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NASA knows what caused the early engine shutdown of its 1st SLS moon rocket during major test

The core stage for the first flight of NASA’s Space Launch System rocket is seen in the B-2 Test Stand during a scheduled 8-minute hot-fire test on Jan. 16, 2021, at NASA’s Stennis Space Center in Mississippi. The four RS-25 engines fired for a little more than one minute.
The core stage for the first flight of NASA’s Space Launch System rocket is seen in the B-2 Test Stand during a scheduled 8-minute hot-fire test on Jan. 16, 2021, at NASA’s Stennis Space Center in Mississippi. The four RS-25 engines fired for a little more than one minute. (Image credit: NASA/Robert Markowitz)

The core stage of NASA's giant Space Launch System (SLS) moon rocket is in good shape despite its early shutdown during a crucial test this past weekend, agency officials said.

The four-engine SLS core blazed to life on Saturday (Jan. 16) during a hot-fire test at NASA's Stennis Space Center in Mississippi. The engines were supposed to burn for 485 seconds — the duration they would fire during a moon mission — but shut down after just 67 seconds.

After analyzing data from the test, NASA has determined that the problem was not with the engines or other hardware, which remain "in excellent condition," agency officials wrote in an update today (Jan. 19). Rather, the shutdown "was triggered by test parameters that were intentionally conservative to ensure the safety of the core stage during the test."

Video: How NASA's SLS megarocket engine test works

Those parameters concerned engine hydraulics — specifically, the system designed to gimbal, or pivot, each engine during flight. On Saturday, the preset parameters for Engine 2's system were exceeded, and the core stage's flight computers ended the test automatically, NASA officials wrote in the update. If this same issue crops up during an actual flight, the SLS will be able to fly through it, they added.

The core also generated a "major component failure" (MCF) reading during Saturday's test. That reading, which occurred about 1.5 seconds after the engines started, did not contribute to the shutdown and may be an issue with the instrumentation for Engine 4, NASA officials said.

The SLS team will continue to investigate the MCF reading. Team members will also delve deeper into reports of a bright flash observed near the engines around the time of shutdown, though sensor data and visual inspection of the area have not turned up anything anomalous thus far.

SLS is vital to NASA's Artemis program, which aims to land two astronauts near the lunar south pole in 2024 and establish a permanent human presence on and around the moon by the end of the decade. The core that was tested on Saturday will launch the Artemis 1 mission, an uncrewed test flight of the agency's Orion capsule around the moon.

Artemis 1 is currently scheduled to lift off in late 2021 from NASA's Kennedy Space Center in Florida. It's not yet clear how Saturday's events affect that proposed timeline; the SLS team is still weighing whether or not a second hot-fire test at Stennis is needed, NASA officials wrote in the update.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook. 

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Mike Wall
SPACE.COM SENIOR SPACE WRITER — Michael has been writing for Space.com since 2010. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.