A shadowed ice patch on Mars
Click for full image.
Cool image time! The evidence coming back from Mars in the past two decades has increasingly suggested that there is a lot of water in that planet’s mid- and high latitudes. In the mid-latitudes the evidence suggests that ice is locked in a lot of buried and inactive glaciers that were laid down during periods when the planet’s rotational tilt, its obliquity, was greater so that the annual seasons were more extreme. During those times the mid-latitudes were colder than the poles, and water was being transferred from the poles to those mid-latitudes.
The image to the right appears to be more such evidence. Taken on March 21, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and cropped and brightened by me to bring out the important details, it shows what looks to be a distinct patch of ice on the south-facing slope of the rim of a large crater. Since this crater is in the southern mid-latitudes (34 degrees south), that south-facing slope generally gets much less sunlight, even in the summer, so any remaining buried glacial ice on that slope will linger for a longer period.
Think of the lingering ice and snow patches on shadowed locations on Earth. Because the Sun does not directly shine on them, they will be the last patches to melt away.
What I think is likely important about this patch are the exposed layers along its edge. These are the spots that are melting first, as they are where the ice is exposed, unprotected by a layer of dust and debris. It is also here that we have a window into that geological history. Even at this resolution you can see that the ice was laid down in layers, meaning that it contains evidence of those repeated climate cycles produced by Mars’ shifts in obliquity.
Those layers even seem to show the same sharp and sudden change from brighter and dirtier layers, as seen in the layers of the north pole ice cap, that occurred about 4.5 million years ago.
How tantalizing. The entire climate history of Mars is sitting there for us to decipher. We need only drill a few core samples and voila! the pieces of that history will start to fall into 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 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 full image.
Cool image time! The evidence coming back from Mars in the past two decades has increasingly suggested that there is a lot of water in that planet’s mid- and high latitudes. In the mid-latitudes the evidence suggests that ice is locked in a lot of buried and inactive glaciers that were laid down during periods when the planet’s rotational tilt, its obliquity, was greater so that the annual seasons were more extreme. During those times the mid-latitudes were colder than the poles, and water was being transferred from the poles to those mid-latitudes.
The image to the right appears to be more such evidence. Taken on March 21, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and cropped and brightened by me to bring out the important details, it shows what looks to be a distinct patch of ice on the south-facing slope of the rim of a large crater. Since this crater is in the southern mid-latitudes (34 degrees south), that south-facing slope generally gets much less sunlight, even in the summer, so any remaining buried glacial ice on that slope will linger for a longer period.
Think of the lingering ice and snow patches on shadowed locations on Earth. Because the Sun does not directly shine on them, they will be the last patches to melt away.
What I think is likely important about this patch are the exposed layers along its edge. These are the spots that are melting first, as they are where the ice is exposed, unprotected by a layer of dust and debris. It is also here that we have a window into that geological history. Even at this resolution you can see that the ice was laid down in layers, meaning that it contains evidence of those repeated climate cycles produced by Mars’ shifts in obliquity.
Those layers even seem to show the same sharp and sudden change from brighter and dirtier layers, as seen in the layers of the north pole ice cap, that occurred about 4.5 million years ago.
How tantalizing. The entire climate history of Mars is sitting there for us to decipher. We need only drill a few core samples and voila! the pieces of that history will start to fall into 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 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
The graph of Mars’ historical obliquity, from a paper you reference in link in this post, shows that Mars’ tilt has varied between 15 and 35 degrees in only a few thousand years. I suppose it’s derived from orbital mechanics that can be determined with extraordinary precision on such time scales. That’s alot of change very quickly. And a phenomena that is unknown of on Earth.
LocalFluff: Yup.
*** Bob, please delete this comment after reading ***
I’m sure you will soon be writing a post about Doug Loverro’s just announced ouster yesterday:
* http://nasawatch.com/archives/2020/05/doug-loverro-wa.html
“Doug Loverro Was Asked To Resign And He Has”
There’s lots of speculation about the reasons, but be sure to check out his own letter to his team:
* https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=50976.0;attach=1915987;image
Rose: I see no reason to delete, even though it is off the topic of this particular post. I have already posted on the main page, though I will add the link to Loverro’s letter that you provide here.