Polygons and scallops in the high mid-latitudes of the Martian lowland plains
Click for original image.
Cool image time! Only yesterday I posted an image of polygons in the dry equatorial regions of Mars, where little evidence of near-surface ice is found and are thought to be the remnants from a long-dried lakebed.
Today we take a look at some polygons in the mid-latitudes of the icy northern lowland plains, where near-surface ice appears ubiquitous and as it sublimates away with the changing seasons causes all kinds of strange formations, including polygons.
The picture to the right, cropped, reduced, and sharpened to post here, is a good example, centered on a 0.6-mile-wide bright crater that appears to be filled with glacial ice. The image was taken on June 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and is located at 44 degrees north latitude on the western edge of Utopia Basin. As noted by the MRO science team in 2006 for a different MRO picture with similar features:
The scalloped depressions are typical features; a smooth layered terrain located between 40 and 60 degrees in both hemispheres. Scalloped depressions probably form by removal of ice-rich subsurface material by sublimation (ice transforming directly from a solid to a gaseous state), a process that may still be active today. Isolated scalloped depressions generally have a steep pole-facing scarp and a gentler equator-facing slope. This asymmetry is interpreted as being the result of difference in solar heating. Scalloped depressions may coalesce, leading to the formation of large areas of pitted terrain.
The polygonal pattern of fractures resembles permafrost polygons that form in terrestrial polar and high alpine regions by seasonal-to-annual contraction of the permafrost (permanently frozen ground). On Earth, such polygons indicate the presence of ground ice.
On the overview map to the right the white dot marks the location. The inset illustrates the icy nature of the surface at these latitudes in the northern plains, with several much larger craters nearby (the largest about 35 miles across) surrounded by frozen splash aprons.
Readers!
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In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
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Click for original image.
Cool image time! Only yesterday I posted an image of polygons in the dry equatorial regions of Mars, where little evidence of near-surface ice is found and are thought to be the remnants from a long-dried lakebed.
Today we take a look at some polygons in the mid-latitudes of the icy northern lowland plains, where near-surface ice appears ubiquitous and as it sublimates away with the changing seasons causes all kinds of strange formations, including polygons.
The picture to the right, cropped, reduced, and sharpened to post here, is a good example, centered on a 0.6-mile-wide bright crater that appears to be filled with glacial ice. The image was taken on June 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO), and is located at 44 degrees north latitude on the western edge of Utopia Basin. As noted by the MRO science team in 2006 for a different MRO picture with similar features:
The scalloped depressions are typical features; a smooth layered terrain located between 40 and 60 degrees in both hemispheres. Scalloped depressions probably form by removal of ice-rich subsurface material by sublimation (ice transforming directly from a solid to a gaseous state), a process that may still be active today. Isolated scalloped depressions generally have a steep pole-facing scarp and a gentler equator-facing slope. This asymmetry is interpreted as being the result of difference in solar heating. Scalloped depressions may coalesce, leading to the formation of large areas of pitted terrain.
The polygonal pattern of fractures resembles permafrost polygons that form in terrestrial polar and high alpine regions by seasonal-to-annual contraction of the permafrost (permanently frozen ground). On Earth, such polygons indicate the presence of ground ice.
On the overview map to the right the white dot marks the location. The inset illustrates the icy nature of the surface at these latitudes in the northern plains, with several much larger craters nearby (the largest about 35 miles across) surrounded by frozen splash aprons.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
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