The launch team had trouble getting one of the four RS-25 engines to the proper temperature for liftoff, which led to NASA postponing the launch of Artemis I, NASA said at the beginning of the press briefing on Monday.
“Once we got through the propellant loading on the rocket, both on core stage and the upper stage, they started the engine bleed,” said Artemis mission manager Mike Sarafin. “We talked in our flight readiness review about the engine bleed, we knew that that was a risk heading into this launch campaign and it would be the first time demonstrating that successfully.”
The launch was postponed this morning when the launch team discovered an issue with an engine bleed in engine #3. Before the launch, super cold liquid hydrogen is cycled through the engine to get it ready for launch. Three of the four engines were performing as expected, but engine #3 experienced an issue.
“We did encounter an issue chilling down engine #3. We need the engine to be at the cryogenically cool temperature such that when it starts, it’s not shocked with all the cold fuel that flows through it. So we needed a little extra time to assess that,” Sarafin explained.
“When the team started working through that, they also saw an issue with the vent valve at the inner tank,” he added.
“So the combination of not being able to get the engine #3 chill down and then the vent valve issue that they saw at the inner tank really caused us to pause today and we felt like a little more time,” he noted.