Seasonal avalanches in Martian dune gully
Click for full image.
The science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) today released a very cool pair of images, taken a Martian year apart, showing some significant changes that had occurred during that time in a large sand dune slope inside a crater. On the right is that pair, reduced and with the top image slightly lightened to bring out the features. As they wrote in the caption,
One large gully in particular has had major changes in every Martian winter since [MRO’s high resolution camera] began monitoring, triggered by the seasonal dry ice frost that accumulates each year.
This time there was an especially large change, depositing a huge mass of sand. The sand divided into many small toes near its end, or perhaps many individual flows descended near the same spot. Additionally, a long sinuous ridge of sand was deposited. This could be a “levee” that formed along one side of a flow, but there is not much sand past the end of the ridge, so it might also be the main body of a flow.
Nor is this dune gully the only active one in this crater, dubbed Matara Crater, located in the southern cratered highlands at about 50 degrees south latitude. If you look at the full image and compare it with an image from 2009 there are many changes across the entire slope field that extends a considerable distance to the north and south of the cropped section shown above.
At this latitude atmospheric carbon dioxide settles as frost during the winter, then sublimates away with the coming of spring. The freeze-sublimation process disturbs the sand each year, causing these avalanches.
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.
The science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) today released a very cool pair of images, taken a Martian year apart, showing some significant changes that had occurred during that time in a large sand dune slope inside a crater. On the right is that pair, reduced and with the top image slightly lightened to bring out the features. As they wrote in the caption,
One large gully in particular has had major changes in every Martian winter since [MRO’s high resolution camera] began monitoring, triggered by the seasonal dry ice frost that accumulates each year.
This time there was an especially large change, depositing a huge mass of sand. The sand divided into many small toes near its end, or perhaps many individual flows descended near the same spot. Additionally, a long sinuous ridge of sand was deposited. This could be a “levee” that formed along one side of a flow, but there is not much sand past the end of the ridge, so it might also be the main body of a flow.
Nor is this dune gully the only active one in this crater, dubbed Matara Crater, located in the southern cratered highlands at about 50 degrees south latitude. If you look at the full image and compare it with an image from 2009 there are many changes across the entire slope field that extends a considerable distance to the north and south of the cropped section shown above.
At this latitude atmospheric carbon dioxide settles as frost during the winter, then sublimates away with the coming of spring. The freeze-sublimation process disturbs the sand each year, causing these avalanches.
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
These posts do not get as many comments, but I do enjoy them immensely.
I feel I should comment so you know they are appreciated.
Also, came across this yesterday:
https://www.livescience.com/nasa-telescope-far-side-of-moon.html
As an amateur astronomer, I have advocated for a far side observatory myself, I think
this is great. I have not found a whole lot about this project just yet.
I also advocate for a standard spectrum scope on the far side as well.
sippin_bourbon: Thank you for the kind words. I do wonder at times if anyone is actually reading my science posts. It seems from the comments the only thing people these days really care about is politics. Though very very important, life should never be all politics. When it is, things are not good.
A radio telescope on the far side of the Moon makes great sense. This research however is very much in the powerpoint stage. We need to be able to get there, reliably, at low cost, before I will take it very seriously.
I do wonder at times if anyone is actually reading my science posts.
Definitely. But it’s often hard for me to ask or add something of substance when it comes to geological aspects.
Ian C: As I used to tell my film students when I was teaching film in New York back in the early 1990s, the only stupid question is the one you don’t ask. Feel free to speculate and ask! In truth, as I say repeatedly, your guess is often as good as mine. And mine are sometimes (rarely) as good as the planetary geologists who do this for a living.