The wavy and beautiful edge of the northern ice cap of Mars
Click for full image.
Cool image time! The photo to the right, cropped and reduced to post here, was taken on August 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the many layered scarp that forms the edge of the northern polar ice cap on Mars, probably more than 2,000 feet high.
Those layers are significant, as they indicate the many climate cycles that scientists think Mars has undergone over the eons as the red planet’s rotational tilt, or obliquity, rocked back and forth from 11 degrees inclination to as much as 60 degrees. At the extremes, the ice cap was either growing or shrinking, while today (at 25 degrees inclination) it appears to be in a steady state.
Why the layers alternate light and dark is not known. The shift from lighter colors at the top half and the dark bottom half marks the separation between the top water ice cap and what scientists label the basal unit. It also marks some major change in Mars’ climate and geology that occurred about 4.5 million years ago.
The yellow cross on the overview map to the right indicates the location of this scarp. Because the pole’s scarps near the bottom of this map, where this photo was taken, tend to be less steep, most of the seasonal avalanches that occur in the spring are found along the scarps near the top of the map.
The origin of the hollow, where the scarp is retreating faster, is also unknown. For some reason something caused more erosion at this point. If it was an avalanche in the far past, all evidence of that event is gone. That the basal unit shows no such erosion suggests the origin is much more complicated than an avalanche.
One not obvious detail about this part of Mars is its daily weather. Though this is springtime and the Sun is out, it is very cold here, far colder than the coldest places on Earth. Though temperatures can get above freezing in the equatorial regions, at the poles that almost never happens. The planet’s average temperature globally is -81 degrees Fahrenheit. This means that at this spot the temperature when this photo was taken was likely well below zero degrees Fahrenheit, probably by many tens of degrees.
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.
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Click for full image.
Cool image time! The photo to the right, cropped and reduced to post here, was taken on August 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the many layered scarp that forms the edge of the northern polar ice cap on Mars, probably more than 2,000 feet high.
Those layers are significant, as they indicate the many climate cycles that scientists think Mars has undergone over the eons as the red planet’s rotational tilt, or obliquity, rocked back and forth from 11 degrees inclination to as much as 60 degrees. At the extremes, the ice cap was either growing or shrinking, while today (at 25 degrees inclination) it appears to be in a steady state.
Why the layers alternate light and dark is not known. The shift from lighter colors at the top half and the dark bottom half marks the separation between the top water ice cap and what scientists label the basal unit. It also marks some major change in Mars’ climate and geology that occurred about 4.5 million years ago.
The yellow cross on the overview map to the right indicates the location of this scarp. Because the pole’s scarps near the bottom of this map, where this photo was taken, tend to be less steep, most of the seasonal avalanches that occur in the spring are found along the scarps near the top of the map.
The origin of the hollow, where the scarp is retreating faster, is also unknown. For some reason something caused more erosion at this point. If it was an avalanche in the far past, all evidence of that event is gone. That the basal unit shows no such erosion suggests the origin is much more complicated than an avalanche.
One not obvious detail about this part of Mars is its daily weather. Though this is springtime and the Sun is out, it is very cold here, far colder than the coldest places on Earth. Though temperatures can get above freezing in the equatorial regions, at the poles that almost never happens. The planet’s average temperature globally is -81 degrees Fahrenheit. This means that at this spot the temperature when this photo was taken was likely well below zero degrees Fahrenheit, probably by many tens of degrees.
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.
Is it my imagination, or is the ice cap generally spiral in structure especially near the pole? Aware of any speculation / hypothesis as to why that might be? Coriolis effect? (but I’ve never heard it applied to solid structures)
Greg the Geologist: I remember reading a paper somewhere discussing this. Your impression is correct. See this post on BtB:
https://behindtheblack.com/behind-the-black/points-of-information/mars-polar-ice-canyons-are-young-and-the-source-for-mid-latitude-ice/
Greg the Geologist: “Coriolis effect? (but I’ve never heard it applied to solid structures)”
The CO2 and water vapor from which the ices condense are gases, not a solid, and thus would respond to coriolis forces. The deposition of the condensates could mimic the flow patterns of the gases.
So Mars dose have Ice Cap proof of moister on Mars and where Marvin and K_9 go skinig