Recently, NASA announced its plan to move the SLS Moon rocket off from its launch pad and back to the Kennedy Space Center’s Vehicle Assembly Building for a necessary upgrade for nitrogen supply, which according to Space News has been postponed for the last two countdown rehearsals.
The agency said the reason for taking back the SLS to the Vehicle Assembly Building was “due to upgrades required at an off-site supplier of gaseous nitrogen used for the test.” With that in mind, the agency will also replace a faulty helium check valve and repair a minor hydrogen leak discovered in one of the “umbilical” fuel lines from the rocket’s mobile launch tower. The faulty helium check valve in the SLS’s upper stage and the hydrogen leak were detected shortly after starting to load liquid hydrogen into the rocket’s core stage during the April 14 attempt.
According to NASA, “During that time, the agency will also review schedules and options to demonstrate propellant loading operations ahead of launch.”
For now, there is no update on when the vehicle would return from Launch Complex 39B, but the agency stated there will be a brief update on April 18 on the progress they’ve made so far. Therefore, more information regarding the decision will be revealed during a press conference scheduled for April 18th.