Apollo science and site selection, Apollo Program, Bellcomm, Inc., 1963-1972
Deputy Director, Lunar Programs, Office of Space Science, NASA HQ, 1972-1974
Associate Administrator for Space Science, 1974-1979
Director, National Air and Space Museum, 1979-1982
Director, Goddard Space Flight Center, 1982-1987
Associate Deputy Administrator, Chief Scientist, NASA HQ, 1987-1989
