President George W. Bush said on Friday he intends to nominate Michael Griffin of Johns Hopkins University to head the National Aeronautics and Space Administration. Griffin would succeed Sean O'Keefe, who presided over NASA during the troubled period that followed the Feb. 1, 2003, shuttle Columbia disaster, which killed seven astronauts and brought widespread criticism of the U.S. space agency's "broken safety culture." The shuttle fleet has not flown since the accident and Bush has set out a vision that would replace the shuttles with a new space vehicle meant to take Americans back to the moon and eventually to Mars. Griffin currently serves as Space Department Head at Johns Hopkins University Applied Physics Laboratory outside Washington. Previously, he was president of In-Q-Tel and worked at Orbital Sciences Corporation. Earlier in his career, Dr. Griffin served as NASA's chief engineer and as deputy for technology at the Strategic Defense Initiative Organization. Since O'Keefe's departure in February, NASA's acting director has been former astronaut Fred Gregory. --SP 2349 Local Time 2049 GMT