The SNAP-50/SPUR Program   Presented at the Third Biennial Aerospace Power Systems Conference, Philadelphia, Pa., September 1-4, 1964 (not preprinted).   Note: This paper presents the status of the SNAP-50/SPUR Program at the time of the AIAA Conference in Philadelphia, September 1964. During 1965, it was decided to disband the Program Office and, instead, transfer responsibility on a basic technology level (as contrasted with a technology demonstration program) to the Livermore Laboratories of the U. S. A