Enclosed Martian canyon, filled with ice

Chronological Encyclopedia of Discoveries in Space cover

After being in print for twenty years, the Chronological Encyclopedia of Discoveries in Space, covering everything that was learned on every single space mission in the 20th century, has finally gone out of print.

I presently have my last four hardback copies available for sale. The book sold new for about $90. To get your own autographed copy of this now rare collector's item, please send a $120 check (which includes shipping) payable to Robert Zimmerman to

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"Useful to space buffs and generalists, comprehensive but readable, Bob Zimmerman's Encyclopedia belongs front and center on everyone's bookshelf." -- Mike Collins, Apollo 11 astronaut


"The Chronological Encylopedia of Discoveries in Space is no passionless compendium of information. Robert Zimmerman's fact-filled reports, which cover virtually every spacecraft or probe to have ventured into the heavens, relate the scientific and technical adventure of space exploration enthusiastically and with authority." -- American Scientist

Ice-filled canyon on Mars
Click for full image.

Cool image time! The photo on the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter on November 21, 2019. The uncaptioned image was simply entitled “Ice-filled Graben.”

The location is on the lower flanks of the giant volcano Alba Mons, which in itself sits north of Olympus Mons and the volcanic Tharsis Bulge. The canyon is called a graben because it was formed when a section of the crust slips downward along parallel faults. It does not have the features of a rill, or lava flow, as it starts and stops suddenly. It probably formed due to the rise of the volcano, pulling apart its flanks along faults, causing some sections then to slip downward.

How do the scientists know this is ice-filled? I suspect they have other data that indicates the presence of water, but there are also clear features inside this canyon that resemble the glacial features found elsewhere on Mars. For example, note the parallel lines near the canyon walls. These indicate past surface levels as well as layers within the ice from cyclic climate processes. The line of pits along the southwest wall, where the surface gets more sunlight, also suggests that this sunlight is causing more ice to sublimate away.

Finally, the graben is located at 46 degrees north latitude, definitely far enough north for such ice to exist, based on ample other research.



  • Lee S

    Very cool image!!! Yet more proof that all the “missing water” is still right there… Pretty much all over Mars… Which bodes well for when we decide to colonise our red neighbor!

  • Lee S

    On a side note…. Scrolling along the full sized image, several distinct, separate strata are visible… Layers of ice separated by what seem to be boulder beds… The fairly uniform strata of ice that produces the “dark streak’s” on the side of craters and scarps have been discussed here, but I’ve never seen multiple, very distinct geological layers like those exposed here…
    I understand geological strata here on earth…. But can’t wrap my head around such distinct layering involving ice, then rock ( with big chunks of said rock!), Then ice again… In multiples.
    As you have often said Bob, Mars is alien, and we really have no idea how it’s geology occured… But this really baffles me! Does anyone have any ideas?

  • Lee S: I have noted repeatedly in my posts the known importance of Mars’s cyclical changes in its inclination to the Sun, ranging from 25 to 60 degrees. Increasingly it appears this cycle is of central importance in creating these layers, combined with other events such as volcanic eruptions laying down ash.

  • Lee S

    I get that Bob, my musing is more regarding the acctual make up of the rocky strata… It would be a fair guess that they are volcanic in origen given the location… But those are some mighty big chunks of rock! This gives rise to the musing of what a violent eruption would look like in lower gravity and thin atmosphere….
    I’m also guessing the dust covered top ice layer is pretty old, given the amount of craters, although the rough looking terrain a little further back must be very young as there are almost no “fresh” craters…
    Definitely one of the best “cool image”s you have posted Bob… It sets all my amateur geologist spider senses tingling!
    I’m now off to do a search for how to date Martian terrain by crater count. The date of the latest ice layer will be insightful on many levels.. when was the volcano last active? How long between activity? And the deposition rate of ice?

  • Lee S

    I’m sorry for posting all my thoughts as they occur here…. But this pic has led me down a huge rabbit hole…. I forgot to consider that warm periods would of course result in the formation of distinct strata of solids… I see the same effect every spring, as the piles of snow plowed off the side of the roads melt, the gravel deliniates into distinct strata. This doesn’t alter the fact there are some bloody big lumps of rock in this picture… Absolutely fascinating!

  • Lee S

    The only papers I can find on the subject are all behind paywalls…. If anyone has an ICARUS account and would not mind sharing a pdf with me…. I would be extremely greatful… ( I long for the day I can afford a subscription there…. It’s where all the good stuff gets published!)

  • Lee S: Do some searches on the Google scholar search engine. You will have some success.

  • Lee S

    Thanks Bob!!! I was not even aware of this resource! I have an even bigger rabbit hole to fall down now!!

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