Distances Traveled by our Four Oldest RTG-Powered Spacecraft, DOE Memo to Al Newhouse, Bob Lange, Ed Mastal, Art Mehner, Bev Cook & V. Cassella of DOE. Attached is a copy of letter from Hazel R. O'Leary, Secretary of Energy to Admiral Bruce Demars, Secretary of the Navy dated 5/4/1994, subject: 100 Million Mile Milestone on Nuclear Power. Attached is a copy of letter from President Bill Clinton to Hazel Rollins O'Leary, Secretary of Energy dated 4/25/1994