SpaceX’s acquisition of Swarm pays off with new Starlink thrusters

Earlier this week, SpaceX released more information about new argon Hall thrusters that will power Starlink V2 mini-satellites, an innovation that likely has a lot to do with the company’s 2021 acquisition of Swarm Technologies.

The deal, which closed in July 2021, was an extremely rare move for SpaceX. Swarm – which manufactures and operates ultra-small satellites for IoT devices – remains the company’s only acquisition in its 21-year history. It was also notable because, relatively speaking, Swarm was still a fairly young company: when the deal was struck, the startup had about 30 employees, 120 sandwich-sized satellites in orbit, and had just launch its flagship product earlier that year.

But in the space industry, talent is king, and it seems SpaceX has benefited enormously from absorbing Swarm’s team.

Swarm’s two co-founders, Sara Spangelo and Benjamin Longmier, have been named senior directors of satellite engineering at SpaceX. Both are part of Starlink’s direct-to-cell team, which aims to leverage the Starlink constellation to bring satellite connectivity to smartphones around the world. But Longmier also says on his LinkedIn that he leads Starlink’s electric propulsion group, which is the group responsible for engineering the new argon Hall thrusters announced this week.

Hall thrusters themselves are nothing new. The name refers to decades-old general propulsion technology. Essentially, Hall thrusters use a magnetic field to ionize a thruster and produce plasma. Satellites use thrusters throughout their useful life – to adjust attitude, avoid collisions with other objects, or deorbit at the end of life.

The real innovation is in the propellant: argon. Argon is several times cheaper than xenon (the most common and expensive propellant used in Hall thrusters) and krypton (the SpaceX propellant used in Starlink V1 and V1.5 satellites), in part because is more abundant.

“The transition to argon was tricky, but necessary, because krypton is too scarce,” SpaceX CEO Elon Musk explained on Twitter. According to specs shared online, these new thrusters will also generate 2.4 times the thrust and 1.5 times the specific impulse (a measure of how efficiently the unit uses the thruster, relative to the thrust generated) than previous Starlink thrusters.

As early as 2011, Longmier was the lead author of technical papers on electric propulsion systems using argon gas. He has also co-authored other articles on propellants using argon and xenon as a propellant. On Twitter, Longmier said that 556 days passed between the thruster clean sheet and orbit: this would mean that SpaceX would have started working on the thrust around the end of August 2021, very soon after the acquisition of Swarm. Longmier did not respond to TechCrunch’s request for comment.