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
In response to the questions posed on the margins of the referenced letter (copy attached), I have calculated the distances traveled since achieving orbit by our four oldest RTG-powered spacecraft. The first consideration in this calculation is: How far have they traveled in relation to what? Since the Navy milestone distance must have been derived relative to the surface of the Earth, I have also chosen to use the Earth's surface as a reference. I have neglected the rotation of the Earth and
... of the Earth and its travel around the Sun, as did the Navy. As of 29 June 1994, our oldest nuclear-powered spacecraft, Transit 4A, will have been in space 33 years (289,272 hours). We do not know how long the SNAP-3 RTG provided power to the satellite because the telemetry signals were lost soon after the launch. The Transit 4A spacecraft was injected into a 890 x 1000 km near-circular orbit, inclined at 67.5° to the equatorial plane, with an orbital period of 104 minutes. During this time, the satellite will have traveled about 4,767 million miles along its orbital path. This amounts to 166,888 times around the Earth and equals 4,151 million miles on the surface (mean radius of the Earth equals 3,959 miles). The second nuclear-powered spacecraft was Transit 4B, launched on 15 Nov 1961 into a 960 x 1130 km near-circular orbit, inclined at 32.4°, with a period of 106 minutes. The satellite quit operating after about 8 months due to the Starfish nuclear weapon test in space. Transit 4B will have been in space 285,936 hours as of 29 June 1994 and will have circled the Earth 161,851 times. This is a distance of 4,686 million miles along the orbital path or 4,026 million miles on the Earth's surface. Transit 5BN-1 was the third nuclear-powered spacecraft, and the first fully powered by a SNAP-9A RTG. It was launched on 28 Sep 1963 into a 1090 x 1150 km orbit, at a near-polar inclination of 89.9°, with a period of 107 minutes. As of 29 June 1994, it will have been in space 269,568 hours and circled the Earth 151,160 times. It will have traveled an orbital distance of 4,421 million miles and a distance of 3,760 million miles on the Earth's surface.