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The breakup of a Martian glacier

The breakup of a Martian glacier
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken on January 29, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label a “contact” in the glacier country in the northern mid-latitudes of Mars.

The contact is clearly the region of breakup in the middle of the picture. To the right the surface is whole and very smooth. As we move to the left that surface begins to show cracks and holes until those holes and cracks eliminate that surface entirely, revealing a lower layer that is soft-looking and stippled.

In other words, this is the edge of a glacier, and is the place in which it is breaking up. Unlike Earth glaciers however this breakup process is entirely different.

Overview map

The white dot in Deuteronilus Mensae indicates the location of this glacial breakup. At 43 degrees north latitude, it is deep within the Martian 2,000-mile-long northern mid-latitude strip of chaos terrain I dub glacier country. Here, almost every picture shows glacial features.

This contact suggests that the top ice/debris glacial layer on the right has been sublimating away at this location, exposing the lower ice/debris glacial layer on the left.

On Earth, the breakup on the edge of a glacier takes place in sudden events, when large pieces of ice break off due to the freeze/thaw cycle caused by daily and seasonal temperature changes. Though the process is not fast, it does happen in quick bursts as each piece breaks away.

On Mars, the ice doesn’t break off and fall into water. Instead, the ice sublimates directly from a solid to a gas. As this often happens just below the surface (which is usually dirt and debris protecting the ice), the gas pressure can cause that surface to burst, creating the cracks and holes we see here. Once those lower levels of purer ice are exposed, the sublimation accelerates, and soon the ice is gone.

In this case, once complete that sublimation process exposed the top protective layer of dirt/debris covering a lower glacier layer, probably laid down during an earlier Martian cycle of glacial growth.

This process might also provide us an explanation for a previous cool image, where the floor of a crater in the southern cratered mid-latitudes appeared to be peeling away.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

 
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.


The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
 

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News

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