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

Giant wind eddies in the sands of Mars

Wind eddies on Mars
Click for full image.

Cool image time! The image to the right, cropped and reduced to post here, was photographed by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on August 5, 2020. It shows a cluster of the crescent-shaped gullies, apparently carved from desert sand by the prevailing winds.

Those prevailing winds here are from the southwest to the northeast. As the wind blows the sand to the east, it hits a more solid object, such as a mountain buried in the sand, which forces the wind and the blown sand to go around, much as water passes a boulder in river rapids. That solid object also causes an eddy to form at its face, the wind forced downward and then around and up, carving out the gullies by lifting the sand at the base of that solid object. The result are these crescent gullies, dubbed blow-outs.

The overview map helps explain why there is so much sand here, enough apparently to bury whole mountains.

Overview map

The white box near the center of the map indicates the location of this image. It is in the middle of the Medusae Fossae Formation, the largest ash deposit on Mars, about the size of India and many feet deep. Laid down in many layers over almost a billion years from 3 to 4 billion years ago, this ash field is also thought to be the source of much Mars’ dust and sand.

A survey of all nearby MRO high resolution images finds a lot of these crescent-shaped gullies, all located on the eastern slope of a large 650-mile-long north-south ridge dubbed Eumenides Dorsum and oriented in approximately the same way. My guess is that the temperature differences between the top and bottom of this ridge causes the wind to flow its slopes, thus creating these blow-outs.

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.


  • Lee Stevenson

    You don’t get as many comments on your cool images as the political posts… But I can assure you that they are very much appreciated Bob. Your eye is sharp and your analysis always thoughtful.
    This stuff is literally not published anywhere else, and your hard work is lapped up by this socialist, regardless of any difference in opinion. Thank you.

  • Chris

    Hi Bob

    Are there any theories on why MArs even has prevailing winds from the southwest or from any direction – or why there are any prevailing winds?

  • Chris: Theories exist. I think however that they are based almost always on local conditions, such as what I described in this post.

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