Frozen Martian eddies at the confluence of two glacier rivers
Click for original image.
Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 3, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The science team labels the photo as capturing a “contact near Reull Vallis,” a 1,000-mile-long Martian canyon that flows down the eastern slopes of Hellas Basin, the death valley of Mars.
What I see isn’t a geological contact but a complex jumble of odd-shaped depressions and mesas, surrounded by an eroded surface that seems squashed and deformed by some process. If this is all we had to go on, I would simply label this as another “What the heck?” image on Mars and move on. However, the larger context of the overview map helps explain it all, at least as best as we can explain using orbital data.
The white dot on the overview map to the right marks the location, located in the upper half of Reull Vallis and focused on a short but wide tributary that flows northward into the main east-to-west channel. The arrows show the glacial flow direction, and in the inset those arrows I think provide an explanation for the jumbled features in the picture above.
Reull Vallis is essentially a glacial river, flowing roughly downhill from the east to the west into Hellas Basin. At this location the channel widens on the south so that an eddy can form at the outlet point of this side tributary (as indicated by the arrows). That eddy however impinges on the southeast-to-northwest flow of the tributory. The result is that the tributory’s flow is disturbed, resulting in the jumble we see in the picture above.
None of these glaciers are likely active at this time, however, as can be seen by dark slope streaks flowing down the main channel’s north interior cliffs. If the glacier was flowing those streaks would likely be distorted. Instead, they go straight downhill.
This eddy however illustrates why glaciers might possibly explain the many riverlike channels on Mars, rather than flowing liquid water. Though glaciers work very slowly, on Mars they have endless time to do so, as the temperature is almost never above freezing. And since there appears to be plenty of surface or near-surface ice on the planet, especially above 30 degrees latitude, that ice has had the opportunity to do a lot of carving.
The eddy shows the glacier can act just like a river, though much slower. Given enough time and enough ice, there really is no reason that glacial ice can’t carve out channels similar to the channels that rivers carve.
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, reduced, and sharpened to post here, was taken on July 3, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The science team labels the photo as capturing a “contact near Reull Vallis,” a 1,000-mile-long Martian canyon that flows down the eastern slopes of Hellas Basin, the death valley of Mars.
What I see isn’t a geological contact but a complex jumble of odd-shaped depressions and mesas, surrounded by an eroded surface that seems squashed and deformed by some process. If this is all we had to go on, I would simply label this as another “What the heck?” image on Mars and move on. However, the larger context of the overview map helps explain it all, at least as best as we can explain using orbital data.
The white dot on the overview map to the right marks the location, located in the upper half of Reull Vallis and focused on a short but wide tributary that flows northward into the main east-to-west channel. The arrows show the glacial flow direction, and in the inset those arrows I think provide an explanation for the jumbled features in the picture above.
Reull Vallis is essentially a glacial river, flowing roughly downhill from the east to the west into Hellas Basin. At this location the channel widens on the south so that an eddy can form at the outlet point of this side tributary (as indicated by the arrows). That eddy however impinges on the southeast-to-northwest flow of the tributory. The result is that the tributory’s flow is disturbed, resulting in the jumble we see in the picture above.
None of these glaciers are likely active at this time, however, as can be seen by dark slope streaks flowing down the main channel’s north interior cliffs. If the glacier was flowing those streaks would likely be distorted. Instead, they go straight downhill.
This eddy however illustrates why glaciers might possibly explain the many riverlike channels on Mars, rather than flowing liquid water. Though glaciers work very slowly, on Mars they have endless time to do so, as the temperature is almost never above freezing. And since there appears to be plenty of surface or near-surface ice on the planet, especially above 30 degrees latitude, that ice has had the opportunity to do a lot of carving.
The eddy shows the glacier can act just like a river, though much slower. Given enough time and enough ice, there really is no reason that glacial ice can’t carve out channels similar to the channels that rivers carve.
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