Zinc instead of xenon: Muon Space fires a metal-fueled Hall thruster in orbit
Muon Space has fired a zinc-propellant Hall-effect thruster in orbit for the first time, potentially slashing propellant costs for satellite operators by more than 99%. The thruster — called Starlight — ignited on July 1, 2026, aboard Muon's SERT-III test satellite, which launched on a Falcon 9 in March. Ground tracking confirmed the burn actually shifted the satellite's trajectory, making this a real propulsion milestone rather than a lab curiosity.
The xenon problem
Most electric thrusters flying today run on xenon or krypton — noble gases that work well but cost between $5,000 and $12,000 per kilogram, per SETS Electric Propulsion. They also need heavy, high-pressure storage tanks that eat into payload capacity and complicate spacecraft design. Zinc sidesteps both problems: it stores as a solid at room temperature with no pressure vessel required, and it costs roughly $7–15 per kilogram. For constellation operators counting hundreds of satellites, that difference is enormous.
What the test showed
SERT-III carried sensors to measure one of the key unknowns: would vaporized zinc coat the spacecraft's solar panels or optics? The answer, according to Muon's press release, was better than worst-case predictions. Thermoelectric quartz-crystal microbalance sensors recorded zinc deposition well below the most conservative pre-mission models, validating the plume behavior simulations Muon had run on the ground. The propellant feed and vaporization system matched ground-test data throughout.
The Starlight zinc-propellant thruster firing in orbit, as captured by SERT-III's onboard camera. Illustration: Muon Space
What comes next
The current Starlight generation targets small and mid-size spacecraft. Muon says it handles orbit raising, station-keeping, and end-of-life deorbit — the three maneuvers most commercial satellites need most. The company plans to fit Starlight onto customer satellites before the end of 2026. A larger Gen-2 version aimed at bigger spacecraft is scheduled for its first on-orbit test in Q1 2027, with a customer mission to follow later that year.
Muon built and launched SERT-III in under a year, which itself signals a shift: the same vertical integration that kept the test schedule tight is what lets the company move from demo to commercial deployment so quickly. If Gen-1 performs in service the way it did on July 1, xenon's grip on satellite propulsion will loosen considerably.
