Monitoring the tiger stripes on Martian dunes
Click for full image.
Today’s cool image takes us back to a previous cool image, from December 2020. The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on August 22, 2022 as part of a regular monitoring program of these worm-shaped and tiger-striped dunes in 42-mile-wide Kunowsky Crater, located in the northern lowland plains of Mars at the high mid-latitude of 57 degrees north.
The tiger stripes appear to be the northern hemisphere’s version of what are called “spiders” in the south, where each spring the mantle of dry ice that settles on the surface in winter begins to sublimate away, from the bottom up. The trapped gas eventually escapes at the mantle’s weak points where it cracks.
When the gas escapes it spews dust onto the surface, creating the dark patches. In the southern hemisphere, the ground is generally stable, and the gas travels and escapes along the same routes each year, creating relatively permanent spider-like tributary patterns. In the north the ground is less stable, so the dark streaks form more randomly from year to year.
This monitoring campaign, first begun in 2008, is looking to see how these seasonal changes might change these northern dunes. The white rectangle in the image shows an area shown in close-up below, comparing 2020 with 2022 to see what changes might have occurred.
For original images, go here and here.
If you look close, you will see that the dark stripes are not in the exact same places, though there are large similarities. From spring to spring the carbon dioxide gas breaks through the dry ice mantle in approximately the same places, but those places do shift somewhat from year to year. These changes suggest that while the dunes appear largely stable, the sublimation of the gas is causing some surface changes yearly.
One more detail. The bluish tint to the flat plain surrounding these dunes suggests that the dunes almost certainly sit on a sheet of water ice, protected by a layer of dust. At 57 degrees north latitude, it is thought that there is a lot of near surface ice on Mars, much of it formed as sheets of dust, dirt, and ice mixed together. The blue color of the flat plains here reinforces this hypothesis.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for full image.
Today’s cool image takes us back to a previous cool image, from December 2020. The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on August 22, 2022 as part of a regular monitoring program of these worm-shaped and tiger-striped dunes in 42-mile-wide Kunowsky Crater, located in the northern lowland plains of Mars at the high mid-latitude of 57 degrees north.
The tiger stripes appear to be the northern hemisphere’s version of what are called “spiders” in the south, where each spring the mantle of dry ice that settles on the surface in winter begins to sublimate away, from the bottom up. The trapped gas eventually escapes at the mantle’s weak points where it cracks.
When the gas escapes it spews dust onto the surface, creating the dark patches. In the southern hemisphere, the ground is generally stable, and the gas travels and escapes along the same routes each year, creating relatively permanent spider-like tributary patterns. In the north the ground is less stable, so the dark streaks form more randomly from year to year.
This monitoring campaign, first begun in 2008, is looking to see how these seasonal changes might change these northern dunes. The white rectangle in the image shows an area shown in close-up below, comparing 2020 with 2022 to see what changes might have occurred.
For original images, go here and here.
If you look close, you will see that the dark stripes are not in the exact same places, though there are large similarities. From spring to spring the carbon dioxide gas breaks through the dry ice mantle in approximately the same places, but those places do shift somewhat from year to year. These changes suggest that while the dunes appear largely stable, the sublimation of the gas is causing some surface changes yearly.
One more detail. The bluish tint to the flat plain surrounding these dunes suggests that the dunes almost certainly sit on a sheet of water ice, protected by a layer of dust. At 57 degrees north latitude, it is thought that there is a lot of near surface ice on Mars, much of it formed as sheets of dust, dirt, and ice mixed together. The blue color of the flat plains here reinforces this hypothesis.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
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