Not long after the Apollo 11 landing on the moon, a professor at Princeton University asked one of his classes, "What is the best way for human beings to live off of Earth?"

At the time, most people assumed the answer would be a planetary surface, like Mars, or perhaps the moon. Gerard K. O'Neill and his class turned this assumption on its head by developing the idea of free standing space settlements built from extraterrestrial materials and set between the Earth and moon or the Earth and the sun.

At these Lagrange Points, especially L5, as it became known, the gravity of two large bodies like the Earth and the sun are perfectly balanced and whatever is at that point will have an enviable stability even though it is apparently floating in free space.

This insight led to the creation of the Space Studies Institute (SSI), which was active in the 1970s and 1980s, and became fertile ground for many innovative ideas about space exploration and development. Many of those of us who became "space advocates" considered ourselves to be "Gerry's Kids," in honor of his great influence on us. An activist organization, the L5 Society, flourished for several years as an offshoot of SSI.

We should bear in mind that O'Neill's vision for space settlement embodied a strong environmental component. He advocated moving all heavy industry off of the home planet into space, and he also supported the use of space-based solar power satellites to bring the sun's energy to everyone on Earth. These were positive side effects of the main theme of human settlements of up to 10,000 people in free space.

(To be continued)

Copyright, Frank White, 2016, All Rights Reserved.

The Overview Effect: Space Exploration and Human Evolution, AIAA, 2014, www. amazon.com