The National Aeronautics and Space Administration has pulled the plug on a $65 million nuclear propulsion research program at Knolls Atomic Power Laboratory, leaving 150 employees in limbo. “NASA and Naval Reactors have mutually agreed to terminate their partnership to work on Prometheus,” as the program was called, a Knolls spokeswoman said Friday afternoon. “NASA has been changing its priorities. I don’t have many details on this,” she added.