Press Release

Phase Four Sees Fourth Maxwell Engine launch with Capella Space SAR Satellite on SpaceX Dedicated Rideshare Launch

By SpaceRef Editor
July 1, 2021
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Phase Four, the creator of the radio-frequency thruster for satellite propulsion, announced today that a Maxwell engine was launched onboard a Capella Space SAR satellite on the SpaceX Transporter-2 dedicated rideshare launch on June 30th.  This marks the company’s fourth engine sent to space with Capella since January 24th of 2021.

“Over the past 2 years we’ve developed a strong working relationship with Phase Four,” said Capella Space CTO, Christian Lenz.  “The Maxwell systems in our satellites have been functioning nominally in the lab and in orbit, and Phase Four has provided great customer service all along the way.  This has given us confidence to order additional engines.  We look forward to continuing our partnership and look forward to future advances in Phase Four’s technology.”

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. Maxwell, now referred to as Maxwell Block 1, 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  turn-key plasma propulsion system in its class.  Phase Four recently introduced two new versions of Maxwell – Maxwell Block 2 and Block 3 – to address a larger segment of the satellite industry.

“We have worked closely with Capella to develop, enhance, produce, launch and operate our first Maxwell Block 1 propulsion systems,” said Phase Four CTO, Umair Siddiqui. “Thanks to this partnership we have flight data that confirms successful on-orbit operations of the first electrodeless RF thruster to ever fly in space. We’re honored to continue working with the Capella Space team, and are looking forward to delivering additional, more advanced Maxwell units in the near future.”

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

About Capella Space

Capella Space is an information services company that provides on-demand 50cm high-resolution synthetic aperture radar (SAR) Earth observation imagery. Through a constellation of small satellites, Capella provides easy access to frequent, timely and flexible information affecting dozens of industries worldwide. Capella’s high-resolution SAR satellites are matched with unparalleled infrastructure to deliver reliable global insights that sharpen our understanding of the changing world – improving decisions about commerce, conservation and security on Earth. Learn more at

SpaceRef staff editor.