Initial RS-25 Certification Campaign of 12 Hot-Fire Tests Complete

Aerojet Rocketdyne and NASA completed a certification test series yesterday for the new RS-25 production engines that will propel NASA’s Space Launch System (SLS) exploration rocket for Artemis missions, beginning with Artemis V. This test series ensures the new engines will perform with the same reliability and robustness of their predecessors.

“With the completion of this 12-test campaign, we have cleared a major milestone in our RS-25 production restart program,” said Eileen P. Drake, Aerojet Rocketdyne CEO and president. “The test series went very smoothly, raising our level of confidence that the new hardware designs and manufacturing processes will yield highly producible, reliable engines.”

The SLS core stage is powered by four Aerojet Rocketdyne RS-25 engines, each capable of generating more than 500,000 pounds of thrust. Like Artemis I, the next three SLS flights are using heritage Space Shuttle Main Engines that have been upgraded with modern flight controllers, while subsequent missions will have newly built RS-25 engines that have been redesigned for improved performance and lower costs, and feature simplified component designs that take advantage of 3D printing and other manufacturing advances. The RS-25 is the only high-performance, liquid hydrogen, staged combustion cycle engine operational worldwide.

The recently completed test series, which began Feb. 8 and wrapped up June 22 on the historic Fred Haise Test Stand at NASA’s Stennis Space Center, involved firings ranging in duration from 500 seconds—matching the nominal SLS flight profile—to 720 seconds. During the test series, the engine was tested across the full range of power level settings required for flight—from 80% to 111% rated power—and even some time at 113% rated power, to demonstrate operational safety margin.

The certification campaign also tested the engine’s redesigned nozzle, demonstrated engine gimballing at angles ranging from 1 to 6 degrees off center, and showcased the new optimized flexible fuel and oxidizer feed lines that result in more cost-effective hardware components. The longer-duration tests and gimbal demonstrations are relevant to certain flight scenarios and help expand the RS-25 performance database.

NASA and Aerojet Rocketdyne will begin a similar 12-test series on a different engine later this summer to complete the certification process. The newly manufactured engines are scheduled to begin delivery to NASA in 2024 and will make their debut on the Artemis V mission.