Aerojet has wrapped up development testing of a monopropellant hydrazine thruster designed with NASA human spaceflight missions in mind.

Work on the MR-104H — an updated version of the an Aerojet thruster flying on the Voyager 1 probe NASA launched in 1977 — got started under Constellation, NASA’s defunct effort to return astronauts to the Moon around 2020.

Aerojet said in an April 26 press release that environmental and hot-fire performance testing of the MR-104H was recently completed in Redmond, Wash. Working with Boeing Exploration Launch Systems and NASA Marshall Space Flight Center, Aerojet conducted a series of tests over the past three years that the company says advanced the thruster’s demonstrated capabilities for future space vehicles, including verifying that the engine is capable of generating up to 200 pounds of thrust.

“We have worked with our partners to mature the thruster from its flight-proven spacecraft application toward human-rated application,” Scott Miller, executive director of Aerojet Space and Launch Systems, said in the release. “We are looking forward to this technology supporting a new generation of U.S. space exploration.”