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

Lozenge-shaped hole in Martian crater

Hole in crater floor
Click for full image.

Cool image time! The photo to the right, rotated, cropped, reduced, and enhanced to post here, was taken on June 7, 2021 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The left image shows what the scientists have dubbed a “lozenge-shaped depression” in the middle of an unnamed 60-mile-wide crater in the southern cratered highlands of Mars. The right image shows the same exact depression, but I have brightened the photo in order to see the details in the shadowed depression.

Though the image is inconclusive, the bottom of the darkest spot in that depression cannot be seen, suggesting it could be an entrance into a larger void below.

Even if there is no voids below, why is this depression here? What caused it? The wider view of MRO’s context camera below might give us a hint.

Context camera image
Click for full image.

The white box indicates the area covered by the photo above. The crater’s north and south rims can be seen at the top and bottom of the photo.

At about 28 degrees south latitude this crater is not expected to show much evidence of ice in its interior, and that generally appears to be the case, based on the visual look of the crater floor. If the crater floor had buried glacial fill, you would expect at this latitude to see more erosion features and some bedrock, as seen by a similar crater at a slightly higher latitude highlighted as a cool image in October 2020. The floor’s smoothness suggests instead that we are looking at bedrock, similar to a different crater floor featured in a cool image in August, 2021.

However, if you look closely at the two interior crater in the crater’s northern quadrant you can see what looks like a splash aprons surrounding each, the kind of apron you see often surrounding craters in the northern mid-latitudes, where there is much evidence of near surface ice.

Such aprons however could instead be impact melt and thus volcanic in nature, not the result of melting ice.

If there is buried ice here at this latitude, it would have to be underground to prevent it from sublimating in the warmer equatorial temperatures. The depression suggests that there might an ice layer below ground, and that it might even be sublimating away to leave cave voids behind. That lozenge-shaped depression on the surface could thus be a sinkhole entrance as well as the outlet in which that gas is escaping.

All guesses on my part. What reinforces my hypothesis to my eye is the look of the other small interior craters close to the depression. Though they do not appear to have aprons, they also appear to have impacted into something somewhat soft, like ice.

If this crater has a subsurface ice layer, it would be the lowest latitude such a thing has been identified, and would strengthen the possibility that future colonists will be able to find mineable underground ice practically anywhere on the Martian surface.

Any papers relating to this depression will likely be published in a year or so. Stay tuned. The data from the Martian orbiters continues to make Mars more and more enticing.

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

One comment

  • Jay

    The crater looks like a dried mud hole and the lozenge (looks like an opened pea-pod to me) looks like a sinkhole. I would love it for Ingenuity to explore that.

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 *