Phase Four, the creator of the radio-frequency thruster (RFT) for satellite propulsion, announced today that two small satellites powered by its flagship Maxwell plasma propulsion engine launched into space Sunday aboard the SpaceX Falcon 9 rocket as part of the Transporter-1 rideshare. The launch, which includes multiple commercial customers, also marks the first in a series of 2021 deployments of Phase Four’s high-performance, low-cost Maxwell propulsion systems for satellite constellations that are supporting a rapid expansion of in-space mobility.

Maxwell plasma propulsion engines will power two smallsats that will execute Earth observation missions in low Earth orbit (LEO) over several years. The RFT-powered Maxwell propulsion system maneuvers satellites to optimal orbit and maintains their positions to acquire and measure precise Earth imagery data. Propulsion for small satellites in LEO makes them far more agile to minimize collisions and extends mission lifetime by multiple years, which is critical for commercial spacecraft missions.

The Maxwell engines are designed to allow in-space mobility over several years, significantly extending the life of LEO satellites in order to maximize ROI on each satellite in a constellation. Depending on orbit altitude and mass, Maxwell enables small satellites to remain in their optimal orbits for 3-5 years, far longer than without propulsion or with legacy propulsion options. Maxwell, at 19 centimeters x 13.5 cm x 19 cm (7.5 inches x 5 in. x 7.5 in.) and under 6 kilograms (13 pounds), is the lightest, most compact all-in-one mid-range power plasma propulsion system commercially available on the market.

“We developed the Maxwell plasma propulsion engine to provide small satellites with an optimal level of thrust and efficiency in a lightweight, space-saving design that hasn’t existed before,” said Beau Jarvis, Phase Four CEO. “As a result, we’re seeing pent up demand for compact, high-performing satellite propulsion systems that have put us on track to deliver several Maxwell units to customers launching satellites in each quarter of 2021 and into 2022.”

About Phase Four

Phase 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. Learn more at