Craters in a row
Click for original image.
Cool image time from Mars! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It highlights a string of craters, all lined up in an almost straight line.
Were these craters caused by the impact of an asteroid that broke up as it burned its way through the thin Martian atmosphere? The lack of any raised rims argues instead that these are sinks produced not from impact but from a collapse into a void below, possibly a fault line.
Yet, almost all of the craters in this image, even those not part of this crater string, show no raised rims. If sinks, the voids below don’t seem to follow any pattern, which once again argues in favor of random impacts, with the string produced by a bolide breaking up just prior to hitting the ground.
The white dot on the overview map to the right marks this location. The rectangle in the inset shows in the area covered by the picture above.
The overview map also gives some additional hints about the origin of this crater string. It is located on the relatively flat plateau that begins the southern cratered highlands to the south, indicated by yellow to note its higher elevation. Across that entire plateau are many random craters like this string, almost all lacking raised rims.
The inset also shows a large unnamed 25-mile-wide crater about 17 miles to the northwest. This large crater has a raised rim as well as central peaks, strongly suggesting it was caused by an impact. Furthermore, the context map on the picture’s webpage shows similar large craters surrounding this plateau. Thus, the plateau’s scattered small craters, including this string, could have formed as secondary impacts from the ejected material from the surrounding large impacts.
But why do these small craters lack raised rims? The answer to this mystery probably lies with the latitude, 40 degrees north. This is glacier country. On the southern cratered highlands here it is very possible that the ground is heavily impregnated with ice. The secondary impacts would have hit this ground while still hot, so rather than create a normal crater the material simply melted that ice and sank downward. Think of what happens when you drop boiling water on ice.
I am guessing however. We would need to know more about the chemistry of this ground, which might contain ice but then might not.
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 from Mars! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 13, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It highlights a string of craters, all lined up in an almost straight line.
Were these craters caused by the impact of an asteroid that broke up as it burned its way through the thin Martian atmosphere? The lack of any raised rims argues instead that these are sinks produced not from impact but from a collapse into a void below, possibly a fault line.
Yet, almost all of the craters in this image, even those not part of this crater string, show no raised rims. If sinks, the voids below don’t seem to follow any pattern, which once again argues in favor of random impacts, with the string produced by a bolide breaking up just prior to hitting the ground.
The white dot on the overview map to the right marks this location. The rectangle in the inset shows in the area covered by the picture above.
The overview map also gives some additional hints about the origin of this crater string. It is located on the relatively flat plateau that begins the southern cratered highlands to the south, indicated by yellow to note its higher elevation. Across that entire plateau are many random craters like this string, almost all lacking raised rims.
The inset also shows a large unnamed 25-mile-wide crater about 17 miles to the northwest. This large crater has a raised rim as well as central peaks, strongly suggesting it was caused by an impact. Furthermore, the context map on the picture’s webpage shows similar large craters surrounding this plateau. Thus, the plateau’s scattered small craters, including this string, could have formed as secondary impacts from the ejected material from the surrounding large impacts.
But why do these small craters lack raised rims? The answer to this mystery probably lies with the latitude, 40 degrees north. This is glacier country. On the southern cratered highlands here it is very possible that the ground is heavily impregnated with ice. The secondary impacts would have hit this ground while still hot, so rather than create a normal crater the material simply melted that ice and sank downward. Think of what happens when you drop boiling water on ice.
I am guessing however. We would need to know more about the chemistry of this ground, which might contain ice but then might not.
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
We saw that with Shoemaker-Levy 9.
Jupiter breaks one up…then machine guns Mars instead by slingshoting them back.
An example of how evenly spaced linear alignment of multiple bodies on the same trajectory can be brief.
https://www.youtube.com/watch?v=41Kq36GouaE
I’m going with impact. Interesting how the craters form a rough mirror image around a medial line, and the impact is weighted to one side. Probably make some reasonable assumptions about the impactor composition from that.