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, but with the countdown demonstration incomplete, SLS engineers and management will have to decide if and when to proceed to the stage firing.