The edge of Mars’ north polar ice cap
Click for original image.
Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on September 29, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The picture shows what the science team labels as a “fringe of perennial ice.” For this picture, north is down. The white stuff on the top half of the image is that perennial ice, while the dark material at the bottom is likely a mixture of dust and debris that is still impregnated with ice.
Mars is a very icy world. Orbital data now suggests that above 30 degrees latitude there is a lot of near surface ice, though it is often mixed in with the red planet’s ample dust, blown there for eons. This location however shows us a place where that ice is on the surface, and is generally pure.
That does not mean however this will be a good location to establish a colony.
The white dot on the overview map to the right marks the location, just outside the vast Olympia Undae sand dune ocean that surrounds the north polar ice cap. At 78 degrees north latitude this location is very cold and hostile, likely too hostile for the early Martian colonists.
The cap itself is 600 miles across and a little less than 7,000 feet deep. It is made up of many seasonal layers, like the icecaps on Earth, with the bulk a mixture of water ice and cemented dust and sand. The very top layers, dubbed the residual icecap, is about three to six feet thick made up of frozen water having a volume about half of Greenland’s icecap. While this water could sublimate away, data suggests it is, like the icecaps on Earth, in a steady state, neither gaining or losing volume with each Martian year.
The ice here represents the edge of that top layer. At that edge the ice doesn’t disappear in one sharp line. Instead, as you move south it becomes patchy. As you go further south the patches become smaller, and then are gone entirely. This picture looks at the fringe of one such patch.
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, cropped, reduced, and sharpened to post here, was taken on September 29, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).
The picture shows what the science team labels as a “fringe of perennial ice.” For this picture, north is down. The white stuff on the top half of the image is that perennial ice, while the dark material at the bottom is likely a mixture of dust and debris that is still impregnated with ice.
Mars is a very icy world. Orbital data now suggests that above 30 degrees latitude there is a lot of near surface ice, though it is often mixed in with the red planet’s ample dust, blown there for eons. This location however shows us a place where that ice is on the surface, and is generally pure.
That does not mean however this will be a good location to establish a colony.
The white dot on the overview map to the right marks the location, just outside the vast Olympia Undae sand dune ocean that surrounds the north polar ice cap. At 78 degrees north latitude this location is very cold and hostile, likely too hostile for the early Martian colonists.
The cap itself is 600 miles across and a little less than 7,000 feet deep. It is made up of many seasonal layers, like the icecaps on Earth, with the bulk a mixture of water ice and cemented dust and sand. The very top layers, dubbed the residual icecap, is about three to six feet thick made up of frozen water having a volume about half of Greenland’s icecap. While this water could sublimate away, data suggests it is, like the icecaps on Earth, in a steady state, neither gaining or losing volume with each Martian year.
The ice here represents the edge of that top layer. At that edge the ice doesn’t disappear in one sharp line. Instead, as you move south it becomes patchy. As you go further south the patches become smaller, and then are gone entirely. This picture looks at the fringe of one such patch.
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
“For this picture, north is down. The white stuff on the top half of the image is that perennial ice, while the dark material at the bottom is likely a mixture of dust and debris that is still impregnated with ice.”
If North is down, my expectation would be that the LOWER part of the picture is the “perennial ice”, and the UPPER part “…a mixture of dust and debris …”. Or is this exact location perhaps the reverse?
The 6-7 ft of the residual ice cap cannot possess water-ice “having a volume about equal to half of Greenland’s [mile-thick] icecap.” Instead, it’s the 7,000 ft of the entire martian icecap which contains about that amount of water.
Ray Van Dune: Reread the last paragraph. I note that this is part of a patch, showing its northern edge.
Michael McNeil: I got that number from this website put together by Arizona State University for NASA.