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My July fund-raising campaign, celebrating the 13th anniversary of the start of this website, has now ended. This was the second most successful monthly fund-raising campaign ever. Thank you again to everyone who has who donated or subscribed. It is difficult to explain what your support means to me.


You can still donate or subscribe to support my work if you wish, either by giving a one-time contribution or a regular subscription. There are four ways of doing so:


1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.


2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.

3. A Paypal Donation:

4. A Paypal subscription:

5. Donate by check, payable to Robert Zimmerman and mailed to
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The outermost edge of Mars’ north polar icecap

The outermost edge of Mars' north polar icecap
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on February 4, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the terminating cliffs of the north pole ice cap of Mars, dubbed Rupes Tenius on this side of the icecap.

At this point the elevation difference of the icecap’s edge from top to bottom is not significant, only about 1,500 feet or so, though this is a very rough estimate. As with all other images of the ice cape’s edge, there are many many layers visible, all indicating a different cycle in the climate history of Mars as its rotational tilt swings from about 11 degrees to 60 degrees over eons.

Moreover, at this point there is likely not that much difference between the terrain on top and the terrain below. Both will be mixed ice and dust and coarse rocks, though the percentages will be shifting towards less ice as we go down.

Overview map

The white rectangle on the ice cap’s left edge on the overview map to the right marks the location of Rupes Tenius, which extends more or less from here to the east, where Chasma Boreale begins.

The edge of the north pole ice cape at the top of this overview map is much steeper and higher then at Rupes Tenius, and is also where MRO has spotted numerous avalanches occurring, as they happen.. At the more subdued cliffs of Rupes Tenius such avalanches have not yet been seen, though it is likely they happen, though not as frequently, and certainly not with as much drama because the cliffs are not as high.

The answer to many questions about the geological history of Mars is locked in these ice cap layers. All geologists need to do is to drill some long core samples into the ice cap, either here or in fact anyone on the cape. A review of that core will then quickly outline that entire geological history, and help explain other geological features everywhere else on the planet.

Genesis cover

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

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