A Martian crater, ice, and dust devil tracks
Click for original image.
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 2, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is once again a terrain sample image, taken not for any specific research but to fill a gap in the schedule so as to maintain the camera’s proper temperature.
What this picture shows is that even though Mars has a thin atmosphere that produces dust devils, the propagation of dust devils is not uniform across the red planet’s surface. In this picture there are a lot of devil tracks, going in many different directions. Yet few of the many cool images I post from MRO show this number of tracks. In many cases the ground might not be agreeable to leaving tracks, but that cannot be the entire explanation.
The location of this crater, indicated by the red dot on the global map of Mars to the right, is in the high southern latitudes, at 63 degrees south. It is also located about 600 miles south of the southern edge of Hellas Basin, in a region where ice scarps are found and it is thought that there is a lot of near surface ice below the ground.
Thus, this terrain is likely quite icy. We might even be looking at a glacial ice sheet, covering the entire surface with only a thin layer of dust on top to protect it. The crater itself appears to be partly buried in such a thing. Yet, though I have posted many many MRO photos of similar ice terrain in the high latitudes, few have this many dust devil tracks. Most have none.
There is already evidence in the dry equatorial regions of dark splotches that appear to attract dust devils, for reasons that remain unclear. The most popular explanation is that the dark surface is warmer, and the devils are attracted to that warmth. They in turn scour the surface of dust, making it darker, and therefore reinforce the process.
This theory however doesn’t work at today’s location, in the high icy latitudes. The ground isn’t dark, and the devils don’t seem attracted to any particular area.
It is all a mystery, compelling and baffling, but enormously fun to contemplate.
Readers!
Every February I run a fund-raising drive during my birthday month. This year I celebrate my 72nd birthday, and hope and plan to continue writing and posting on Behind the Black for as long as I am able.
I hope my readers will support this effort. As I did in my November fund-raising drive, I am offering autographed copies of my books for large donations. Donate $250 and you can have a choice of the hardback of either Genesis: the Story of Apollo 8 or Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space. Donate $200 and you can get an autographed paperback copy of either.
Please consider supporting my work here at Behind the Black. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID 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. Every one of those 2020 conclusions has turned out right.
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.
Click for original image.
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on January 2, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is once again a terrain sample image, taken not for any specific research but to fill a gap in the schedule so as to maintain the camera’s proper temperature.
What this picture shows is that even though Mars has a thin atmosphere that produces dust devils, the propagation of dust devils is not uniform across the red planet’s surface. In this picture there are a lot of devil tracks, going in many different directions. Yet few of the many cool images I post from MRO show this number of tracks. In many cases the ground might not be agreeable to leaving tracks, but that cannot be the entire explanation.
The location of this crater, indicated by the red dot on the global map of Mars to the right, is in the high southern latitudes, at 63 degrees south. It is also located about 600 miles south of the southern edge of Hellas Basin, in a region where ice scarps are found and it is thought that there is a lot of near surface ice below the ground.
Thus, this terrain is likely quite icy. We might even be looking at a glacial ice sheet, covering the entire surface with only a thin layer of dust on top to protect it. The crater itself appears to be partly buried in such a thing. Yet, though I have posted many many MRO photos of similar ice terrain in the high latitudes, few have this many dust devil tracks. Most have none.
There is already evidence in the dry equatorial regions of dark splotches that appear to attract dust devils, for reasons that remain unclear. The most popular explanation is that the dark surface is warmer, and the devils are attracted to that warmth. They in turn scour the surface of dust, making it darker, and therefore reinforce the process.
This theory however doesn’t work at today’s location, in the high icy latitudes. The ground isn’t dark, and the devils don’t seem attracted to any particular area.
It is all a mystery, compelling and baffling, but enormously fun to contemplate.
Readers!
Every February I run a fund-raising drive during my birthday month. This year I celebrate my 72nd birthday, and hope and plan to continue writing and posting on Behind the Black for as long as I am able.
I hope my readers will support this effort. As I did in my November fund-raising drive, I am offering autographed copies of my books for large donations. Donate $250 and you can have a choice of the hardback of either Genesis: the Story of Apollo 8 or Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space. Donate $200 and you can get an autographed paperback copy of either.
Please consider supporting my work here at Behind the Black. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID 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. Every one of those 2020 conclusions has turned out right.
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.
It is good to remember that at least on Earth the atmospheric convection to power dust devils (and tornadoes) is not the absolute warmth of the ground, but the difference in temperature between the ground layer of air and higher altitude air.
Cooler air over warmer air allows bubbles of warm air to pop up from the ground like virtual hot-air balloons, while the Coriolis effects cause the inflowing airflow to curve and spin. Of course the radically different Martian atmosphere chemistry, density, temperatures, and much lower gravity would all make a quantitative difference from the dust devils of Earth, but the basic physics is probably the same.
Surface features like hills, scarps, and volcanoes probably do the job of triggering vertical displacements from winds just as on Earth.
From a track near the center of the crater it appears that one dust devil split in two. Is that known to happen? What about with Earthly tornadoes?
Michael McNeil: I don’t know if a dust devil can split. I doubt it. What you see here is simply different tracks of different devils that happened to cross in just this manner.