The follow is from the book summary of Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets:

hollow out asteroids to transform them into livable habitats for billions of space-bound homesteaders

Since the book is not publicly searchable, I can not easily find any more specificity on this idea. As a reference request, I would just like to ask what the general concept prescribed by this book is.

By that I mean, is the author of this book proposing to use asteroids as radiation shielding, a construction material source, as the vessel for a pressurized rotating habitat, or something else? All of these concepts have been proposed in other contexts, and there's quite a lot of difference between them. I would like to what is proposed in that book.


2 Answers 2


I have a copy of that book -- autographed by J. S. Lewis! Most of the book is factual. But occasionally Lewis will indulge in little science fiction vignettes. He describes an imaginary asteroid hab on page 116. This cycler has a 2 year year period. It passes by the earth each two years. At its aphelion it goes by the main belt.

Cycler 3 is 800 meters long and averages 400 meters in diameter, except for the earth gravity wheel at the waist, which is 650 meters in diameter. Before reconstruction, the parent asteroid (2002 AK) was a carbonaceous asteroid of about half these dimensions and much less regular shape. The interior, originally mined to extract water for use as propellant to time the orbit into resonance, has been further excavated and restructured to permit accommodations…

Meteoroid, cosmic ray, and solar flare proton protection provided by the outer walls are all well in excess of Earth-surface standards. ...

Lewis list some rules for this cycler:

  1. There must be no further extraction of water from the native (asteroidal) regolith on the surface of the cycler. The water content of the surface layer is an integral part of the shielding of the interior against light cosmic-ray primaries and energetic solar protons…

  2. All cycles of the biological elements hydrogen, carbon and nitrogen MUST be closed. Certified manifests of all these elements must be uploaded by all arriving vehicles. Departure manifest must also be filed and reconciled …

I don't want to quote too much. But yes, you have the general idea. I think anyone interested in use of space resources as well as settlement of space should have a copy of Lewis' Mining the Sky Another excellent book by Lewis is Rain of Iron and Ice, also about the asteroids and asteroid impacts.



A combination of radiation shielding and the pressure vessel, methinks. I'm not familiar with that specific book, but you're right; the concept's not exactly new.

The problem with long-term habitation of space is that we're the product of billions of years of evolution in a very specific environment, which so far we've been unable to find anywhere else in the universe. We've found some possibilities, but so far none have been definitively confirmed to possess the key ingredients; a mass no more than about double that of Earth, an oxygen-containing atmosphere, and liquid water (which in turn requires the planet to orbit in the "Goldilocks zone" of its star). Any good possibilities would be several hundred years' journey using current propulsion technologies; most orbital masses in our own neighborhood are either too light, too heavy, too hot, too cold, or didn't have the right mix of stuff. So, instead of trying to terraform nearby space rocks to accumulate an atmosphere (a pointless exercise), or mining our own finite resources on Earth to create habitats, we dig into a rock and make habitable spaces inside.

The idea would basically be to mine the asteroid from the inside out, creating first a network of tunnels and then larger caverns within the rock structure. The entry point into the asteroid can be sealed with an airlock relatively early in this process, and the hollow space filled with an atmospheric mix. The only problem would be finding asteroids with a dense, nonporous composition that won't bleed out the atmosphere we try to introduce over time, located in an area of space that's easy to get to and where collisions are unlikely (the asteroid belt isn't a terrible idea as it's had some 4 billion years to settle down, but it can still be dangerous), and then find some way to get the necessary equipment and atmospheric gases out to it. Nearby asteroids might be found with interior reserves of water ice, or we might harvest comets or even the outer layers of the "ice giants" for water and inert gases. Electrolyze the water to produce oxygen, add sufficient amounts of a relatively inert gas like nitrogen or argon, and add some lights powered by solar panels on the 'roid's surface, and you have a rudimentary space habitat. Build traditional enclosures, or just carve what you like directly out of the rock. As you dig, anything valuable as a building material or for export can be sent back to the Mother Planet. By the time the digging's done, you'll have large cavernous spaces suitable for zero-G heavy industry using materials from other minable asteroids, and hopefully a "freight elevator" airlock system that was originally used to get mining equipment in and rock out, and can now be used to get raw materials in and finished goods out. The asteroid becomes a city in space, developed much the way the American West grew up.

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    $\begingroup$ Seems like a rather significant assumption that the hypothesized asteroid would be made of rock or metal, of sufficient structural integrity to withstand the forces generated by a pressurized internal chamber. Noone really knows with any certainty how solid asteroids are; for all we know, most could be nothing more than loosely packed dust and chunks of ice. To inhabit the interior of an asteroid, wouldn't it be a hard requirement to construct an artificial pressure vessel, and not simply hollow out a space? $\endgroup$
    – Anthony X
    Commented Apr 9, 2014 at 2:48
  • $\begingroup$ There are rapidly rotating asteroids that would fly apart if they were loose rubble piles. From meteorites we know of carbonaceous, metallic, stoney asteroids, many different types. Yes, we'd need to construct pressure vessels. Until space mining and manufacturing are established, the first pressure vessels will be from earth. However asteroidal regolith could be packed around the pressure vessel for radiation protection. Water ice would be a good find as it's great radiation protection, good for life support and can be split into hydrogen/oxygen -- one of the better chemical propellents. $\endgroup$
    – HopDavid
    Commented Apr 9, 2014 at 3:32

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