Scroll down to read this post.


Please consider supporting my work, as I take no advertisements nor accept any sponsors in order to keep the website clean, easy to read, and to avoid any accusations of conflict of interest. Your support leaves me entirely independent, able to say whatever I think while being free from censorship or reprisals.


You can support me either by giving a one-time contribution or a regular subscription. There are five 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
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

Revisiting Mars’ glacier country

Glacial cracks or pits on Mars
Click for full image.

With today’s cool image we return to what I have labeled glacier country on Mars, though this time the image shows a Martian glacial feature that while resembling vaguely such features seen on Earth, has an alienness to it that requires some explanation.

The photo to the right, cropped to post here, was taken on March 24, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The section I have focused on is the floor of a depression with a number of parallel pits, more or less aligned with the packed north-south ridges that cover the entire floor.

Normally, the north-south ridges would suggest repeated glacial flows moving to either the west or to the east. Such movement could over time, cause the ridges to separate, creating the cracks or pits that we see here. The trouble is that the slope of this depression is very unclear. In fact, the wider view below shows that this depression appears mostly enclosed, or if not it does not seem to be flowing in any particular direction.

Glacial depression with pits or cracks

While there is a faint suggestion of a slope down to the west, that is hardly obvious or proven. In fact, the surrounding terrain suggests instead no clear slope at all, with its pits and depressions forming in almost a random pattern. Moreover, the depressions all give the impression that they are filled like ponds with ice. Why then would the ice in these depressions have these repeating north-south ridges, almost like waves?

This region, dubbed Protonilus Mensae, is an area of chaos terrain, random mesas separated by criss-crossing canyons, caused by erosion and typically found in the transition zone between the cratered southern highlands and the northern lowland plains. The image itself is of the floor of one of the wider canyons, just to the northeast of the rim of 85-mile-wide Moreux Crater.

Overview map

The red rectangle in the overview map to the right shows the location of this image. The numbered blue boxes show glacial features that I have previously highlighted:

As I noted in the fourth post,

If you go to the MRO archive of images from its high resolution camera and go specifically to this location (link here), you will get access to all the high resolution photos so far taken of Protonilus. Click on any red box at this archive and you will see a different MRO image that invokes the same glacial features. If I wanted to, I could post a cool glacier image for practically every single one.

In today’s image, we see that sometimes these Martian glacial features resemble what we’d expect on Earth, but at the same time raise questions that need further exploration.

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

Readers: the rules for commenting!


No registration is required. I welcome all opinions, even those that strongly criticize my commentary.


However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.


Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.

Leave a Reply

Your email address will not be published. Required fields are marked *