With the arrival of SLS and Orion at Pad-B on March 18, engineers and technicians were busy making final preparations for Sunday\u2019s critical last design verification test: the Wet Dress Rehearsal, or WDR.<\/p>\n
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.<\/p>\n
At this time, NASA has not announced when they will try again to fuel the SLS.<\/p>\n
The WDR will validate the vehicle\u2019s readiness for flight as well as all elements of the new Mobile Launcher and pad propellant system upgrades for LC-39B\u2019s liquid hydrogen storage and disposal systems \u2014 a multi-year process undertaken by NASA\u2019s Exploration Ground Systems team.<\/p>\n<\/p>\n
Wet Dress Rehearsal<\/p>\n
The test marks a significant milestone as NASA works towards launching SLS on Artemis 1 and is the first (and last) time Launch Director Charlie Blackwell-Thompson and the launch team have to take an actual SLS through a full-duration countdown ending just before the start of the Core Stage engine ignition.<\/p>\n
The final part of the wet dress countdown will see the launch team pick up the terminal count at T-10 minutes with a plan to count to T-90 seconds and then hold for three minutes to verify the vehicle\u2019s hold capability constraints that exist after the T-6 minute mark in the countdown.<\/p>\n
Spaceflight news subscription (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n Overall, according to NASA personnel in across interviews with NASASpaceflight\u2019s Philip Sloss, the team plans two runs through the terminal count, with the first incorporating the three-minute verification hold at T-90 seconds before continuing down to T-33 seconds.<\/p>\n