The legendary rocket engines of the Space Shuttle era have been given a chance to return to space flight. NASA’s Space Launch System (SLS), which is set to return humans to the Moon as part of the Artemis II mission, has successfully completed critical testing with four RS-25 engines, three of which are true veterans of spaceflight.
The NASA team managed to establish reliable communication between the main stage of the super-heavy SLS rocket and its boosters during engineering tests. This step is crucial ahead of the first manned flight to the Moon in more than 50 years. The peculiarity lies in the very “heart” of the system: three of the four RS-25 engines for Artemis II were previously used in the Space Shuttle program (1981–2011), completing a total of 22 space missions. Only one engine is new.
What the engines “revealed”
“I learned during the Space Shuttle program to listen to the engines,” says Bill Muddle, RS-25 engineer. “The engines talk to you, and you have to listen and understand what they are telling you to ensure they operate properly. Based on the PSET tests, the engines all indicated they were healthy and ready for the pad.”
This week, Exploration Ground Systems teams completed the @NASAArtemis II core stage Program Specific Engineering Test. This test verified avionics boxes and their functions, main propulsion systems for the RS-25 engines, auxiliary power units, and more.
— NASA's Kennedy Space Center (@NASAKennedy) July 2, 2025
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Muddle emphasizes the enormous responsibility: the lives of the astronauts in the Orion capsule depend on the flawless operation of these engines during the critical 8.5 minutes of ascent and the reaching of the first cosmic velocity to enter Earth orbit.
Financial challenges and the future of SLS
SLS actively utilizes the legacy of the Shuttle program. In addition to the RS-25 engines manufactured by Aerojet Rocketdyne / L3Harris, there are also solid-fuel boosters from Northrop Grumman. However, budget overruns became a serious problem. The cost of developing the SLS exceeded plans by $6 billion.
The future of the giant lunar rocket is not entirely certain. The proposed budget calls for a gradual phase-out of the SLS and Orion capsule in favor of commercial alternatives. However, the Senate’s recent approval of a bill to allocate an additional $6 billion to the Artemis program could be a lifeline. These funds will potentially give SLS and its veteran engines a chance to prove their necessity in returning humanity to the Moon.
We previously reported on how Texas demanded that Space Shuttle Discovery be returned to them.
According to l3harris.com
