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.

Volcanic vent on Mars

Overview of Arsia Mons pits

To understand today’s cool image we really should start from a distance and zoom in. The overview map to the right focuses in on the two southernmost giant volcanoes in the string of three that sit to the east of Mars’ biggest volcano, Olympus Mons, and to the west of the planet’s biggest canyon, Valles Marineris.

The black dots mark the locations of the many high resolution photos taken by Mars Reconnaissance Orbiter that I have featured previously on Behind the Black. Many are isolated openings with no related geological features. Others appear to be skylights into a more extensive lava tube, hinted at by either a continuing surface depression or a series of similar skylights.

The white dot marks the location of today’s cool image, about 350 miles south of Arsia Mons’ caldera.

Mosaic of volcanic vents
Click here, here, and here for original images.

High resolution image of vent
Click for full image.

The first photo to the right is a mosaic made from three MRO context camera photos. The downhill grade flows to the south. This entire smooth surface is probably a lava flood plain, material that was discharged from Arsia Mons more than a billion years ago when the volcano was active. That the volcano was able to deposit this much lava 350 some odd miles from its caldera illustrates both how powerful the volcano was as well how different lava flows are in Mars’s weaker gravity. They can go farther, and more quickly before they freeze.

Winding through this volcanic plain are three meandering depressions, with the top two each beginning with a deeper sinkhole, as if some liquid, likely lava, had poured out of that deeper opening and as it flowed southward it carved the meandering hollows before disappearing underground again only to pop up later out from the next deep sink.

When the flow reached the southernmost and deepest pit it seems to have no longer flowed directly south in a line. Instead, if you look close you can see what looks like an flow spreading outward from that pit in a southerly direction, but in a wide dispersed manner.

The last picture to the right, rotated, cropped, and reduced to post here, was taken on August 31, 2021 by MRO’s high resolution camera of that southernmost pit. The second image to the right is that same pit, brightened enough so that the details within the shadows can be seen. Based on this imagery, it appears that there are no openings or skylights into voids below, such as a lava tube.

Thus, the meandering depression in the mosaic indicate the existence of an underground lava tube, but the available information suggests it is mostly filled.


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  • Greg the Geologist

    The different behavior in flow of Martian lava may also result in geometry of lava tubes that differ from earth ‘tunnels’. For example, the tubes may have width to height ratios that are dissimilar from terrestrial lava tubes. That may have implications for use of lava tubes as shelter during future exploration.

  • Greg the Geologist:

    Curious for your take on the ” geometry of lava tubes ” vis-a-vis terrestrial ones. I have seen, and walked in, lava tubes in Hawai’i and the Northwest US. I have seen subsided volcanic flows in Hawai’i, and understand that lava is full of gas, and when cooling, releases that gas, so the flow subsides a bit.

    It seems that with 0.3g and (let us assume) a comparable amount of gas in solution, the tubes would be much higher than Earthside ones, but maybe the same width?

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