A Martian gully formed by disappearing glacial ice?
Click for original image.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on April 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the rim of a seventeen-mile wide crater, and was the scientists label a “gully without apron,” meaning that though something has caused material to disappear within that gully, beginning high on the rim wall, there does not appear to be any piled up apron or debris at the gully’s base.
The blue colors imply the possibility of frost within the gully, while the orange suggests dust or coarse surface material.
The cracks emanating away at right angles from the gully’s base suggest glacial ice, which makes sense based on the location.
The white dot northeast of Lyot Crater marks this location on the overview map to the right. At 54 degrees north latitude, finding evidence of glacial ice within this crater would not be surprising, especially as it sits north of the 2,000-mile-long mid-latitude strip I dub glacier country, as almost every image suggests the presence of glaciers.
This location, combined with those cracks, suggests the gully is actually a place where that glacial ice has sublimated away, thus explaining the lack of a debris apron at its base.
Sounds good, eh? Well, the uncertainty of science remains. A paper just published in
Journal of Geophysical Research: Planets took a close look at the orbital radar data gathered by MRO’s SHARAD instrument and found that there could be less ice here near the surface than the features suggest. SHARAD’s radar specifically looks at the immediate surface layers, what the paper calls the “mantle”. From the abstract:
We find that mantle layers have radar characteristics more consistent with a low ice content and properties that greatly reduce the strength of the radar signal. Further, we find radar evidence consistent with mantle layers burying the ends of glacial ice. This study demonstrates that mantle layers on Mars have a wide range of ice contents and ages, with some being less ice rich than their surface characteristics alone might imply.
This result does not mean there is no glacier here, but that the debris on top that protects it has less ice in it than previously thought. In a sense this makes the existence of underground ice in these mid- and high- latitude regions more likely, as the mantle of dust and debris that protects it is more structurally sound.
In this particular case, however, circumstances likely caused that surface mantle to erode away enough that the ice below was exposed to sunlight and sublimated away. Some underground drainage down the rim slope might have also contributed.
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:
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4. Donate by check, payable to Robert Zimmerman and mailed to
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Click for original image.
Cool image time! The picture to the right, cropped and reduced to post here, was taken on April 30, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the rim of a seventeen-mile wide crater, and was the scientists label a “gully without apron,” meaning that though something has caused material to disappear within that gully, beginning high on the rim wall, there does not appear to be any piled up apron or debris at the gully’s base.
The blue colors imply the possibility of frost within the gully, while the orange suggests dust or coarse surface material.
The cracks emanating away at right angles from the gully’s base suggest glacial ice, which makes sense based on the location.
The white dot northeast of Lyot Crater marks this location on the overview map to the right. At 54 degrees north latitude, finding evidence of glacial ice within this crater would not be surprising, especially as it sits north of the 2,000-mile-long mid-latitude strip I dub glacier country, as almost every image suggests the presence of glaciers.
This location, combined with those cracks, suggests the gully is actually a place where that glacial ice has sublimated away, thus explaining the lack of a debris apron at its base.
Sounds good, eh? Well, the uncertainty of science remains. A paper just published in
Journal of Geophysical Research: Planets took a close look at the orbital radar data gathered by MRO’s SHARAD instrument and found that there could be less ice here near the surface than the features suggest. SHARAD’s radar specifically looks at the immediate surface layers, what the paper calls the “mantle”. From the abstract:
We find that mantle layers have radar characteristics more consistent with a low ice content and properties that greatly reduce the strength of the radar signal. Further, we find radar evidence consistent with mantle layers burying the ends of glacial ice. This study demonstrates that mantle layers on Mars have a wide range of ice contents and ages, with some being less ice rich than their surface characteristics alone might imply.
This result does not mean there is no glacier here, but that the debris on top that protects it has less ice in it than previously thought. In a sense this makes the existence of underground ice in these mid- and high- latitude regions more likely, as the mantle of dust and debris that protects it is more structurally sound.
In this particular case, however, circumstances likely caused that surface mantle to erode away enough that the ice below was exposed to sunlight and sublimated away. Some underground drainage down the rim slope might have also contributed.
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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