Dunes on the floor of Valles Marineris
Click for original image.
Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 26, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a field of scattered elongated dunes on a flat older surface with craters and what appear to be smaller ripple dunes (in the lower left). The large elongated dunes tend to be oriented in an east-west manner, while the older tiny ripple dunes appear to have a north-south orientation.
Very clearly the larger dunes appear to be traveling across that flat older surface, though whether there is any documented movement is unknown. Generally (though there are exceptions) scientists have found most of the dunes on Mars to be either inactive, or if they are moving because of the wind that movement is very tiny per year. In this case there is one dark spot on the dunes, near the center of the picture, where it appears a collapse might have occurred, suggesting recent change.
On the center right of the picture is the end point of a long ridgeline extending 10 to 12 miles to the east and rising about 7,300 feet, as shown in the overview map above. The small rectangle in the inset shows the area covered by the photograph.
At the base of that ridgeline can be seen a series of terraces descending to the west, suggesting that this hill might be volcanic in nature, with each terrace indicating a separate lava flow. The location is in the dry equatorial regions, so near-surface ice is likely not an explanation.
In the inset the mountain wall to the north is the large mountain chain that bisects this part of Valles Marineris. It overwhelms this small 7,300-foot-high ridge, rising more than 22,000 feet from these dunes with its high point still one or two thousand feet below the rim of Valles Marineris itself.
Once again, the grand scenery of Mars amazes. Imaging hiking a trail along that ridgeline, with the mountains rising far above you to the north and south.
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 print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
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 original image.
Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 26, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a field of scattered elongated dunes on a flat older surface with craters and what appear to be smaller ripple dunes (in the lower left). The large elongated dunes tend to be oriented in an east-west manner, while the older tiny ripple dunes appear to have a north-south orientation.
Very clearly the larger dunes appear to be traveling across that flat older surface, though whether there is any documented movement is unknown. Generally (though there are exceptions) scientists have found most of the dunes on Mars to be either inactive, or if they are moving because of the wind that movement is very tiny per year. In this case there is one dark spot on the dunes, near the center of the picture, where it appears a collapse might have occurred, suggesting recent change.
On the center right of the picture is the end point of a long ridgeline extending 10 to 12 miles to the east and rising about 7,300 feet, as shown in the overview map above. The small rectangle in the inset shows the area covered by the photograph.
At the base of that ridgeline can be seen a series of terraces descending to the west, suggesting that this hill might be volcanic in nature, with each terrace indicating a separate lava flow. The location is in the dry equatorial regions, so near-surface ice is likely not an explanation.
In the inset the mountain wall to the north is the large mountain chain that bisects this part of Valles Marineris. It overwhelms this small 7,300-foot-high ridge, rising more than 22,000 feet from these dunes with its high point still one or two thousand feet below the rim of Valles Marineris itself.
Once again, the grand scenery of Mars amazes. Imaging hiking a trail along that ridgeline, with the mountains rising far above you to the north and south.
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 print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. 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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