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Phase Four Wins U.S. Space Force Contract at SpaceWERX Pitch Day

By Doug Messier
Parabolic Arc
August 28, 2021
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EL SEGUNDO, Calif. (Phase Four PR) — Phase Four, the creator of the radio-frequency thruster for satellite propulsion, announced today that it has secured a contract with the U.S. Space Force at the SpaceWERX Pitch Day held on August 18th, 2021 for the company’s propellant-agnostic Maxwell engine. Under the contract, Maxwell will utilize ASCENT, a green propellant developed by the U.S. Air Force Research Laboratory, to enable multi-mode propulsion capability, which combines the high thrust capabilities of chemical propulsion and the high efficiency capabilities of electric propulsion.

“Space is rapidly becoming congested and contested,” said Phase Four CEO, Beau Jarvis.  “The U.S. Space Force and commercial satellite operators must increase the maneuverability of their spacecraft to operate safely and minimize on orbit risks.”

The hallmark of Phase Four’s versatile RF Thruster technology is its highly flexible architecture that allows it to easily operate on noble gases, the traditional propellants for electric propulsion, and on new alternative propellants ranging from solid iodine to liquid water to liquid rocket propellants. To date, multi-mode capability, operating chemical and electric propulsion from the same liquid rocket propellant, has not been possible with existing Cold War-era electric propulsion systems used on legacy satellites.

Together with the Air Force and Space Force, Phase Four will demonstrate operation of its radio-frequency thruster on ASCENT green propellant, paving the way for significantly enhanced maneuvering capabilities for future space vehicles via multiple modes of propulsion, akin to gears on a car:

  • “Low gear” chemical propulsion mode – high thrust, low efficiency chemical thruster for maneuvers such as rapid response orbit changes and collision avoidance 
  • “High gear” electric propulsion mode – lower thrust but high efficiency electric thruster for high delta-v orbit transfers and long duration station-keeping and phasing

Phase Four’s project received several letters of support from industry and government agencies that anticipate multi-mode propulsion engines will lead to more responsive and maneuverable space vehicles and create new opportunities for commercial and defense satellite operators.

Phase Four is also working with other government customers to further adapt Maxwell engines to operate on low cost solid propellant that can be stored without high pressure and can be delivered pre-fueled; ready for rapid integration to a satellite and launch without requiring expensive ground servicing operations. The company has also been scaling up its production capabilities to deliver higher quantities of Maxwell engines to small satellite manufacturers in industry-best lead times of 3-4 months.

“We’re looking forward to being at the forefront of new in-space propulsion capabilities with development of multimode propulsion with ASCENT,” said Jason Wallace, VP of Advanced Development at Phase Four. “Although this development is critical to maintaining the United States’ propulsive superiority in space for defense applications, the dual-use nature of this multimode technology is clear. As industry seeks to expand beyond Low Earth Orbit and standard mission profiles, we are seeing a growing industry need for propulsion that can adapt to the various stages of  commercial missions, from rapid deployment, to long-term station keeping, to collision avoidance and to deorbiting. This SpaceWERX contract is foundational to addressing both defense and commercial needs for multimode propulsion.”

About Phase FourPhase Four is a disruptive provider of simple electric propulsion (EP) solutions for small satellites. The company was founded in 2015 to address the demands of next-generation 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