Name this crater

[neufer]

A 3-d view of a well-preserved and unnamed impact crater on Mars, as seen by the HiRISE camera on the Mars Reconnaissance Orbiter. NASA/JPL/University of Arizona. [url=http://www.uahirise.org/images/2012/details/cut/ESP_025450_1595.jpg]Click for high-resolution version.[/url]

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Incredible 3-D View Inside a Martian Crater
by Nancy Atkinson on February 3, 2012

<<This is why I always keep a pair of 3-D glasses by my computer. This well-preserved crater on Mars may look like just your average, run-of-the-mill impact crater in 2-D, but in 3-D, the sharply raised rim, the deep, cavernous crater body, and especially the steep crater walls will have you grabbing your armchairs so you don’t fall in. The image is courtesy of the HiRISE camera team from the Mars Reconnaissance Orbiter. This unnamed crater is about 6 or 7 kilometers wide from rim to rim. HiRISE took the image on New Year’s Eve 2011.

HiRISE principal investigator Alfred McEwen says that the camera has imaged hundreds of well-preserved impact craters on Mars ranging from 1 meter to more than 100 kilometers wide. What can the scientists learn from craters?

“These targets are of great interest for multiple reasons,” he said. “First, we want to better understand impact cratering, a fundamental surface process. Second, such craters often contain good exposures of bedrock in the steep walls and, if the crater is large enough, in the central uplift. Just like terrestrial geologists are attracted to good bedrock outcrops like road cuts, planetary geologists are attracted to well-preserved craters.

“Third, the steep slopes often reveal active processes, such as formation of gullies, boulder falls, and slope streaks that could form in a variety of ways. Some of these active processes could be related to water, since the crater may expose lenses of ice or salty water, or create deep shadows that trap volatiles, or expose salts that can extract water from the air.”

Plus, they are just plain wonderful to behold, especially in the resolution the HiRISE can obtain.>>

[bystander]

HiRISE: Another Well-Preserved Impact Crater (ESP_025450_1595)
http://asterisk.apod.com/viewtopic.php?f=29&t=27014

[neufer]

[b][color=#0000FF]At this location on Mars, overlapping of the moraines suggests 5 to 7 episodes of advance and retreat of the glaciers. Each time the glaciers dropped debris scraped up from the crust and deposited it as ice vaporized when the climate warmed just as on Earth. Credit: NASA[/color][/b]

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[b][color=#0000FF]An unnamed crater on in the Martian northern lowlands with with loop-shaped ridges interpreted as drop moraines left by retreating frozen carbon dioxide glaciers. The crater is about 22 miles across. Credit: NASA[/color][/b]

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Glaciers once plucked the valleys of Mars … and will again
Posted on February 3, 2012 by astrobob

<<If you’re driving across Minnesota, Wisconsin or Illinois and see a long, low ridge up ahead, there’s a fair chance it’s a moraine, or a pile of rocky debris along a lobe of a melting glacier. Glaciers also appear to have been at work on Mars. Recently, members of the Planetary Geomorphology Working Group of the International Association of Geomorphologists described “drop moraines” in three regions of Mars created by extinct glaciers made not of water but of dry ice. These cold-based or polar glaciers are nearly frozen to the bedrock. Drop moraines form only in the coldest environments when a glacier advances and then stabilizes for a time in one spot. Rocks carried down by the glacier drop out as the ice vaporizes directly from solid to gas instead of melting first into liquid. Voila! – drop moraines.

In the left picture, the loopy ridges of extinct lobes around the central peak of the crater suggest that the glacier that left them was about a thousand feet thick. Scientists hypothesize that the glaciers formed millions to tens of millions of years ago due a shift in the tilt of Mars polar axis. Mars’ axis swings through a large range – believed to vary from 11 to 49 degrees - due to the gravitational tugging effects of the other planets over the long haul of time.>>