Ice-filled crater on the Martian north polar ice cap
Click for full image.
Cool image time! The photo to the right, cropped to post here, was taken on September 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows a very distinct impact crater on top of the layered deposits of ice mixed with dirt that form the bottom layers as well as surround the visible north pole ice cap on Mars.
I purposely cropped the high resolution image so that the crater is off center to show the dark streaks that appear to blow away from the crater to the northwest, west, and southwest. This asymmetric pattern suggests the wind direction at this location generally flows to the west, but the pattern might also be caused by lighting effects. The location is at 82 degrees north latitude, and the Sun was only 31 degrees high when the picture was taken, causing long shadows. Also, in the full image, you can see a whole strip of similarly oriented streaks, suggesting that these are slope streaks descending a slope going downhill to the northwest.
The overview map below also provides important information about this location.
The yellow cross indicates the location of this small 500-foot-wide crater. For most of the ice cap, the descent down from the icy upper layers (generally green on the map) to the dirtier layered deposits (trending to blue on the map) is steep and abrupt, a cliff where orbital images routinely capture avalanches in the spring, as they occur. At this location however that slope going down to the west is more gentle, with only a few relatively small and gentle steps downward. This crater happens to be located along one of those steps, which might explain the northwest pointing streaks.
Note that the ice in the crater might not be water ice. At this latitude each winter a mantle of dry ice snow covers everything, only to sublimate away when the Sun arrives in the spring. It is possible that this ice is dry ice that has not yet disappeared.
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 photo to the right, cropped to post here, was taken on September 18, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and shows a very distinct impact crater on top of the layered deposits of ice mixed with dirt that form the bottom layers as well as surround the visible north pole ice cap on Mars.
I purposely cropped the high resolution image so that the crater is off center to show the dark streaks that appear to blow away from the crater to the northwest, west, and southwest. This asymmetric pattern suggests the wind direction at this location generally flows to the west, but the pattern might also be caused by lighting effects. The location is at 82 degrees north latitude, and the Sun was only 31 degrees high when the picture was taken, causing long shadows. Also, in the full image, you can see a whole strip of similarly oriented streaks, suggesting that these are slope streaks descending a slope going downhill to the northwest.
The overview map below also provides important information about this location.
The yellow cross indicates the location of this small 500-foot-wide crater. For most of the ice cap, the descent down from the icy upper layers (generally green on the map) to the dirtier layered deposits (trending to blue on the map) is steep and abrupt, a cliff where orbital images routinely capture avalanches in the spring, as they occur. At this location however that slope going down to the west is more gentle, with only a few relatively small and gentle steps downward. This crater happens to be located along one of those steps, which might explain the northwest pointing streaks.
Note that the ice in the crater might not be water ice. At this latitude each winter a mantle of dry ice snow covers everything, only to sublimate away when the Sun arrives in the spring. It is possible that this ice is dry ice that has not yet disappeared.
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
My teenagers’ comment:
Mars has a pimple! (been a long day, had to share the humor)