It doesn’t take much mass, just a fleck of paint, to punch a hole into a satellite or an intercontinental ballistic missile. This week’s guest thinks the technology for an AI-controlled space-based kill vehicle, that is also small and lean enough to make room for the fuel needed for speed, is close at hand if the Department of Defense wishes to seize it. Laura Winter speaks with Arno Ledebuhr, a physicist, who worked on the Strategic Defense Initiative’s space-based ballistic missile defense system Brilliant Pebbles, at Lawrence Livermore National Laboratory, under Lowell Wood and Edward Teller.