Phase Four won a U.S. Air Force AFWERX contract in 2021 to test iodine propellant in its electric thrusters.

Phase Four won a Defense Advanced Research Projects Agency contract to demonstrate the California startup’s radio frequency thruster technology with a new propellant.

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Debra Werner is a correspondent for SpaceNews based in San Francisco. Debra earned a bachelor’s degree in communications from the University of California, Berkeley, and a master’s degree in Journalism from Northwestern University. She is a recipient...