December 23, 2020
NASA partially completed the Green Run Wet Dress Rehearsal (WDR) test of the Space Launch System (SLS) Core Stage on the second attempt in the B-2 Test Stand at the Stennis Space Center. The test was again conducted in secrecy on 20 December, and the test team was able to fill the rocket stage with its liquid oxygen (LOX) and liquid hydrogen (LH2) propellants for the first time ever; however, a crucial, 10-minute long terminal countdown was aborted inside of the 5 minute mark when a valve failed to close within pre-set time limits.
In a statement, NASA said that despite the early end to the test the issue doesn’t appear to be with the vehicle; after draining the stage, the agency’s SLS Program and Core Stage prime contractor Boeing are now reviewing data from the test and inspecting the stage after its first propellant loading cycle while they deliberate what to do next. The 8-minute long Hot-Fire test was expected about two weeks after a fully completed WDR,
SLS, Stennis working on colder LOX for next Green Run WDR attempt
December 11, 2020
Space Launch System (SLS) Core Stage Green Run team members are working on new procedures to supply liquid oxygen (LOX) to the vehicle at lower temperatures in the next Wet Dress Rehearsal (WDR) attempt. The first attempt on December 7 at the Stennis Space Center in Mississippi was scrubbed because the temperature of the LOX was a few degrees higher than design requirements as it entered the vehicle; NASA did not want to continue loading with the temperature out of limits.
The problem is not with the Core Stage itself; engineers with the SLS Program, Core Stage prime contractor Boeing, and NASA Stennis are looking at ways to reduce the temperature of the cryogenic liquid before it reaches the stage from barges docked next to the B-2 Test Stand. In the meantime, the test team is recycling the stage and other equipment to be ready to start a new Wet Dress Rehearsal attempt no earlier than the week of