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A half-mile high Martian cliff on the verge of collapse

A half-mile Martian cliff on the verge of collapse
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken on December 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows erosion gullies coming down off a mountain side, just north of a massive cliff that I estimate to be around 2,000 to 3,000 feet high.

Note the north-south-trending cracks. These suggest that this entire half-mile-high cliff face is slumping downward, cracking as it does so. The cracks at the start of the high flat-topped thumb-shaped mesa near the image bottom are especially intriguing. They suggest that this entire mesa might eventually separate and give way.

There is a specific reason this cliff face is slumping, as shown in the overview map below.

Overview map

The red dot in the northwest quadrant of Argyre Basin, just inside the region outlined in white that is labeled glacier country, marks the location of this cliff. The latitude is 45 degrees south.

This cliff is therefore located in a part of Mars where lots of near surface ice and glacial features have been found. In fact, in the full original image there are a number of glacial features, though in truth everything here appears impregnated with ice.

The thumb-shaped mesa is therefore likely not very structurally strong, depending on temperatures. Every time the temperature rises above freezing — though a rare event — it weakens it. Cracks form, and gravity pulls it downward to the west.

Eventually, that seasonal pull will succeed in collapsing the entire mesa in one giant landslide.

Side note: Right now the news in space is relatively light. There are lots of press releases about things that “might happen”, “could explain”, or are “future possibilities,” but few about actual achievements or developments. I generally try not to report on the former, which are mostly puff pieces, and instead focus on the latter, which tell us where the true progress in space is taking place.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!


From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.


“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.


All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.


Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.


  • Ken

    Hi Robert,

    I think either you mistyped the year, or else the MRO has capabilities I wasn’t aware of ;)

  • Ray Van Dune

    Since you tacitly acknowledge that there’s not too much to write about, may I suggest a couple of discussion topics?
    1. Recently I saw an old clip from United Launch Alliance that completely dismissed booster re-landing concepts. What changed? What SpaceX engineering breakthroughs made it possible, or was ULA just unimaginative and/or shortsighted?
    2. What might the next generation of rockets beyond Starship-Superheavy look like? Will they be even bigger? Smaller? Will they stay in space or return to Earth periodically. Will capsules flourish, or integrated ships like Starship? What the heck is the use of Orion if it can’t go beyond the Moon, but can’t land on it either? How long until we have nuclear propulsion? What will be the next stop after Mars?

    Pardon my impertinence, but if you put together some thoughts on these, they could become interesting ongoing threads.

  • Ken: Thank you. Typo fixed. This is a common error I make near the beginning of the year.

  • Ray Van Dune: I would love to see that ULA clip. Can you provide a link?

    I have been thinking of expanding my final paragraph into a longer post, discussing the modern journalistic practice of rewriting all press releases with no thoughtful skepticism. I hope that will please you. :)

  • Ray Van Dune

    Bob, here is how ULA was gonna show us how to make spaceflight cheaper. Be sure to see the animation at the end about how returning the whole booster won’t work!

  • Ray Van Dune

    Ps. I found the above video when I was looking for the definition of the SMART reuse concept: “Sustainable, Modular, Affordable, Reuse Technology”.

    A few weeks ago, I hypothesized here that it had probably evolved to a “Don’t Understand how to Make it Better” concept.

    It seems to me that ULA likely never appreciated the value of booster reuse because under a cost-plus regime, the government paid for it, so it was not a big item. The accountants knew the cost because they had to pass it on, but the engineers… eh, whatever it takes.

  • Ray Van Dune: Heh. That video, from 2015, now is somewhat embarrassing for ULA, specifically when the engineer talks about how much more cost effective SMART will be versus vertical landing. More than 7 years later, SpaceX has proven this assumption wrong repeatedly, and ULA has yet to implement SMART.

    The company has successfully done a test return using the inflatable heat shield, but as of now, it looks like it will still be years before Vulcan’s first stage engines will be reused, if at all.

  • Jeff Wright

    To Ray- I am surprised the big shipyards haven’t pushed for Sea Dragon.

  • Richard M

    Hello Ray,

    I enjoyed the top comment, from Scott Manley: “I’m not convinced until these guys can deliver a working example of recovery in Kerbal Space Program.”

  • Richard M

    More than 7 years later, SpaceX has proven this assumption wrong repeatedly, and ULA has yet to implement SMART.

    107 consecutive successful Falcon 9 landings, as of last weekend!

    Tory Bruno eventually shifted his argument to saying that it might be possible that it made sense for SpaceX, but the lower cadence that ULA was anticipating for Vulcan would not close the business case. But now that that they have all those Kuiper launches on the manifest, they’re going to have to be launching at least twice a month, too. Suddenly, it looks like an opportunity missed.

    Especially with all these new medium/heavy class launchers with partial or full reusability (Neutron, New Glenn, Terran R) in development.

    But I guess they can drive off that bridge when they come to it.

  • Ray Van Dune

    What I really don’t understand is why NASA would pay Lockheed billions of dollars to develop an upgraded version of an Apollo capsule that could not fly beyond the moon, but could not land on it either, and cannot be launched except on a rocket that is so expensive it can’t fly more than once a year? Even US Senators can do basic math, right?!

    … right?

  • Richard M

    Even US Senators can do basic math, right?!

    Unfortunately…they actually can.

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