Rocket re-do: NASA will run SLS Green Run test again

Boeing, NASA targeting late February to repeat rocket test

The B-2 Test Stand at NASA’s Stennis Space Center near Bay St. Louis, Mississippi with the core stage for NASA’s Space Launch System (SLS) rocket. Credits: NASA (NASA 2021)

ORLANDO, Fla. – NASA announced Friday it will repeat the hot fire test of the Space Launch System core stage next month after the first attempt was halted well short of the desired eight-minute run.

The Space Launch System core stage was slated to fire its four engines on the test stand at NASA’s Stennis Space Center in Mississippi on Jan. 16 for eight minutes but barely fired for one minute. The hydraulic system for one engine exceeded safety parameters, NASA officials said, and flight computers shut everything down 67 seconds into the ignition.

NASA officials said they were first reviewing all the data before deciding if another Green Run test would need to happen before the hardware is brought down to Kennedy Space Center for launch. The core stage built by Boeing will be used on the Artemis-1 mission, sending the uncrewed Orion spacecraft around the moon and back.

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The Green Run test is the eighth and, hopefully, final test in a series needed to prepare the rocket for launch and really put the pedal to the metal testing its power and capabilities.

The SLS core stage booster contains the liquid hydrogen tank and liquid oxygen tank, along with four RS-25 engines as well as the computers that serve as the “brains” of the rocket.

In a statement, NASA said it could try again as early as the fourth week in February.

“While the first hot fire test marked a major milestone for the program with the firing of all four RS-25 engines together for the first time for about a minute, it ended earlier than planned,” NASA’s post read. “After evaluating data from the first hot fire and the prior seven Green Run tests, NASA and core stage lead contractor Boeing determined that a second, longer hot fire test should be conducted and would pose minimal risk to the Artemis I core stage while providing valuable data to help certify the core stage for flight.”

While a Green Run test normally runs eight minutes, the length required if the rocket were headed into space, NASA release said the agency is looking for at least four more minutes of data to verify it’s ready to fly. The agency does intend to fire all four engines for eight minutes if all goes well.

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NASA has attributed the automatic shutdown during the first Green Run test to the strict test limits meant to protect the core stage so it can be used on the first Artemis flight. Prior to the second go around, teams will be updating those conservative parameters.

NASA said the SLS team also replaced a faulty electrical harness but that did not contribute to the test ending early.

If all goes well during the second try, the core stage will undergo some refurbishment and then be transported via barge down to Florida.

The space agency is still targeting the first launch of SLS, known as Artemis-1, for later this year.