Space shuttle engine test advances repurposing program for manned deep space missions


NASA and Aerojet Rocketdyne have hot-fired an RS-25 engine in a test that shows further progress for their program to repurpose the engines, previously used on the space shuttles, for use in the agency’s latest Space Launch System. 

NASA plans to use the Space Launch System (SLS) for the first time in 2019 to power the launch of Exploration Mission-1 (EM-1). This mission will test the SLS and Orion spacecraft for EM-2, a mission which will send astronauts to an area near the moon and which is planned for 2023.

EM-2 will be the first manned mission beyond low-Earth orbit in nearly 50 years.

The RS-25 engine was used to power all 135 Space Shuttle missions between 1981 and 2011. Since 2015, NASA and Aerojet Rocketdyne have been repurposing and modifying 16 RS-25 engines leftover for use in the SLS.

Expendable versions of the RS-25 engine will be used in clusters of four for the launch vehicle’s core stage. While on the shuttle, the engines ran at 491,000 lb vacuum thrust. The Rs-25 engine’s power level is being increased for SLS to 512,000 lb vacuum thrust to augment the vehicle’s heavy lift capability. 

Controller and shock absorber

Testing the 3D-printed pogo accumulator on the RS-25 engine

The 365-second test at NASA’s Stennis Space Center, Mississippi, qualified the controller for the third of the four RS-25 engines. The new controller weighs less and has more processing power than previous versions, making the engine more responsive to vehicle commands.

Also on the test engine was an additively manufactured component designed to dampen engine vibrations that could create stability issues during flight. 

The pogo accumulator assembly, the engine’s largest additively manufactured component to date, has now performed successfully on two successive RS-25 hot fire tests. The first test was performed in December 2017.

Dan Adamski, RS-25 program director at Aerojet Rocketdyne said, “We ended 2017 with a successful engine test in December and have now maintained that momentum into 2018.

“Future testing this year will continue to add to the program’s inventory of flight controllers and will bring additional development hardware into the test program to demonstrate design, manufacturing and affordability improvements. Our pogo accumulator assembly is just one of the first of these efforts to be hot-fire tested.”

Nozzle insulation is also being added to the RS-25 engines for protection and prevention of metal overheating during launch and flight. Other checks before the engines fly again will include torque testing, leak checks and an avionics software check.

Future versions of the RS-25 will be simpler in design and will be made using modern processes such as additive manufacturing, Aerojet Rocketdyne said.

January 22, 2018

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Ben has worked as a journalist and editor, covering technology, engineering and industry for the last 20 years. Initially writing about subjects from nuclear submarines to autonomous cars to future design and manufacturing technologies, he was editor of a leading UK-based engineering magazine before becoming editor of Aerospace Testing in 2017.

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