On Saturday morning, NASA scrubbed its second attempt to launch the Artemis I mission into lunar orbit. This time, the culprit was a liquid hydrogen leak that showed up while the team was loading the rocket's core stage. During a press conference later in the day, Jim Free, an associate administrator at NASA Headquarters, said we shouldn't expect to see a third attempt within this launch period, which culminates Tuesday.
According to the space agency, the leak occurred "while loading the propellant into the core stage of the Space Launch System rocket" and that "multiple troubleshooting efforts to address the area of the leak, by reseating a seal in the quick disconnect where liquid hydrogen is fed into the rocket, did not fix the issue."
This is the second time the Artemis I mission has been delayed. Liftoff attempt No. 1 was scheduled for Monday, but launch director Charlie Blackwell-Thompson had to call a scrub then as well, because of an unyielding problem with what's known as an engine bleed test. (This process is meant to allow the engines to chill to the right temperature by releasing a small amount of the fuel.)
"We were unable to get the engines within the thermal conditions required to commit to launch," Artemis mission manager Mike Sarafin said during a press conference Tuesday. "In combination with that, we also had a bent valve issue on the core stage, and it was at that point that the team decided to knock off the launch attempt for that day."
Inside the double delay
The team's troubleshooting efforts occurred over several hours, as the Artemis team zeroed in on sealing the leak, starting with two tries at what you might call "turning it off and on again." The supercold hydrogen fuel was halted in its tracks, the tank connector was warmed, then the fuel flow was resumed in hopes of sort of steam-sealing the leak. This wasn't working. Then, NASA redirected efforts to a new solution: pumping the tank with helium. Nope. The leak persisted.
"This particular quick disconnect did not have a problem of this magnitude on Monday," Sarafin said during Saturday's presser. "We did see a small leak, but we did not see one of this magnitude."
In other words, Monday's leak was manageable, Sarafin said. "This was not a manageable leak."
So, at approximately 11:17 a.m. ET, roughly three hours before Saturday's launch window was set to open, Blackwell-Thompson made the call to scrub Saturday's attempt.
Free said that either Monday or early Tuesday we'll know more about when Artemis I's next viable launch period will begin. However, he noted it could fall as far as the latter part of October. And Sarafin suggested that rolling the SLS off the pad and back into the Vehicle Assembly Building isn't out of the question.
"As part of this initial test flight, we're learning the vehicle. We're learning how to operate the vehicle, and we're learning all of the things required to get us to fly," Sarafin said. "We are still learning as we go to get this vehicle off safely, so our focus is on understanding the problem and developing solutions in terms of schedule, but also risk impacts."
Read more: NASA's Artemis I Moon Launch: What You Need to Know About the Mega Mission