Not as outlandish as the concepts from the 1970s

Wednesday, September 19th, 2018

Jeff Foust of The Space Review reviews The High Frontier: An Easier Way:

In space, as in other fields, ideas come and go, returning after past failures in the hopes that changes in technology, policy, or economics will allow people to accept a concept they previously rejected. That appears to be the case with space settlements. In the 1970s, “space colonies” were all the rage among space enthusiasts, attracted by the idea proposed by Princeton professor Gerard K. O’Neill that giant habitats, many kilometers in size, would be the best place for humanity to live in space. There were NASA-sponsored studies of space colonies with lavish illustrations of the concepts, and ideas to use such facilities to enable space-based solar power (another idea that comes and goes) and other space industries. But, within a few years the concept faded away, with NASA ending its support and predictions that the Space Shuttle would enable frequent low-cost access to space failing to come true.

In the last few years, though, there’s been a push to bring back the idea, now often called “free space settlements” (avoiding the negative perception many have of “colonies.”) A new book by two space settlement advocates, Tom Marotta and Al Globus, offers an update of sorts of the original space colony concept O’Neill offered decades ago in his book The High Frontier, arguing that such settlements need not be as large and as expensive as O’Neill once thought.

As its subtitle suggests, the authors of The High Frontier: An Easier Way make the case that several changes in the original assumptions that drove the 1970s-era space colony concepts make such settlements more feasible today. One eschews the plan to place settlements at the Earth-Moon L-5 Lagrange point in favor of an equatorial low Earth orbit (ELEO) over the Equator at an altitude of 500 to 600 kilometers. That orbit gives such a facility radiation protection from the Earth’s magnetic field while also avoiding the South Atlantic Anomaly, a major source of charged particles. Doing so, they conclude, drastically reduces the mass needed for radiation protection: from five to ten tons per square meter of the facility’s surface to as little as 10 kilograms.

A second design change is to speed up the rotation rate of the facility needed to produce Earth-equivalent gravity. Previous studies assumed humans could tolerate rotation rates of no more than 1–2 revolutions per minute (RPM), but research suggests people can tolerate speeds of 4 RPM without any long-term consequences. That reduces the diameter of the facility, and hence its mass and cost.

Those changes, coupled with work to reduce launch costs, makes a settlement more feasible — or, at least, less infeasible. An initial concept mentioned in the book, called Kalpana, would be 112 meters in diameter and 112 meters long, weighing about 16,800 metric tons: enough to be carried by a little more than 100 flights of SpaceX’s Big Falcon Rocket (BFR) vehicle, at least according to designs the company disclosed last year. It’s still an expensive proposition, but one not as outlandish as the concepts from the 1970s.


  1. Sam J. says:

    Here’s a mass of papers on just this subject.

    I particularly like this one.

    I think it’s foolish to launch all this stuff from earth. The way to do this is to build stuff on the Moon…slowly. With a small amount of money this could be done but you would have to build from scratch just the way our ancestors did. I mean build lathes, milling machines, etc. from Lunar material. 3D printing from lunar dust. What you would have to carry is a couple of programmable rovers with many arms that could be remotely operated. (Moties!!)One technique he didn;t mention is hypervelocity particle forging. They do this now with airplanes using aluminum. I think it’s been done with steel also. On earth they use air to drive powdered metals at high speeds. When they hit the material they instantly melt, fuse and build up. Just like when you spray paint on a surface. It actually forges the material together from powders.

    With only what was on the Moon you could build most all of what you need. You would have to take a lot of concentrating solar film mirrors to get the heat to start things off and it would probably take a lot of messing around to get stuff to work.

    You’re going to need make steel, aluminum and some sort of batteries or flywheels to get mass electric launchers on the Moon from there you can launch a massive amount of stuff. So you would have a few years of toil but after that it would be a bonanza of materials. I read about a propulsion system that used the solar wind, electric currents and large wire loops to propel the solar wind. Once you have the materials you could make these, launch them and then use the solar wind for fine tuning of where you want to place the materials. A lot of this stuff could be done remotely with telerobots. The key is to have a few million dollars up front and some people willing to drone away at this stuff for several years to get the system up and running.

    One thing I’m adamantly against is having the only thing separating the interior of the habitat from space one pane of glass. I think there should be several and mirrors are used to channel the light through several layers of glass. In between the glass should be a mass of material so if micrometeorites break the glass it will hit shielding . Nothing can hit the outside and directly go inside. Here’s the basic idea where the light is folded,

    I’m confused on exactly how this thing is set up. I see him showing light coming in sideways but if it’s spinning??? Here,

    At 1 RPM there would be a lot of flashing light on and off. I must be missing something. I could see light coming from the dock but then you don’t need the rear portion. What he shows is confusing. I like the folded light path though with shielding in between the interior and exterior. With the inner glass shielded then losing a pane or mirror outside would be no big deal.

  2. Yara says:


    You make a good point on the launching of stuff directly from the terrestrial gravity well.

    I seriously, doubt that any space construction project is going to rely on natural light for anything but solar power. Quite besides the enormous inconvenience of maintaining one very specific orientation with respect to the sun, without the benefit of Earth’s atmosphere you lose the effect of Rayleigh scatter, the phenomenon that makes sunlight look warm, soft, and appealing rather than cold, harsh, and unforgiving.

    Fortunately, some innovative Frenchmen have invented some sort of nano-whatever black magic voodoo technology that accurately replicates the effect with just an ordinary bright LED light source and a thin pane of the aforementioned black magic voodoostuff, enabling the installation of indistinguishable-from-reality seasonally summertime skylights in every room of every floor of any skyscraper, in any laboratory in Antarctica, in infinitely deep underground cities, and yes, in spaceships.

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