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I am now running my annual July fund-raising campaign to celebrate the twelfth anniversary of the establishment of Behind the Black. For many reasons, mostly political but partly ethical, I do not use Google, Facebook, Twitter. These companies practice corrupt business policies, while targeting conservative websites for censoring, facts repeatedly confirmed by news stories and by my sense that Facebook has taken action to prevent my readers from recommending Behind the Black to their friends.

 

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Bennu tosses particles from its surface routinely

Objects ejected from Bennu
Tracked particles after August 28, 2019 ejection event.

During OSIRIS-REx’s more than twenty months flying close to the Bennu, scientists have found that the asteroid routinely kicks particles from its surface into space, with these events linked to the asteroid’s day-night cycle.

Since arrival the scientists have seen and tracked more than 300 ejection events, with the almost seven hundred objects detected ranging from about an eighth to a half inch in size. Most moved about eight inches per second, comparable to “a beetle scurrying across the ground.”

The image to the right, cropped, reduced, and brightened to post here, comes from the introductory paper of a suite of papers on the subject, published today.

The timing of the events however reveals the most.

As Bennu completes one rotation every 4.3 hours, boulders on its surface are exposed to a constant thermo-cycling as they heat during the day and cool during the night. Over time, the rocks crack and break down, and eventually particles may be thrown from the surface. The fact that particle ejections were observed with greater frequency during late afternoon, when the rocks heat up, suggests thermal cracking is a major driver. The timing of the events is also consistent with the timing of meteoroid impacts, indicating that these small impacts could be throwing material from the surface. Either, or both, of these processes could be driving the particle ejections, and because of the asteroid’s microgravity environment, it doesn’t take much energy to launch an object from Bennu’s surface.

The link includes a cool movie showing the ejections events and the tracked paths of the ejected particles.

Conscious Choice cover

From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

 
Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.

 

“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.

 

Available everywhere for $3.99 (before discount) at Amazon, Barnes & Noble, and 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.

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