The Interior of a Bernal Sphere Space Colony.
All images in this article courtesy NASA.

Stanford Torus
Tech Level: 14
Bernal Sphere
Tech Level: 14
O’Neill Colony
Tech Level: 15

Space Colonies take up where Space Stations leave off. More than just outposts or way stations, colonies are full-fledged residences in the Great Dark. Many people may be born and live the balance of their lives on these large artificial cities in space.

Tech Level: 14

A much larger version of von Braun's wheel station was conceptualized in 1975 by NASA and Stanford University, as a means of housing both orbital factories and the personnel needed to run them. What resulted was the concept for the Stanford Torus, a wheel station nearly two kilometers in diameter, 200 meters wide, and capable of holding up to 10,000 permanent residents.

The innermost wall of the torus would be transparent, in order to allow sunlight to enter by means of giant louvered mirrors anchored to the wheel hub. These mirrors can be opened and closed, in order to allow an Earth-approximate day/night cycle. Below this inner-rim skylight would be large open areas holding very normal-looking houses, buildings, and even soil, parks, and hydroponic farms, all designed to provide its inhabitants with as familiar an environment as possible. Rotating approximately once per minute would provide Earth-normal gravity on the interior surfaces, with no great difference in gravity gradients between levels until one enters one of the spokes on the way to the hub. The outermost levels below the habitation level would be dedicated to maintenance, manufacturing, and storage.

Tech Level: 14

A step up in sophistication and livable surface area from the Stanford Torus is the Bernal Sphere, conceived in its current form in the same 1975 study that produced its wheel-shaped cousin. Like the Stanford Torus, it crystallized from earlier science and science fiction sources.

Like the Stanford Torus, the Bernal Sphere is two kilometers in diameter and rotates about once per minute to provide Earth-like gravity. However, as its interior is a sphere rather than a simple ring, far greater surface area can be used by potential colonists. Large circular transparent sections near the rotational hub would allow sunlight to be directed into the interior by means of gimbaled mirrors. Like the Torus, the Bernal Sphere would have most of its internal volume completely open with very Earth-like communities, structures, and parks sculpted into its innermost surface. However, as one moves up the sphere from the rotational equator to the hub axis, perceived gravity would steadily decline. Thus this kind of colony would have varying high-gravity and low-gravity neighborhoods.

One of the more interesting concepts that arose for Bernal Sphere interior design is to have an open "river" ringing the entire length of the Sphere's equator, which would double as the construct's central water reservoir.

Tech Level: 15

In the early 1970s, Dr. Gerard K. O'Neill, through college courses and his book The High Frontier, began promoting the idea of large-scale construction in space, and of a particular kind of gigantic space station that has since become known as an O'Neill Colony. O'Neill Colonies were included in the NASA/Stanford 1975 study on space colonization. O'Neill Colonies have also become one of the great enduring motifs of modern science fiction, having been seen in dozens of science fiction sources. The current generation probably knows them best from the various incarnations of the Gundam anime series, and from the title station in the TV series Babylon 5.

O'Neill's vision was of large rotating cylinders, from hundreds to thousands of meters across and many kilometers long. The interior would be open and pressurized, with the inner surface holding not only living and working quarters, but soil, forests, waterways, and so on, in essence becoming a large self-enclosed Earth-like ecology. Large gimbaled mirrors would direct sunlight into the interior along transparent strips running the length of the cylinder, closing for eight hours at a time to create an artificial night. Even more than the Stanford Torus or the Bernal Sphere, an O'Neill Colony would have the interior volume to become a miniature version of the homeworld, allowing people aboard to live, work, and even raise families in much the same manner as people on the ground. O'Neill colonies, once up and fully running, could hold hundreds of thousands of residents. The open park-like spaces could be turned into farms, and with strict recycling in place, the station could become virtually independent from Earth.

Inside an O'Neill Colony. The suspension bridge pictured is the same size as the Golden Gate bridge in San Francisco.

O'Neill Colonies are more than just outposts or way stations; they are true residences in the Great Dark. While other stations are usually mentioned as being in near-Earth orbit, O'Neill Colonies are often visualized as inhabiting locations much farther out—geosynchronous orbit, the Lagrange points, even orbiting the moon or other planets. In the centuries to come, they could well become the equivalent of the small towns of the solar system—the modest, sometimes isolated stopovers between the major population centers that would spring up on colonized worlds.


In Print:

The High Frontier by Gerard K. O’Neill

Clarke County, Space by Allen Steele

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Article added 2006