With the arrival of SLS and Orion at Pad-B on March 18, engineers and technicians were busy making final preparations for Sunday’s critical last design verification test: the Wet Dress Rehearsal, or WDR.
The test was scrubbed on April 3 before fueling due to an inability to provide positive pressure to the enclosed areas within Mobile Launcher -1 (ML-1) and was rescheduled for April 4 and then scrubbed that day at T-31 minutes 36 seconds due to a stuck gaseous hydrogen vent valve o the 18 meter (160 ft) level of ML-1.
At this time, NASA has not announced when they will try again to fuel the SLS.
The WDR will validate the vehicle’s readiness for flight as well as all elements of the new Mobile Launcher and pad propellant system upgrades for LC-39B’s liquid hydrogen storage and disposal systems — a multi-year process undertaken by NASA’s Exploration Ground Systems team.