Alfred McEwen wrote:The Hills in Ganges Chasma (ESP_054609_1720) (HiClip)
Ganges Chasma is in the northeast portion of Valles Marineris, and opens into outflow channels that flowed to the north.
Scattered hills on the canyon floor may be remnants of chaos terrain that formed from collapse of the canyon. Some of the bedrock has diverse colors as we see in the enhanced-color cutout.
Ingrid Daubar wrote:New Crater Blues (ESP_053006_1980) (HiClip)
This new impact was found by the Context Camera team (CTX), who asked HiRISE to take a high-resolution image. They estimated the impact happened between January 2012 and September 2016, because they have a picture from the THEMIS instrument without it before that time frame. These craters may be somewhere between two and four (Earth) years old, which is exceedingly young in geologic terms. Most of the craters we see on Mars (like others in this picture) are millions of years old.
The blue appearance is due to the intense blast of the impact moving around dust on the surface. That dust is usually light-toned and reddish in color compared to what’s beneath it. When you remove the dust, you’re left with a dark spot that can sometimes be blue in comparison to the redder surroundings. These features are prominent only around young impacts, because all the old craters get covered with dust again over time.
This blueish “blast zone” is very different than the exposed ice some new craters dig up. The shape, color, and brightness are distinct and tell scientists this is not ice.
Alfred McEwen wrote:Ice Block Avalanche (ESP_054663_2650) (HiClip)
HiRISE has been re-imaging regions first photographed in 2006 through 2007, six Mars years ago. This long baseline allows us to see large, rare changes as well as many smaller changes.
One of the most actively changing areas on Mars are the steep edges of the North Polar layered deposits. This image shows many new ice blocks compared to an earlier image in December 2006. An animation shows one example, where a section of ice cliff collapsed. The older image (acquired in bin-2 mode) is not as sharp as the newer one.
Alfred McEwen wrote:Lingering Frost (ESP_053806_2650) (HiClip)
The North Polar layered deposits comprise a thick stack of icy layers. Part of this image has lingering seasonal frost, which serves to accentuate those layers.
An additional rationale for this observation is to document new activity in scarp erosion.
Credit: NASA/JPL-Caltech/University of Arizona
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