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.
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 are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also 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.
Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.
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.
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 are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also 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.
Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.
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.