Enlarge / The SLS core stage at NASA's Stennis Space Center after firing up for the Green Run test on January 16, 2021. (credit: Trevor Mahlmann)
After completing a review of data collected from a hot fire test of its Space Launch System rocket in mid-December, NASA has decided it needs to test the large vehicle again. The all-up engine firing is scheduled to occur as early as the fourth week of February.
During the December 16 test firing, when NASA intended to run the rocket's four main engines for up to eight minutes, the test was aborted after just 67.2 seconds. NASA said the engine firing was stopped due to a stringent limit on hydraulic pressure in the thrust vector control mechanism used to gimbal, or steer, the engines.
In the days after the mid-December test firing, officials from NASA and Boeing were coy about whether they would need to test-fire the rocket a second time. While it would be useful to gain additional data, they said, there were concerns about putting the core stage, with its four space shuttle main engines and large liquid oxygen and hydrogen fuel tanks, through the stress of repeated tests. (The SLS rocket is expendable, so it is intended to be launched only a single time.)
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source https://arstechnica.com/?p=1738654