A plateau of friable rock on Mars
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The science team labels this “Friable Outcrops in Aeolis Dorsa.” What we are looking at is the northeasternmost tip of a 30-mile long plateau that marks the northern edge of Mars southern cratered highlands. For most of its length the top of that plateau is relatively smooth, broken by some vague surface features and a few scattered craters (suggesting it is relatively young). However, as you approach the plateau’s edges and especially that northeastern tip the surface begins to break up into the rough terrain shown to the right. It appears that the prevailing winds from the north are scouring the soft topsoil here and causing it to wear away, leaving behind those innumerable small ridges, almost all of which are oriented from north-to-south.
But why is the topsoil here soft and so easily scoured?
The white dot on the overview map to the right marks the location, with the inset providing a wider view of this entire plateau. The location is at the edge of the Medusae Fossae Formation, the largest volcanic ash deposit on Mars. The young surface of this plateau is likely a layer of that ash, which even if it has hardened over the eons into solid rock will still be easily eroded, much like sandstone on Earth. Visually it appears that the plateau is wearing away along its edges, the places that are hit first by the prevailing winds.
It is not confirmed however that the plateau is made of volcanic ash. It is also possible that it was a deposit of flood lava that poured out to the northeast after the impact of a 30-mile-wide crater about 37 miles to the southwest. Depending on the composition of the lava, which in Mars’ one third gravity could be far less dense that lava found on Earth, it could as friable as hardened ash, producing the same features.
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
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on September 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The science team labels this “Friable Outcrops in Aeolis Dorsa.” What we are looking at is the northeasternmost tip of a 30-mile long plateau that marks the northern edge of Mars southern cratered highlands. For most of its length the top of that plateau is relatively smooth, broken by some vague surface features and a few scattered craters (suggesting it is relatively young). However, as you approach the plateau’s edges and especially that northeastern tip the surface begins to break up into the rough terrain shown to the right. It appears that the prevailing winds from the north are scouring the soft topsoil here and causing it to wear away, leaving behind those innumerable small ridges, almost all of which are oriented from north-to-south.
But why is the topsoil here soft and so easily scoured?
The white dot on the overview map to the right marks the location, with the inset providing a wider view of this entire plateau. The location is at the edge of the Medusae Fossae Formation, the largest volcanic ash deposit on Mars. The young surface of this plateau is likely a layer of that ash, which even if it has hardened over the eons into solid rock will still be easily eroded, much like sandstone on Earth. Visually it appears that the plateau is wearing away along its edges, the places that are hit first by the prevailing winds.
It is not confirmed however that the plateau is made of volcanic ash. It is also possible that it was a deposit of flood lava that poured out to the northeast after the impact of a 30-mile-wide crater about 37 miles to the southwest. Depending on the composition of the lava, which in Mars’ one third gravity could be far less dense that lava found on Earth, it could as friable as hardened ash, producing the same features.
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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