A “Bernal Sphere” design for an artificial habitat, though J. D. Bernal’s original idea was quite different from this.

Largely driven by the success of Elon Musk both in creating companies focused on future industries and his ability to effectively communicate this vision, particular his vision of settling Mars, public awareness of and interest in space exploration has grown. Musk’s vision of private space exploration has Mars at its centerpiece, and this has put Mars in the spotlight, not only as a place for human beings to explore, but also as a place that human beings can settle and eventually call their own. Musk’s paper describing his vision for going to Mars was recently published, “Making Humans a Multi-Planetary Species,” which closely follows the presentation he gave at the 67th International Astronautical Congress in Guadalajara, Mexico in September 2016.

For those of us with an enthusiasm for space travel it is all-too-easy to get caught up in this vision, but there is a history of visionary space programs that did not get beyond the drawing boards, or which were realized only fragmentarily. The ambitious space program designed by Wernher von Braun, sometimes called the “Collier’s space program,” because of the series of articles in Collier’s magazine, communicated to the public in an exciting and accessible way what a large-scale and comprehensively conceived space program could accomplish. The von Braun space program, which, like Musk’s vision, also would have culminated in a human journey to Mars, was partially realized by the Apollo program.

The “Collier’s Space Program” of 1952, primarily the vision of Wernher von Braun.

With the US space program buoyed up by Cold War spending on the national prestige afforded by the Apollo program, NASA laid out a visionary program for space exploration, the Integrated Program Plan (IPP), which is discussed in some detail in Think Big: A 1970 Flight Schedule for NASA’s 1969 Integrated Program Plan by David S. F. Portree. This program, like von Braun’s program, included human exploration of Mars as an eventual goal, but the only part of the program realized was the space shuttle: the orphan of a vision that had none of the rest of the vision to carry into orbit.

The IPP vision of space exploration was one predicated upon building an infrastructure for space exploration that would have included Earth orbit, Lunar orbit, a Lunar base, Mars orbit, and a Mars base. If the US had chosen to spend the money, NASA could have built a spacefaring civilization based on this IPP vision — substantially revised as the program was rolled out, no doubt, but with the essential idea intact — but NASA’s funding was cut rather than expanded, and only one component was realized out of a program conceived in terms of multiple components working together.

NASA’s 1969 Integrated Program Plan (IPP)

Wernher von Braun’s space program also would have involved the construction of a considerable infrastructure in space. Very different from this was the vision of Robert Zubrin, who, in his book The Case for Mars, outlined a vision for Mars exploration without the construction of space-based infrastructure. Zubrin wrote:

“Mars Direct says what it means. The plan discards unnecessary, expensive, and time-consuming detours: no need for assembly of spaceships in low Earth orbit; no need to refuel in space; no need for spaceship hangars at an enlarged Space Station, and no requirement for drawn-out development of lunar bases as a prelude to Mars exploration.”

Before Zubrin, and occupying the opposite end of the continuum in terms of space exploration, in the late 1970s Gerard K. O’Neill spelled out in considerable detail a vision of space settlement in which the exploration of planets would be almost marginal. For O’Neill, the idea was to build massive space-based infrastructure that would allow for large numbers of human beings living and working in space, the transition of polluting industries away from Earth’s surface, and the construction of solar power satellites that could supply electricity for Earth. With millions of people living and working in space one would expect that the planets and the outer solar system would be explored, but this is was almost an afterthought for O’Neill, who asked, “Is the surface of a planet really the right place for expanding technological civilization?”

An “O’Neill cylinder” artificial habitat conceived by Gerard K. O’Neill.

I am old enough to have purchased a first paperback edition of Gerard K. O’Neill’s The High Frontier at the newsstand and cigar shop where I often bought science fiction books (I can still remember the pungent smell of tobacco in the store). I was immediately captivated by the comprehensive vision of space exploration and industrialization that O’Neill laid out in this and in other books that I subsequently acquired. T. A. Heppenheimer’s Colonies in Space and Toward Distant Suns also made a big impression on me.

Musk’s Mars vision is more like Zubrin’s and less like that of von Braun or the IPP, but laying out a compelling vision of Mars exploration and settlement, as Musk has done, energizes the space exploration community. I think it is at least partially as a consequence of this that I have been seeing more articles lately that are indebted to O’Neill’s vision of space settlement focused on massive space-based infrastructure, for example, most recently, To colonize space, start closer to Earth: Space X’s Martian ambitions are making people think seriously about colonizing space. But the Red Planet may not be the best place to start the first space settlement by Charlie Wood. Jeff Bezos is said to share this infrastructure-based vision of space settlement.

A “Stanford Torus” design for a space settlement.

While we have yet to build any space-based infrastructure beyond the International Space Station (ISS) and a great many satellites, the Earth-based space infrastructure — by which I mean national space programs, private “new space” enterprises, as well as educational institutions and private research organizations— has grown considerably and may even be poised to bring down launch costs to the point that one or another of these space exploration visions may be realized. We may be on the verge of a spacefaring breakout from our homeworld. (I can hope.)

Reading Charlie Wood’s article mentioned above, I started thinking about some of the practical questions of designing and building artificial habitats in space. O’Neill and his students designed some very large artificial habitats as space settlements. It is an interesting technical question to ask, assuming that basic engineering of space habitats is mastered, how big could we build a habitat with current materials’ strengths? Many other questions are also suggested, which in turn suggests the question as to whether there is any current systematic study of artificial space habitats.

Inside view of an O’Neill cylinder design habitat.

There is already a college course for the study of Martian architecture (cf. You Can Now Take an Entire College Course on Martian Architecture by Karla Lant), so why not a course — or, better, an entire curriculum — devoted to the design of artificial space settlements for human habitation? Is there such a program? Or, say, a program in materials’ science specialized for artificial habitats? If there isn’t, there should be.

Sooner or later there will be specialized architects who only design structures for space (sort of like being a naval architect or a marine engineer, which specialize in the design and construction of structures to be used in the water), and this seems like an obvious opportunity for Earth-based space infrastructure. Maybe the The International Space University (ISU), or perhaps I4IS, with its newly acquired Earth-based infrastructure (cf. ANNOUNCEMENT FROM I4IS: New HQ), could create a curriculum for artificial space habitat architecture and engineering.