DENVER — NASA called off the first attempt to fuel its Space Launch System rocket and go through a practice countdown April 3, citing a problem with the rocket’s mobile launcher.
NASA announced shortly before 12 p.m. Eastern that it was scrubbing its wet dress rehearsal (WDR) for the SLS before crews started loading any liquid hydrogen and liquid oxygen propellant into the vehicle. The agency said fans in the mobile launch platform, required to create positive pressure in enclosed areas of the platform to avoid a buildup of hazardous gases, were not working.
The agency said in a brief blog post that the WDR could be rescheduled for as soon as April 4, pending reviews planned later in the day. That schedule will depend on the status of key systems, as well as availability of the range at the Kennedy Space Center and commodities needed for the test.
Even before the fan problem NASA was running behind schedule with the test, where the core and upper stages of the SLS are filled with propellants and go through a countdown that stops at approximately T-10 seconds. Severe thunderstorms April 2 delayed WDR activities at Launch Complex 39B, including several lightning strikes on protective towers at the pad.
NASA started WDR activities April 3 about one hour behind schedule, according to tweets posted by Jeremy Parsons, deputy manager of the Exploration Ground Systems program at KSC. Tweets and blog posts were the primary means NASA used to provide updates about the test after claiming that export control restrictions prevented it from providing audio from the launch control center or any other commentary.
The countdown went into an unplanned hold shortly after 8 a.m. Eastern April 3 to “sync pad operations” with the launch control center, Parsons tweeted. He later said that crews had confirmed positive pressure on the mobile launcher and, more than two hours after the hold started, NASA announced the countdown resumed, only to report a problem with the fans a short time later.
The WDR is the final major test before the inaugural launch of the SLS on the uncrewed Artemis-1 mission. NASA officials said at a March 29 briefing that, if the test goes well, the agency could be ready in about a week to set a launch date for the mission, likely no earlier than June.
The WDR, while intended to simulate a countdown, offers greater flexibility to correct problems than what crews would have during an actual countdown. “We are fortunate to have this flexibility during today’s test, but would operate differently on launch day,” Parsons tweeted shortly before the test was scrubbed for the day.