If we look at the broader history of technology, we see rare individuals possessing a clear vision of an expansive future created by technologies they studied, designed, and promoted. Pushing beyond speculations, their activities sometimes produced actual things and influenced policy. Just as importantly, these people also built communities and networks so they could connect their radical ideas for the technological future to interested citizens, politicians, and business leaders. This talk explores the activities of two such visioneers Gerard O'Neill and Eric Drexler who advocated space settlements and nanotechnologies in response to perceived threats of eco-catastrophism and planetary limits.

Visioneers and the communities of researchers, futurists, and entrepreneurs they attracted have often existed at the blurry border between scientific fact, technological possibility, and optimistic speculation. Their design, imagining, and promotion form part of a longer chain of technological enthusiasm that has marked much of America's history. Nonetheless, visioneers and their supporters were not immune to the lures of profit, celebrity, and sensationalism. And, as their ideas received wider attention and publicity, they also worked to defend the purity and original goals of their visions from fringe characters as well as mainstream scientists. Finally, considering visioneers as a particular analytical category provides an opportunity to reexamine the uptake and adoption of radical ideas in contemporary technological ecosystems.