A river on Mars
Cool image time! The science team for the high resolution camera on Mars Reconnaissance Orbiter this week released it monthly set of cool images. One of those images, which I have cropped and reduced to show it here, is of an ancient river on Mars, the formation process of which geologists still debate. As the scientists note,
The channel pattern, called “dendritic” because of its tree–like branching, begins at the top of the image and runs down over the rim of an ancient impact basin across the basin floor. The soil surface overlying these channels, and indeed the entire landscape, has been changed and reworked over the intervening millions of years, by the combined actions of wind and ice. Over time, the original channels become muted or even erased.
One thing I learned in writing an article for Astronomy about the rivers seen on Saturn’s moon Titan is that without plant life there is no known natural process to hold river banks in place. Instead, if the grade is shallow and not confined by bedrock cliffs, rivers will meander about randomly forming braided channels as there will be nothing on shore to hold the water within the same course. For example, on a lifeless Earth the water draining the central basin of the midwest United States would have flowed south across a wide scattered area covering the entire plains, rather than flowing within the courses of the Missouri and Mississippi rivers.
Thus, it is not surprising that this river on Mars appears muted or partly erased. It probably was never very clearly delineated in the first place.
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 science team for the high resolution camera on Mars Reconnaissance Orbiter this week released it monthly set of cool images. One of those images, which I have cropped and reduced to show it here, is of an ancient river on Mars, the formation process of which geologists still debate. As the scientists note,
The channel pattern, called “dendritic” because of its tree–like branching, begins at the top of the image and runs down over the rim of an ancient impact basin across the basin floor. The soil surface overlying these channels, and indeed the entire landscape, has been changed and reworked over the intervening millions of years, by the combined actions of wind and ice. Over time, the original channels become muted or even erased.
One thing I learned in writing an article for Astronomy about the rivers seen on Saturn’s moon Titan is that without plant life there is no known natural process to hold river banks in place. Instead, if the grade is shallow and not confined by bedrock cliffs, rivers will meander about randomly forming braided channels as there will be nothing on shore to hold the water within the same course. For example, on a lifeless Earth the water draining the central basin of the midwest United States would have flowed south across a wide scattered area covering the entire plains, rather than flowing within the courses of the Missouri and Mississippi rivers.
Thus, it is not surprising that this river on Mars appears muted or partly erased. It probably was never very clearly delineated in the first place.
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
Interesting and you can see impact craters on top of the river bed, which should make dating easier.