From the link:
NASA Ames Director Simon “Pete” Worden revealed Saturday that NASA Ames has “just started a project with DARPA called the Hundred Year Starship,” with $1 million funding from DARPA and $100K from NASA.
“You heard it here,” said Worden at “Long Conversation,” a Long Now Foundation event in San Francisco. “We also hope to inveigle some billionaires to form a Hundred Year Starship fund,” he added.
“The human space program is now really aimed at settling other worlds,” he explained. “Twenty years ago you had to whisper that in dark bars and get fired.” (Worden was in fact fired by President George W. Bush, he also revealed.)
But these ambitious projects will need whole new concepts for propulsion, Worden advised. “NASA needs to build a true starship, probably using electric propulsion, probably also using solar energy and nuclear energy.
Microwave thermal propulsion (Kevin Parker)