Land of knobs
Click for original image.
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 17, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “terrain sample,” it was likely taken not as part of any specific research project, but to fill a gap in the camera’s schedule in order to maintain its proper temperature.
When the camera team does this, they try to pick interesting targets. In this case, they targeted this 400-foot-high pointy-topped hill. The smoothness of its slopes suggest this hill is made up largely of packed dust, possibly a hardened former dune. This hypothesis seems strengthened by the erosion on the eastern slopes, which appears to be areas where that packed sand has worn or blow away.
Think of sandstone in the American southwest. It is made of sand that has hardened into rock, but wind and water and friction can easily break it back into dust particles, resulting often in the spectacular and weird geological shapes that make the southwest so enticing.
But is this sand?
The white dot on the overview map to the right marks this location, about 330 miles south of the peak of Olympus Mons. The inset shows that this pointy hill is not unique, and is actually just one of hundreds across an east-west strip, dubbed Gigas Sulci, about 380 miles long and 50 to 80 miles wide.
This is truly a land of knobs. If these hills are formed of packed sand, it is likely packed volcanic ash, deposited by the many giant volcanoes that surround it when they were active more than a billion years ago. Since then the ash got compacted and then began eroding away to leave behind the knobs.
It is also quite possible that this is instead hard lava that has eroded away. A third possibility is a combination of volcanic ash and hard lava. The lava could be the knobs, deposited during an eruption and then covered deeply by later volcanic ash. The ash hardened, then eroded away, revealing the more resistant lava hills.
All guesses. But then, it is always fun to guess, as long as you always remind yourself that you are guessing, and need to know more to guess more accurately.
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, rotated, cropped, reduced, and sharpened to post here, was taken on July 17, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “terrain sample,” it was likely taken not as part of any specific research project, but to fill a gap in the camera’s schedule in order to maintain its proper temperature.
When the camera team does this, they try to pick interesting targets. In this case, they targeted this 400-foot-high pointy-topped hill. The smoothness of its slopes suggest this hill is made up largely of packed dust, possibly a hardened former dune. This hypothesis seems strengthened by the erosion on the eastern slopes, which appears to be areas where that packed sand has worn or blow away.
Think of sandstone in the American southwest. It is made of sand that has hardened into rock, but wind and water and friction can easily break it back into dust particles, resulting often in the spectacular and weird geological shapes that make the southwest so enticing.
But is this sand?
The white dot on the overview map to the right marks this location, about 330 miles south of the peak of Olympus Mons. The inset shows that this pointy hill is not unique, and is actually just one of hundreds across an east-west strip, dubbed Gigas Sulci, about 380 miles long and 50 to 80 miles wide.
This is truly a land of knobs. If these hills are formed of packed sand, it is likely packed volcanic ash, deposited by the many giant volcanoes that surround it when they were active more than a billion years ago. Since then the ash got compacted and then began eroding away to leave behind the knobs.
It is also quite possible that this is instead hard lava that has eroded away. A third possibility is a combination of volcanic ash and hard lava. The lava could be the knobs, deposited during an eruption and then covered deeply by later volcanic ash. The ash hardened, then eroded away, revealing the more resistant lava hills.
All guesses. But then, it is always fun to guess, as long as you always remind yourself that you are guessing, and need to know more to guess more accurately.
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
I do not have a better expectation.
Although there is one slope streak in the bottom left that appears to cross over gullies before puddling. Very usual substance behaving oddly… Super critical fluid?
I”ve been following too many UK sites. First thing I thought of was the British meaning of “knob” :)