Phase Four Awarded Novel Thruster Prototype Development Contract by DARPA

A recent successful firing of the Phase Four RF Thruster using sublimated iodine as propellant. (Credit: Phase Four)

EL SEGUNDO, Calif., Feb. 16, 2022 (Phase Four PR) — Phase Four, the creator of the radio-frequency thruster (RF Thruster) for satellite propulsion, announced today that it finalized a contract with the Defense Advanced Research Projects Agency (DARPA) to adapt the RF Thruster to operate on novel, low cost propellants. The effort includes the development of a prototype engine and vacuum chamber testing. The results of the prototyping effort will demonstrate the proof of concept of a novel plasma propulsion system for various mission applications.

“One of the unique aspects of our core technology, the RF Thruster, is propellant agnosticism,” said Phase Four VP of Advanced Development, Jason Wallace. “Unlike legacy electric propulsion systems that rapidly degrade when exposed to non-traditional propellants, Phase Four’s RF Thruster is ideally suited to operate with novel propellants. We look forward to working with DARPA to further prove out this capability for future defense and commercial missions and constellations.”

Phase Four’s Maxwell Block 1 engine gained flight heritage in 2021 and is currently operating on several commercial small satellites. The company recently introduced its second generation RF Thruster, which revealed significant performance improvements over the first generation thruster. Phase Four has demonstrated the ability of its RF Thruster to operate on a variety of nontraditional propellants, including water, oxygen-nitrogen mixtures and isopropyl alcohol. The company is currently performing thrust measurements with its Maxwell engine adapted to operate on iodine on an Air Force Research Laboratory (AFRL) sponsored program, and recently won a Space Force Pitch Day award to test on green propellant.

A visualization of the Phase Four Radio-Frequency Thruster’s propellant agnosticism from images captured during recent test campaigns with both traditional and advanced propellants used to produce plasma resulting in thrust for satellites in space. (Credit: Phase Four)

“Phase Four continues to demonstrate the versatility of the RF Thruster,” said Phase Four CEO, Beau Jarvis. “Bringing low cost, high performance novel propellants to market through our Maxwell engine is an important step to transforming the satellite industry. Not only do these novel propellants support the industry shift towards lower cost, mass manufactured satellites, they provide unique propulsive capabilities to expand mission possibilities for our customers.”

About Phase Four

Phase Four is a disruptive provider of next generation electric propulsion (EP) solutions for small satellites. The company was founded in 2015 to address the demands of the rapid proliferation of satellite constellations and to accelerate the advancement of its radio-frequency thruster (RFT). The Phase Four RFT represents a revolutionary new architecture that realizes lower cost, mass-manufacturability, miniaturized power electronics, and propellant agnosticism over incumbent technologies, without compromising performance. In 2021 Phase Four’s Maxwell turn-key propulsion system achieved flight heritage and is now being regularly utilized by small satellite operators. Learn more at