NASA Ames Research Center
In 1975 a research group led by Princeton professor Gerard O'Neill conducted a 10 week study of future space colonies. The NASA-sponsored research and the paper born of it was given to artists Rick Guidice and Don Davis, commissioned to illustrate the fantastical and as yet unrealized concepts.
NASA Ames Research Center
O'Neill's team settled on three potential designs for the future space stations: the Bernal Sphere, the Toroidal Colony (pictured) and the Cylindrical Colony. Potential capacity ranged from 10,000 people to one million, and featured circular designs which rotated to generate artificial gravity.
NASA Ames Research Center
The Cylindrical Colony, the most spacious of O'Neill's concepts, had huge windows fitted to allow light to filter through to the landscapes within. The design, later dubbed the 'O'Neill Cylinder', was riffed on in Christopher Nolan's intergalactic blockbuster "Interstellar" forty years later.
NASA Ames Research Center
The Bernal Sphere was first proposed by John Desmond Bernal as far back as 1929, with O'Neill's team adapting the half-century old idea. Shrunk down to 500 meters wide they proposed a highly-curved living surface that featured a "crystal palace" for agriculture and light reflected in via windows near the poles.
NASA Ames Research Center
O'Neill in a paper presented to NASA uses 1990 as a hypothetical start date for a space colony, with the team drawing up a number of potential costs for construction and transportation -- even the volume of livestock each station would need to ship in.
NASA Ames Research Center
Rick Guidice's painting of a cutaway of the Bernal Sphere also shows some of the huge solar arrays required to power the station and its rotation.
NASA Ames Research Center
Despite the futuristic technology required to put such a massive structure in space, all of the artwork from Guidice and Davis shows lush green landscapes -- a far cry from the reality of the International Space Station today.
NASA Ames Research Center
O'Neill suggests that the compact living area of the Bernal Sphere could be offset with separate agricultural modules, spacious enough for industrial-scale farming.
NASA Ames Research Center
Don Davis' illustration of a Cylindrical Colony imagines what a solar eclipse would look like from space, featuring two columns of land hidden from the sun altogether experiencing and night time.
NASA Ames Research Center
Davis depicts a construction crew piecing together a Bernal Sphere complete with houses, grass and rivers, seemingly unscathed by the vacuum of space.
NASA Ames Research Center
The Cylindrical Colony was never envisaged a solitary structure, instead orbiting with a partner.
NASA Ames Research Center
A Bernal Sphere with tilted arrays to maximize exposure to the sun.
NASA Ames Research Center
An exterior view of a Toroidal colony, featuring a giant tilted mirror providing sunlight to the interior surface of the ring.
CNN  — 

It’s early evening and you’re with friends, enjoying a drink or two. The sun is shining after all and it’s been a long week.

The river nearby shimmers in the light. You follow its course, your eyes gradually moving up, up, over your head and then down to the other side. Eventually the water meets in a perfect circle, back where you began. Everything is as it should be. You’re a resident of a Bernal Sphere, floating on the far side of the Moon – you’re used to the artificial gravity by now.

As retrofuturist artwork goes, few reach the outlandish heights of Rick Guidice and Don Davis, commissioned by NASA in 1975 to illustrate potential space colonies.

The designs sprang from the mind of a team at the NASA Ames Research Center, spearheaded by Gerard O’Neill, a Princeton professor given grants by the American space program to conduct a ten week study into off-world structures.

Working with architects, researchers, engineers and scientists in Mountain View, California, O’Neill assessed whether his ideas were feasible, eventually drawing up three concepts to present to NASA: the Bernal Sphere, the Toroidal Colony and the Cylindrical Colony.

Each used centrifugal force to generate artificial gravity, reflected in their circular designs and vast solar arrays to power their rotation. Inside verdant landscapes offered comfortable living in Modernist homes.

Bauhaus structures popped up among lakes and forests; elsewhere whitewashed villas and terracotta patios brought Ionian charm to the cold vacuum of space.

NASA Ames Research Center

The largest concept, the Cylindrical Colony, had the potential to hold a million people at a time. For all intents and purposes, they were like Earth – only turned inside out. O’Neill speculated that with the right technological developments, construction could begin as soon as 1990.

To view the designs with skepticism is to forget the milieu in which they were created: the last manned mission to the Moon was three years previous and Skylab, the United States’ first space station, was orbiting Earth. The space shuttle program, a giant leap which promised so much, was only around the corner.

The progress of mankind’s space programs must have been a crushing disappointment for O’Neill, who died in 1992. He aimed for lush vistas, but in truth we’ve only just learned how to cultivate lettuce. It will be a while before our space stations have room for combine harvesters – even longer, you’d expect, before you can hang glide inside of one.

Forty years on, O’Neill’s designs continue to intrigue, and have inspired numerous derivatives. Perhaps the most high profile was Cooper Station, a satellite seen in Christopher Nolan’s “Interstellar” – a compact version of the Cylinder Colony, later dubbed the “O’Neill Cylinder”.

It may yet be centuries before an object the size of O’Neill’s colonies is ever constructed in space. For now we’ll have to live with the images of what might have been – and what, just possibly, might still be to come.