A frozen Martian splash
Click for original image.
Cool image time! The picture to the right, rotated, cropped, and enhanced to post here, was taken on July 11, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the southeast quadrant of a three-mile-wide unnamed crater that is surrounded on all sides by a dramatic but frozen splash apron of material, created when this impact occurred.
The rim rises between 200 to 400 feet from the surrounding plains, while the crater floor drops 700 feet to sit below those plains by 300 to 500 feet. In other words, that splash apron contains the material that was thrown up when the bolide drilled into the plain at impact, leaving behind this deep hole.
Why such a dramatic splash apron? Its existence suggests that the ground here was muddy, with a lot of water ice likely present. The location and wider context helps confirm this guess.
The white dot on the overview map marks the location, deep inside the giant Utopia Basin in the northern lowland plains of Mars. The small rectangle in the inset indicates the area covered by the picture above. Note the other craters in that inset. All have similar splash aprons.
Essentially, the ground here in Utopia Basin, at 33 degrees north latitude, is likely impregnated with near surface ice. When these impacts occurred that ice melted, producting a mud that — instead of being blasted away like rocks — splashed outward but quickly froze into these aprons. The presence of ripple dunes inside the hollows of that mud suggests this splash apron has likely been frozen for a very long time, allowing dust and volcanic ash to get trapped there and then slowly get shapped into these dunes by the thin Martian atmosphere.
It is possible these impacts all occurred at the same time, either as a collection of bolides arriving from space at the same time, or as secondary ejecta impacts from a much larger impact elsewhere. As there are several larger craters to the north, the latter is a possibility, but hardly confirmed.
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 or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. 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, and enhanced to post here, was taken on July 11, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the southeast quadrant of a three-mile-wide unnamed crater that is surrounded on all sides by a dramatic but frozen splash apron of material, created when this impact occurred.
The rim rises between 200 to 400 feet from the surrounding plains, while the crater floor drops 700 feet to sit below those plains by 300 to 500 feet. In other words, that splash apron contains the material that was thrown up when the bolide drilled into the plain at impact, leaving behind this deep hole.
Why such a dramatic splash apron? Its existence suggests that the ground here was muddy, with a lot of water ice likely present. The location and wider context helps confirm this guess.
The white dot on the overview map marks the location, deep inside the giant Utopia Basin in the northern lowland plains of Mars. The small rectangle in the inset indicates the area covered by the picture above. Note the other craters in that inset. All have similar splash aprons.
Essentially, the ground here in Utopia Basin, at 33 degrees north latitude, is likely impregnated with near surface ice. When these impacts occurred that ice melted, producting a mud that — instead of being blasted away like rocks — splashed outward but quickly froze into these aprons. The presence of ripple dunes inside the hollows of that mud suggests this splash apron has likely been frozen for a very long time, allowing dust and volcanic ash to get trapped there and then slowly get shapped into these dunes by the thin Martian atmosphere.
It is possible these impacts all occurred at the same time, either as a collection of bolides arriving from space at the same time, or as secondary ejecta impacts from a much larger impact elsewhere. As there are several larger craters to the north, the latter is a possibility, but hardly confirmed.
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 or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. 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