Part 1: The Hammer and the Nail

When I joined the Power and Propulsion Element Mission Design Team in May of 2020 (yes, during the pandemic), it seemed natural that trajectory design work was going on at NASA Glenn. Why wouldn’t it? And of course Glenn Research Center (GRC) was managing the PPE project, that makes total sense right? It wasn’t until a little later, once I became more entrenched in the world of low-thrust trajectories, that I started to realize how unique this project and this team is. And exactly why Cleveland, of all places, is at the epicenter of electric propulsion.

I originally set out to tell the story of the PPE Mission Design (MD) Team. How a research field center of all places became one of NASA’s leaders in low-thrust trajectory design. So much so that GRC was trusted to deliver not only PPE, but HALO as well to the Moon by way of an electric propulsion driven spiral. This story is rooted in the larger history of PPE MD’s parent group, the Mission Architecture and Analysis Branch (known by its GRC organization code, LSM). The branch has its own long history, stretching back to the 1980’s to a group known as the Advanced Space Analysis Office, or ASAO. And here is where the story becomes a beautifully intertwined web of technology, and application.

The ASAO, LSM, PPE MD, and even PPE itself all share a common lineage, tracing back to 1956 and the Lewis Flight Propulsion Laboratory of the National Advisory Committee for Aeronautics. A young and brilliant engineer by the name of Wolfgang Moeckel began researching a relatively new idea, in-space electric propulsion. What began as a few interesting papers quickly grew into the nation’s (and soon the world’s) foremost electric propulsion development program. And so began the arms race between hammer, and nail.

The tricky part about developing the world’s first ion thruster is that no one on Earth really knew how to actually use it. The specific impulse is how high? And the thrust is how low? The engineers at NASA Lewis (later Glenn) had forged the world’s shiniest hammer, now they just needed a nail to use it on.

And so began the co-dependent dance between thruster development, and low-thrust trajectory design. The engines were useless without an in-depth knowledge of how to use them on practical missions. And ever more complex and capable low-thrust missions were impossible without sufficiently mature thruster technologies. The technologist needs the analyst, and the analyst is nothing without the technologist.

I cannot possibly tell the history of low-thrust mission design at NASA Glenn without also telling Glenn’s history of electric propulsion development. The two trace a common heritage through the decades. Through PPE, the Asteroid Redirect Mission, JIMO, Deep Space 1, through countless mission concepts and studies, all the way back to Wolfgang Moeckel and Harold Kaufman in 1956.

It’s a story of triumphs and setbacks. Breakthroughs and cancellations. Dedication, sometimes stubborn dedication, to the promise of a new, unproven technology years ahead of its time. A dream decades in the making, now being realized in the highest power EP system ever put to flight.

This is the story of the EP Mafia.