NASA Burned a Rocket Engine for a Full Launch Duration. It Will Never Fly.
NASA test-fired RS-25 engine No. 10001 on Oct. 21 on the Fred Haise Test Stand at the agency's Stennis Space Center near Bay St. Louis, Mississippi. The developmental engine burned for almost eight-and-a-half minutes — 500 seconds, the same length of time RS-25 engines fire during a launch of NASA's SLS rocket.
That engine will not be used in flight; the hot fire instead gives NASA and its prime contractor L3Harris Technologies critical data aimed at improving engine performance and reliability. In flight, four RS-25 engines produce up to 2 million pounds of combined thrust to help launch the SLS rocket on each Artemis mission.
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Five hundred seconds on a test stand is one launch's worth of burn, and in flight four of these engines together push up to 2 million pounds of thrust — so this is a dress rehearsal for the real thing, not a gentle warm-up.
Improving performance and reliability is a promise just about any hot fire can make on the day. The scorecard for a developmental engine isn't the burn itself; it's whatever changes show up in the next engine off the stand.