Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

Curiosity takes a close look at a Martian cliff

A cliff of Mars
Click for full resolution. Original images here and here.

Curiosity has now moved up and into Maria Gordon Notch, a gap in the mountains of Gale Crater that is about forty feet wide, with a 40-foot-high cliff on its western side and a 30 to 60 foot cliff on its eastern side.

The mosaic above, created from two navigation camera images, looks up at the top half of that western cliff. Note the many many layers, each one of which records some climate or volcanic event in Mars’ geological history. The Mars we see today took a long time and many events to become what it is. Such layers however have not been seen everywhere by Curiosity. Compare for example this layered cliff with the massive outcrop dubbed Siccar Point and looked at closely by the rover in October. In that outcrop the layers were either non-existent, or merged together during some subsequent geological process.

Note also the pond of sand/dust at the center-bottom, nestled in a hollow but sitting almost vertical. That the dust can maintain itself at such an angle illustrates Mars’ lighter gravity, about 39% of Earth’s, which in turn allows for a much steeper angle of repose. That lighter gravity also allows for some sections of rock to stick out more precariously than possible on Earth.

As Curiosity moves through the notch in the next few days, more such cool pictures will become available, and I shall post them.


I must unfortunately ask you for your financial support because I do not depend on ads and rely entirely on the generosity of readers to keep Behind the Black running. You can either make a one time donation for whatever amount you wish, or you sign up for a monthly subscription ranging from $2 to $15 through Paypal or $3 to $50 through Patreon.

Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.

Your support is even more essential to me because I not only keep this site free from advertisements, I do not use the corrupt social media companies like Google, Twitter, and Facebook to promote my work. I depend wholly on the direct support of my readers.

You can provide that support to Behind The Black with a contribution via Patreon or PayPal. To use Patreon, go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation. For PayPal click one of the following buttons:


Or with a subscription with regular donations from your Paypal or credit card account:


If Patreon or Paypal don't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to

Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

Or you can donate by using Zelle through your bank. You will need to give my name and email address (found at the bottom of the "About" page). The best part of this electronic option is that no fees will be deducted! What you donate will be what I receive.


  • dave b

    larger outcrops of solid rock at lower gravity makes sense. The rock has the same strength, but is under less load.

    However if the slope is of loose (unbonded) grains I do not see where gravity makes much difference. Dry fine grained wind deposits (of glacial rock flour in particular) can have near vertical angles of repose on earth. I believe it has to do with grain shape. More jagged shapes can interlock and stack steeper. At least that’s what I remember from a 1980’s geology field trip.

  • Ken Ffanks

    All the science aside, it looks like many a mesa or ridge I would hike past in the American Southwest. Would love to do some bushwhacking there (I assume LNT rules still apply).

  • Alton

    The Cliff looks like a Gorn should be lurking there somewhere … … …

  • Alton: Same thought. The music from that scene starting running through my head . . .

  • These black and white photos of Martian cliffs look like they could easily be scenes from season one of the original Lost in Space 😀

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 *