The wet-dress rehearsal – a series of key tests designed to show that the huge Artemis 1 Space Launch System (SLS) rocket, the Orion spacecraft and related ground infrastructure are ready to launch – began April 1 at Pad 39B in NASA Kennedy Space Center (KSC) in Florida. Things were supposed to end about 48 hours later, with the loading of liquid hydrogen and liquid oxygen propellants into the SLS and the execution of several simulated launch measurements. Artemis 1 crew members encountered many problems that delayed these steps, however, and eventually resigned to host the private Ax-1 astronaut mission, which was launched over a SpaceX Falcon 9 rocket on April 8 from its Pad 39A. KSC. The wet dress returned on April 12, in modified form: After discovering a defective valve at the bottom of the launch of the cell phone that supports the Artemis 1 stack, the team decided to power only the basic SLS stage, not the upper stage. The technicians started supplying the main stage on April 14 as planned, but stopped after noticing that liquid hydrogen was leaking from one of the “umbilical” lines extending from the mobile launcher to the SLS. Following the end of this catering effort – the third wet dress campaign after failed attempts on April 3 and 4 – members of the Artemis 1 team took some time to analyze their data and choices. They initially left the door open to repeat the wet dress next week, with another attempt perhaps going up as early as Thursday (April 21st). But this is no longer on the table. The team decided to drop the Artemis 1 stack off the Pad 39B and return to the KSC Cave Vehicle Assembly Building to replace the defective valve and deal with the leaking umbilical boiler. “During this period, the agency will also review schedules and options to demonstrate propulsion loading functions prior to launch,” NASA officials wrote in a statement Saturday (April 16th). The decision, or at least its timetable, was driven to some degree by external factors, NASA officials said, citing upgrades required “to a nitrogen gas supplier used for off-site testing.” We will learn more about the decision and the plans that will follow soon. NASA will hold an Artemis 1 press conference on Monday (April 18) at 3 p.m. EDT (1700 GMT). You can watch it live on Space.com. Mike Wall is the author of “Out there“(Grand Central Publishing, 2018, illustrated by Karl Tate), a book about the search for extraterrestrial life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or up Facebook.
