Green Run Update: Engineers Repair Valve for Mid-March Hot Fire 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 eight minute duration hot fire test, Saturday, Jan. 16, 2021, at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. The four RS-25 engines fired for a little more than one minute. The hot fire test is the final stage of the Green Run test series, a comprehensive assessment of the Space Launch System’s core stage prior to launching the Artemis I mission to the Moon. (Credit: NASA/Robert Markowitz)

BAY ST. LOUIS, Miss. (NASA PR) — Engineers have successfully repaired a liquid oxygen valve on the Space Launch System rocket’s core stage with subsequent checks confirming the valve to be operating properly. The team plans to power up the core stage for remaining functional checks later this week before moving forward with final preparations for a hot fire test in mid-March at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. NASA anticipates setting a target date for the hot fire next week.

Last week during checkouts for the second hot fire test, data indicated the valve (a type of valve called a pre-valve) was not working properly. The valve is part of the core stage’s main propulsion system and is opened at the beginning of the test and closed if necessary to stop the flow of liquid oxygen from the core stage propellant tank to the respective RS-25 engine during the hot fire.

While the valve was repaired over the weekend, the team continued to prepare the core stage, its four RS-25 engines, and the B-2 test stand for the second hot fire at Stennis. This hot fire test will be the last test before the Artemis I core stage is shipped to the agency’s Kennedy Space Center for assembly and integration with the rest of the rocket’s major elements and the Orion spacecraft.

Please check back at this blog for an update on the date NASA is targeting for the second Green Run hot fire. For more information about SLS Green Run, visit