Designing the mission
With all this in mind, I led an internal research project from mid-2017 to mid-2019 at the Southwest Research Institute (SwRI) to study how to implement a Pluto orbiter. The study team included my SwRI colleagues Tiffany Finley, Mark Tapley, John Scherrer, and Amanda Zangari (who is now at Lincoln Labs).
The mission design we created put a New Horizons-scale spacecraft with new instruments into Pluto orbit. It requires one of the massive new, Saturn V-class launch vehicles now in development, a Jupiter gravity assist, and a nuclear electric stage augmented by a chemical propulsion braking stage to reach Pluto orbit.
We studied what kind of payload should be flown on such an orbiter, what kind of orbital tour would be possible, what the main orbiter spacecraft attributes need to be, and how to get such a spacecraft from Earth to Pluto. This study constituted the first, and presently the only, investigation of how to build a Pluto orbiter to follow up on the discoveries of New Horizons.
One of the top breakthroughs was a game-changing solution to the propulsion requirements to tour the Pluto system, which originally added a huge amount of mass to the spacecraft. We discovered that virtually all of the propulsive needs to explore many aspects of the planet and its satellites could be eliminated using targeted close flybys of Pluto’s Texas-sized moon Charon for repeated gravity assists. This is analogous to how the Cassini orbiter toured the Saturn system using the large moon Titan for gravity assists. When we simulated the idea, it worked beautifully, eliminating most of the fuel an orbiter needs to carry.