NASA - The National Aeronautics and Space Administration

02/26/2021 | News release | Distributed by Public on 02/26/2021 09:23

Green Run Update: NASA Inspecting Valve, Continuing Hot Fire Preparations

NASA and Space Launch System (SLS) core stage prime contractor Boeing are thoroughly examining a liquid oxygen valve inside the stage's engine section in order to identify repairs needed before a second hot fire with the Artemis I stage.

During preparations for the second hot fire, data indicated the valve was not opening correctly. Technicians installed platforms that allow engineers to access the valve inside the core stage engine section while the stage remains in the B-2 stand at NASA's Stennis Space Center near Bay St. Louis, Mississippi. After completion of troubleshooting, which will continue over the weekend, NASA will be in a better position to identify a potential date for the second hot fire test.

This valve, called a pre-valve, must be fully operational during hot fire testing. The valve is part of the core stage main propulsion system, and it helps deliver liquid oxygen propellant flowing from the liquid oxygen tank to an RS-25 engine. For the first hot fire on Jan. 16, all four liquid oxygen pre-valves performed as expected as did all four liquid hydrogen pre-valves.

The Green Run is a comprehensive series of tests for the SLS core stage before it launches the Artemis missions to the Moon, and the hot fire is the final and most intensive test. The Green Run tests have provided invaluable information on how the new rocket stage operates before it is used to launch the Artemis I mission.

Check back at this blog for an update on actions needed to resolve the issue, as well as the schedule for the hot fire test. For more information about SLS Green Run, visit