New NASA Administrator Michael Griffin said on Monday he might consider letting the space shuttle return to flight even if an independent panel has not finally approved some safety improvements. Griffin, a rocket scientist who was confirmed by Congress last week to head the U.S. space agency, said NASA's managers will have the final say on whether shuttle Discovery lifts off during its scheduled launch window from May 15 to June 3. Asked at his first news conference if he would allow Discovery to fly despite some reservations by the independent Stafford-Covey Commission, which monitors NASA progress on safety recommendations...