HiRISE Shows Ever-Changing Mars
Orbiting Mars anywhere from 125 to 186 miles above the surface, the UA's HiRISE camera has revealed a Red Planet that is anything but dead — at least in geological and climatic terms.
For HiRISE's 10-year anniversary, we show a few highlights of the changing Mars. For more information about where these images were taken and what they reveal, visit the HiRISE website. And read more aobut HiRISE on UANews.
Images: NASA/JPL/University of Arizona
Continuing Avalanches: Since HiRISE first started finding avalanches on Mars, we have continued searching for them in the most likely places: steep cliffs at the edges of the layered deposits at the north pole. These layers are exposed in the scarp face that cuts through them diagonally across this subimage. The bright, smoother material at the lower left is at the top of the cliff, and here we have caught another avalanche as it falls down the steep slope toward the upper right of the image. A large (approximately 600 feet across) cloud of reddish dust has been kicked up at the base of the scarp.
Where Science Fact Meets Fiction: This is where the ordeal began for Mark Watney, the hero of Andy Weir's best-selling novel "The Martian." Brought here by the "Ares 3" spacecraft, his team had to abort the ill-fated mission, and Watney started his amazing story of exploration and survival. The Ares 3 landing site is located in Acidalia Planitia, within driving distance from the Pathfinder lander and Sojourner rover.
Curiosity Trek: The Mars Science Laboratory, Curiosity, continues its exciting traverse of Mars. In an image acquired in September, it was exploring the boundary between two rock units: the light-toned Murray Formation and the overlying and darker-toned Stimson unit. We can clearly see the rover in a complex terrain marked by tonally varied rocks, which, on the surface, can correspond to the contact between rock units and dark sand.
Shifting Snow: The south polar residual cap (the part that lasts through the summer) is composed of carbon dioxide ice. Although the cap survives each warm summer season, it is constantly changing its shape because of sublimation of carbon dioxide from steep slopes and deposition onto flat areas. Repeated imaging with HiRISE revealed that over just four Mars years, the high-standing mesas shrunk to about half of their size, but the low areas between mesas filled in with new carbon dioxide material.
A Fresh Crater: This impact crater appears relatively recent, as it has a sharp rim and well-preserved ejecta. The steep inner slopes are carved by gullies and include possible recurring slope lineae on the equator-facing slopes. Fresh craters often have steep, active slopes, so this crater is being monitored for changes over time. The bedrock lithology is also diverse. The crater is a little more than 1 kilometer wide. Note: When we say “fresh,” we mean on a geological scale. The crater is quite old on a human scale.
Layers and Dark Dunes: The target of this observation is a circular depression in a dark-toned unit associated with a field of cones to the northeast. At the image scale of a Context Camera image, the depression appears to expose layers especially on the sides or walls of the depression, which are overlain by dark sands presumably associated with the dark-toned unit.
Seasonal Flows in Valles Marineris: These brine flows are called recurring slope lineae because they fade and disappear during cold seasons and reappear in warm seasons, repeating this pattern every Martian year. The flows in this image emanate from the relatively bright bedrock and flow onto sandy fans, where they are remarkably straight, following linear channels. Valles Marineris contains more of these flows than everywhere else on Mars combined, and they are always active, although on changing slope aspects depending on the season. Future human explorers (and settlers?) will need water to drink, food to grow, oxygen to breathe and rocket fuel. Bringing all of that water from Earth would be extremely expensive, so using water on Mars is essential.
Wind at Work: Wind is one of the most active forces shaping Mars’ surface in today’s climate. The wind has carved the features called “yardangs,” one of many in this scene, and deposited sand on the floor of shallow channels between them. On the sand, the wind forms ripples and small dunes. In Mars’ thin atmosphere, light is not scattered much, so the shadows cast by the yardangs are sharp and dark.
Martian Twister: A towering dust devil casts a serpentine shadow over the Martian surface in this image. The scene is a late-spring afternoon in the Amazonis Planitia region of northern Mars. The view covers an area about four-tenths of a mile (644 meters) across. North is toward the top. The length of the dusty whirlwind's shadow indicates that the dust plume reaches more than half a mile (800 meters) in height. The plume is about 30 yards or meters in diameter.
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