Charley Kohlhase

Mission design pre-launch, mission planning post-launch

Retired

Knoxville, Tennessee

I loved adventure stories as a child, turned to science fiction as a young adult, studied math and physics at Georgia Tech, often gazed at the night sky and dreamed of one day exploring the planets. After learning the tricks of the trade at the Jet Propulsion Laboratory, I was thrilled in late 1974 to receive a call from Bud Schurmeier, project manager of the Mariner Jupiter/Saturn 1977 mission (or simply MJS77), which was later named Voyager. He offered me the job of “mission analysis and engineering manager.” I would be working with the great team of dedicated people Bud had assembled.

The mission design at that point needed to be redesigned for two reasons. First, the Pioneer 10 and 11 missions had discovered that Jupiter's radiation levels were much higher than previously thought, so we would need to use less sensitive electronic parts and/or cover some parts with tantalum shields. Bud also wanted me to pick trajectories that would allow Voyager 2 to make a second pass at Saturn’s moon Titan if Voyager 1 failed – or continue on to Uranus and Neptune if Voyager 1 succeeded.

In time, we winnowed roughly 10,000 different launch-date/arrival-date possibilities down to 98 to cover the launch period, finally launching Voyager 2 on August 20 and Voyager 1 on September 5 of 1977. That was the Goldilocks year for the launches, allowing us to have great encounters with Jupiter's Galilean moons while also preserving the option to fly the “Grand Tour” on to Uranus and Neptune. Such a unique opportunity occurs every 176 years – so there won't be another chance until 2153.

The greatest scare during launch was booster under-performance for Voyager 1 that left only 3 seconds of burn time in the Centaur tanks before setting off for Jupiter. After launch, John Casani, who was then the project manager, invited me to stay on as “mission planning office manager." This allowed me to interact with Voyager’s worldwide fans in memorable ways including educational presentations to dedicated science teachers, gee-whiz facts to the eager public, and even meeting several of my own heroes.

I had many memorable encounters with personal heroes of mine because of Voyager. I met science fiction authors Arthur C. Clarke and Ray Bradbury, had several meetings with Carl Sagan, spent a full day with astronaut Neil Armstrong, attended meetings with Bill Nye as an adviser to The Planetary Society, worked with computer graphics pioneer Jim Blinn to produce all six Voyager flyby animations, and attended a black-tie evening event with musical composer John Williams. I kept praising him for his brilliant musical scores, while he responded that he could not imagine designing a mission to the outer planets.

Scientists and science fiction writers were naturally drawn to Voyager, as it represented a great voyage to faraway worlds that these people had always dreamed about.