HiRISE | Science in Motion

Science in Motion
For a view of refereed articles using HiRISE data, click here.

Seasonal Flows on Warm Martian Slopes
Alfred S. McEwen, Lujendra Ojha, Colin M. Dundas, Sarah S. Mattson, Shane Byrne, James J. Wray, Selby C. Cull, Scott L. Murchie, Nicolas Thomas, Virginia C. Gulick

Abstract
Water likely flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5-5 m), relatively dark markings on steep (25°-40°) slopes; repeat MRO/HiRISE images show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in rare locations. RSL appear and lengthen in the late southern spring/summer from 48°S to 32°S latitudes favoring equator-facing slopes--times and places with peak surface temperatures from ~250-300 K. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.

Science: Is Mars Weeping Salty Tears?
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Seasonal Erosion and Restoration of Mars’ Northern Polar Dunes
C. J. Hansen, M. Bourke, N. T. Bridges, S. Byrne, C. Colon, S. Diniega, C. Dundas, K. Herkenhoff, A. McEwen, M. Mellon, G. Portyankina, and N. Thomas

Abstract
Despite radically different environmental conditions, terrestrial and Martian dunes bear a strong resemblance, indicating that the basic processes of saltation and grainfall (sand avalanching down the dune slipface) operate on both worlds. Here we show that Martian dunes are subject to an additional modification process not found on the Earth: springtime sublimation of Mars’ CO2 seasonal polar caps. Numerous dunes in Mars’ north polar region have experienced morphological changes within a Mars year, detected in images acquired by the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO). Dunes show new alcoves, gullies, and dune apron extension. This is followed by remobilization of the fresh deposits by the wind, forming ripples and erasing gullies. The widespread nature of these rapid changes, and the pristine appearance of most dunes in the area, implicates active sand transport in the vast polar erg in Mars’ current climate.

Full article in Science
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Observations in this article
PSP_007962_2635 | PSP_008968_2650 | PSP_009105_2640 | PSP_009324_2650 | ESP_015935_2640
ESP_016256_2635 | ESP_016546_2635 | ESP_016836_2635 | ESP_017768_2640 | ESP_017974_2650
PSP_010019_2635 | ESP_018036_2635

Discovery of Columnar Jointing on Mars
M.P. Milazzo, L.P. Keszthelyi, W.L. Jaeger, M. Rosiek, S. Mattson, C. Verba, R.A. Beyer, P.E. Geissler, A.S. McEwen, and the HiRISE Team

Abstract
We report on the discovery of columnar jointing in Marte Valles, Mars. These columnar lavas were discovered in the wall of a pristine, 16-km-diameter impact crater and exhibit the features of terrestrial columnar basalts. There are discontinuous outcrops along the entire crater wall, suggesting that the columnar rocks covered a surface area of at least 200 sq. km, assuming that the rocks obliterated by the impact event were similarly jointed. We also see columns in the walls of other fresh craters in the nearby volcanic plains of Elysium Planitia-Amazonis Planitia, which include Marte Vallis, and in a well-preserved crater in northeast Hellas.

Full article in Geology
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Observation cited in this article
PSP_005917_2020

Spring at the South Pole of Mars
C.J.Hansen, A. McEwen
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Observations in this presentation
PSP_005579_0935 | PSP_003730_0945 | PSP_003443_0980 | PSP_003364_0945 | PSP_003179_0945
PSP_003113_0940 | PSP_003087_0930 | PSP_002942_0935 | PSP_002651_0930 | PSP_002622_0945
PSP_002532_0935


A Closer Look at Water-Related Geologic Activity on Mars Alfred S. McEwen HiRISE images reveal (1) abundant boulders in surface units previously interpreted as fine-grained deposits from water or the air; (2) further evidence for water-carved gullies, although the most recent bright gully deposits could have been dry flows; and (3) evidence that recent large craters were the result of impact into volatile-rich ground. These results should help focus future exploration of Mars. Read the article Download the "Science" cover image Cover image (PSP_003583_1425) 4048 x 5082; 59 MB JPEG2000 of the cover image For IAS Client Viewer Flyover movie (QuickTime) 320 x 180 (2.3 MB) 480 x 270 (5.8 MB) 640 x 360 (11 MB) Original observation for the above image PSP_003583_1425 List of images cited in this paper TRA_000846_2475 PSP_001964_2275 PSP_001810_2175 PSP_002172_1410 PSP_002932_1445 PSP_001714_1415 PSP_001846_1415 PSP_001481_1875 PSP_001978_1445 PSP_003596_1435 PSP_004229_1435 PSP_001846_2390 PSP_001508_2400 PSP_002200_1380 PSP_002812_1330 PSP_003252_1425 PSP_003942_2120 PSP_001538_2035 PSP_002158_2035	Meter-scale Morphology of the North Polar Region of Mars Kenneth E. Herkenhoff With detailed images from the HiRISE camera, a dome of layered ice deposits on the north pole of Mars comes into sharper focus, showing evidence of recent mass wasting, flow and debris accumulation. Read the article Flyover movie (QuickTime) 320 x 180 (5.9 MB) 480 x 270 (17.6 MB) 640 x 360 (21.3 MB) Orignal observation for the above image PSP_001636_2760 List of Images cited in this paper TRA_000845_2645 TRA_000863_2640 PSP_001412_2650 PSP_001488_2665 PSP_001550_2640 PSP_001738_2670	Athabasca Valles, Mars: A Lava-Draped Channel System Windy L. Jaeger Athabasca Valles is a young 'outflow' channel system in the equatorial region of Mars. Most researchers agree that it was carved by catastrophic floods of water, and some believe that frozen floodwaters survive to this day on the channel floor. However, new HiRISE observations reveal that Athabasca Valles is entirely coated by a thin veneer of solidified lava. The lava poured from a fissure, filled the channels, and then drained downstream leaving behind a thin layer of hard rock to coat and preserve the channel system. Read the article JPEG2000 for the above image For the IAS Client Viewer Flyover movie (QuickTime) 320 x 180 (5.6 MB) 480 x 270 (9.6 MB) 640 x 360 (25.4 MB) Original observation for the above image PSP_003294_1985 List of Images cited in this paper PSP_001408_1900 Stereo pair PSP_001606_1900 and PSP_002226_1900 Stereo pair PSP_001540_1890 and PSP_002371_1890 Stereo pair PSP_002938_1890 and PSP_003083_1890 Stereo pair PSP_002661_1895 and PSP_003294_1895 Stereo pair PSP_002174_1875 and PSP_002292_1875