Leaving Earth cover

In 2019 I obtained from my former publisher the last 30 copies of the now out-of-print hardback of Leaving Earth. I sold about half of these, and with only a handful left in stock I have raised the price. To get your own autographed copy of this rare collector's item please send a $75 check (includes $5 shipping) payable to Robert Zimmerman to

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

I will likely raise the price again when only ten books are left, so buy them now at this price while you still can!

Also available as an inexpensive ebook!

Leaving Earth: Space Stations, Rival Superpowers, and the Quest for Interplanetary Travel, can be purchased as an ebook everywhere for only $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from my ebook publisher, ebookit.


Winner of the 2003 Eugene M. Emme Award of the American Astronautical Society.

"Leaving Earth is one of the best and certainly the most comprehensive summary of our drive into space that I have ever read. It will be invaluable to future scholars because it will tell them how the next chapter of human history opened." -- Arthur C. Clarke

The strange squashed ridges at the basement of Mars

Squashed ridges at the basement of Mars
Click for full image.

Overview map

Cool image time! The photo on the right, cropped and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on April 9, 2020, and shows the very weird and very packed ridges and layers that are found routinely at the deepest part of Hellas Basin, what I have dubbed the basement of Mars.

Be sure to click on the image to see the full photograph. There’s lots more strangeness to see there. And be sure to read my post in the second link, which highlights a similarly strange set of packed ridges, and where I note:

This is the basement of Mars, what could be called its own Death Valley. The difference however is that unlike Death Valley, conditions here could be more amendable to life, as the lower elevation means the atmosphere is thicker.

The context map to the right shows Hellas, with the location of today’s image indicated by the white box, close to basin’s lowest point, more than five miles below the basin’s rim. Overall the Hellas Basin is about the size of the western United States, from the Mississippi River to the Pacific Ocean. It is believed that the entire basin was created by a single gigantic impact that occurred about four billion years ago when the solar system’s inner planets were undergoing what has been labeled the Late Heavy Bombardment.

The specific process that formed these ridges, dubbed honeycomb terrain by scientists, remains unknown however. There are of course theories, none of which are very convincing. Here’s mine, as outlined in the previous post:

[T]he ripples … are truly fascinating, as it is clear that at the highest peaks erosion has ripped those peaks away, leaving behind a hollow shaped by the ripples themselves. These features remind me of some cave features I have seen, where mud gets piled but by water flow, and then is over time covered with a crust of harder calcite flowstone. Later, water then washes out the mud underneath, leaving the curved flowstone blanket hanging in the air.

Here in Hellas Basin it looks like something similar has happened, except that at these peaks the outside crust got broken away, allowing wind to slowly suck out the material underneath, leaving these ripple-shaped pits. Whether it was liquid water or lava that helped create these features, the geology left behind is both beautiful and intriguing. I wonder at the chemical make-up of the crust as well as the materials below. And I especially wonder if there are water sources buried within Hellas Basin.

You can see more of these strange ripple-shaped pits in today’s image.

I wouldn’t take my theory very seriously, but then, no one is enthused about any of the professional theories either.

Because of the depth of Hellas Basin, however, it has that one significant advantage: the Martian atmosphere is thicker, enough to actually increase the possibility of finding liquid water on the surface. And that thicker atmosphere might also be more amenable to the use of flying airships, thus simplifying transport up, down, and about.

Both facts make Hellas Basin a future target for exploration and settlement. The key is water, which as far as I know so far, has not been as clearly documented within the basin. (I could be wrong however, or further research might find it.)

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.


  • A. Nonymous

    Is there a reason SpaceX hasn’t been looking at Hellas? Is the basin floor too irregular for landings (or at least large-scale development)? I’ve been thinking for years that it seemed like the best place to set up shop; the only downside is that you almost have to use a suborbital hop to go anywhere *else* for exploration.

  • A.Nonymous: I can posit two reasons Hellas is not SpaceX’s first choice. First, it doesn’t have as obviously smooth a choice of landing sites. Lots of roughness. Second, and more important, the evidence of easily available water is not there. There might be water evidence, but this is unclear or unproven. Arcadia Planitia meanwhile definitely has lots of evidence of water, so much so that many scientists had already picked it as an ideal first human landing site.

  • janyuary

    Searchin?g “ripples” and finding fascinating stuff, have gone back to Feb of last year so far. Had to comment on this one, though — so on Mars you could have a lake the size of the Western US that was deeper considerably than average “deep seas” hundreds of miles offshore on earth, of two, maybe three miles deep. Just … wow!! Wondering how water pressure, at one third the gravity of earth, would affect anything at the bottom of that lake?

    Also find myself humming “Ripple on still water, where there is no pebble tossed, nor wind to blow ….” Fun to play fried fiddle. And I was never even a deadhead ….! Thanks for the inspiring optimistic reading, Robert.

  • janyuary

    Robert — er, *nevermind* …. I am reading about liquid water on Mars now!

    But what a concept … our vast Pacific is “only” about two to three miles deep on average … the idea of a lake the size of the Western US that was five miles deep at its deepest point, is just mind boggling!

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