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Cracking glaciers on Mars

Cracking glaciers on Mars
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was released today as the picture of the day for the high resolution camera on Mars Reconnaissance Orbiter (MRO). Located in the 2,000 long northern mid-latitude strip that I dub Mars’ glacier country, it shows many of the numerous glacial features that are routinely found in images taken in this region. According to Dan Berman, senior scientist at the Planetary Science Institute in Arizona, who wrote the caption,

This observation shows a lobe-shaped debris apron emanating from a massif (shown in the upper left of the image) in the Protonilus Mensae region in the Northern Hemisphere of Mars. These aprons are composed of nearly pure water ice with a layer of debris on the surface protecting the ice from sublimation (going directly from a solid to gaseous state). This image shows different terrain types on the apron that indicate the presence and flow of ice, from smoother polygonal terrain closer to the massif, to rougher, patterned ground commonly called “brain terrain.” Also visible on the apron are a series of linear pits.

Protonilus Mensae is the central mensae region in that mid-latitude strip of glaciers.The overview map below shows the location of this photo in that region. Also below is a close-up of the linear pits and cracked terrain surrounding that oblong mound, as indicated by the white rectangle.

Overview map

cracking polygons and linear pits
Click for full image.

The white cross marks the location of the photo above. If you do a search on Behind the Black for “glaciers” or “glacier country,” you will find numerous images in this region, all showing similar glacial terrain. The latitude of the region ranges from 30 to 47 degrees, with this particular spot at 44 degrees. At that latitude almost every low spot will show glacial features, as noted by Berman above.

The close-up of the area in the rectangle is also to the right. The many polygonal cracks and linear pits surrounding this mound suggest that the buried glaciers at this location are sublimating away. Think of the polygonal cracks that appear in drying mud. A similar phenomenon is occurring here. At the ice sublimates into gas, the remaining solid ice cracks and shrinks, producing cracks and voids. In some cases the voids become large enough that they form the linear pits that surround this mound.

This pits are also comparable to the rifts and cracks that mountain climbers must deal with when they need to traverse Earth glaciers. The difference is that on Earth those glaciers are very active, with the ice moving and new cracks forming regularly.

On Mars these glaciers are thought to be no longer growing or moving. If any change is occurring it is sublimation and shrinking, though it remains unclear whether the glaciers in Mars’ mid-latitudes are in an overall steady state, or are growing or shrinking.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!


From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.


“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.


All editions available at Amazon, Barnes & Noble, and all book vendors. The ebook can be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner. Note that the price for the ebook, $3.99, goes up to $5.99 on September 1, 2022.


Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95). Just email me at zimmerman @ nasw dot org.

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