Former astronaut Sally Ride may be the next big name to quit the nation’s top arms control center, putting pressure on Stanford University to change its policy on professorial appointments. Ride has refused all requests for interviews since joining the Stanford Center for International Security and Arms Control last year. But she did give a colleague, nuclear scientist Theodore Postol, permission to talk on her behalf. Postol said Ride, a Stanford alumna in physics, is looking for positions elsewhere. “She has a wide range of contacts and is using those to assess other avenues,” said Postol, who is also thinking about quitting the center. Sidney Drell, the center’s co-director, resigned earlier this week after complaining that the center could not appoint its own professors because it is not a bona fide university department.