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

A spray of Martian meteorites

A spray of small secondary impacts
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken on October 26, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It is what the camera team calls a “terrain sample,” meaning it was not specifically requested by a researcher but was instead chosen by the camera team because they need to regularly take images to maintain the camera’s temperature. When they do this, they try to pick a location that hasn’t been photographed in high resolution previously, and that might have some interesting features. Sometimes the photo is boring. Sometimes they hit pay dirt.

In this case, the photo captured an small impact crater, about 1,300 feet across, surrounded by a spray of secondary impacts. The color portion of the image shows what I suspect are dust devil tracks cutting across a surface that, because of its blue tint, is either rough or has frost or ice within it. At 48 degrees north latitude, the possibility of the latter is high, especially because this location is northwest of the Erebus mountains, where SpaceX has its prime Starship candidate landing zone and where scientists suspect ice is readily available very close to the surface. The overview map below shows this context.

Wide Overview map

This crater’s location, indicated by the black box, is also 250 miles southwest of 74-mile-wide Milankovic Crater, where scientists have discovered numerous scarps with almost pure ice layers exposed.

The spray of small secondary impacts surrounding this small crater in the first image above likely came from the central impact. The central impact however could very well be a secondary impact itself, ejecta thrown off by the bolide that smacked into Mars to create Milankovic.

The hypothesis is reinforced by taking a look at the immediately surrounding terrain.

Context camera overview
Click for full image.

To the right is a wider view, with the white box showing the location of the top image. It was taken by MRO’s context camera. As you can see, this small impact crater is only one of many, scattered across a relatively smooth and flat region interspersed with what look like small volcanoes.

All of the small craters look to be about the same age. Moreover, that there are no large or more eroded craters here suggests that the small volcanoes, which either formed from magma or mud pushing upward, had covered over the older terrain, became inactive, and then the Milankovic impact occurred, showering this region with secondary material.

One last item: Note the nature of the small secondary craters in the first image. All look like the kind of depression you see when you drop a stone into slushy ice. The bright blue color of the material in the secondary craters in the color strip also suggests ice.

This shouldn’t be surprising. At this high latitude, north of what is believed to be a very icy region near the Erebus Mountains, ice should be plentiful, just before the surface.

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.


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