show fissures that may indicate detachment of surficial materials possibly held together by subsurface ice, sliding en masse down the crater's wall.
The muted topography of the crater and its surroundings, the relatively shallow floor (300 m or 330 yards), the convex slope of its walls-all are consistent with ice being present under the surface, mixed with rocks and soil. Ice would have acted as a lubricant, facilitating the flow of rocks and soils and hence smoothing landscape's features such as ridges and craters' rims.
The concentric and radial fissures in the crater's floor may indicate decrease of volume due to loss of underground ice. Piles of rocks aligned along these fissures and arranged forming polygons are similar to features observed in terrestrial periglacial regions such as Antarctica. Antarctica's features are produced by repeated expansion and contraction of subsurface soil and ice, due to seasonal temperature oscillations. The funnel-shaped depressions visible in the crater's floor could be collapse pits, further evidence of ice decay; alternatively, they could be smoothed-out impact craters.
Image Credit: NASA/JPL-Caltech/Univ. of Arizona