US spacecraft company Portal Space Systems has conducted what it describes as a first-of-its-kind test for the commercial space industry, successfully operating a solar thermal propulsion (STP) system at full power and high temperatures inside a vacuum chamber. The demonstration validated key elements of the technology used in Supernova, the company’s spacecraft designed for long-duration missions and enhanced orbital maneuverability.
The test campaign took place at Portal’s facility in Bothell, Washington, and confirmed the performance of the company’s patented, 3D printed heat exchanger (HEX) thruster, called Flare. According to Portal, the thruster achieved the expected results under flight-like conditions and enables spacecraft to travel “from LEO to MEO in a few hours, MEO to GEO in under a day, and LEO to Cislunar space in just a few days,” using a single, storable, non-cryogenic propellant—ammonia.
“With maneuverability becoming a defining advantage in space operations, Supernova is built to give national security and commercial operators the ability to reposition, respond, and persist across orbits,” said Jeff Thornburg, CEO of Portal Space Systems. “This propulsion system unlocks mission tactics and timelines that traditional chemical or electric systems simply can’t support.”
STP Test Confirms Supernova’s Mobility
Solar thermal propulsion has been investigated by NASA and the U.S. Air Force since the 1960s but has largely remained at the research stage. Portal states it is the first commercial company to demonstrate the technology in a flight-representative environment, using additive manufacturing, advanced materials, and a new heat exchanger design to make STP suitable for operational missions.
Unlike conventional systems focused on maintaining orbital position, Supernova is designed for mobility, supporting transfers and extended presence across LEO, MEO, GEO, and Cislunar space. The propulsion system relies on a non-cryogenic propellant and operates without combustion, allowing for potential refueling and a projected operational life exceeding five years.
The test campaign included full-power operation of the Flare thruster in vacuum, verification of thrust and specific impulse predictions, and high-temperature performance validation of its 3D printed heat exchanger. Portal’s facility used high-power electric heating to simulate solar energy, and the company reports that the propulsion architecture has been validated for integration with future flight hardware.
Key Tests in 3D Printing Prove Successful
Beyond Portal Space Systems, other industry players are also advancing 3D printing for aerospace applications.
In September, Firehawk Aerospace, a manufacturer of advanced energetics systems for defense, successfully completed the first flight test of its AM GMLRS-class Firehawk Analog (GFA), a 3D printed hybrid rocket engine system. This demonstration highlights the company’s capability to produce hybrid propulsion systems additively, as part of its ongoing Phase III SBIR contract with the Army Applications Laboratory (AAL).
Elsewhere, New Frontier Aerospace (NFA), an equity-funded startup specializing in advanced rocket propulsion, successfully completed a series of hot fire tests for its Mjölnir rocket engine. The engine, produced using AM, features a full-flow staged combustion cycle, one of the most efficient designs for liquid rocket propulsion. This makes Mjölnir well-suited for reusable launch systems, hypersonic vehicles, and orbital transfer platforms.
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Image featured shows Solar Thermal Propulsion System Test for Multi-Orbit Spacecraft. Photo via Portal Space Systems
