The Kennedy Space Center was a hive of activity on Wednesday when NASA launched its Artemis I rocket. The red crew played a key role in getting the mission back on track.

When they performed live repairs to a leak on a fueled rocket, the red crew members did something dangerous and risky. It was another day at the office for them, if the office reduced you to nothing more than a memory in an instant.

Mr. Annis said in an interview that they were very excited. I was ready to leave.

Human beings try to be as far away from a rocket as possible. A controlled chemical reaction lifts tons of material to space on a tower of fire. It's the worst day of the year because it's an explosion that destroys anything that gets too close.

The commentator on NASA's live video feed announced on Tuesday that real human beings were heading to the launchpad. They wanted to fix parts on the Space Launch System that were leaking hydrogen and were threatening to ground the rocket.

The red crew members and their minders drove up to the launch pad in white vehicles. Three characters wearing dark clothing ascended a part of the launch tower and started working.

Mr. Annis said that they were focused on what was happening up there. It's creaking, it's making noises, and it's pretty frightening.

The work was not done by rocket engineers. Mr. Nail said that something needed to be Torqued. bolts need to be tightened because the valves they controlled might have been leaking

Mike Bolger, the Exploration Ground Systems program manager at Kennedy Space Center, said at a post-launch news conference that there are times when advanced technology is needed.

The valves were tested by engineers in launch control. There was a leak. There was a restart of the loading of hydrogen.

The work of the red crew was not new. In response to a similar leak more than 50 years ago, a group played a part.

A NASA transcript from 1969 states that a team of technicians and a safety man were sent to the pad to tighten bolts around the valve. We will send hydrogen again through the system to make sure the leak has been fixed.

Neil, Buzz, and Michael Collins made it to the moon because of the repair.

The Artemis I mission rocket was on its way to the moon about five hours after the Red Team visited the launchpad. Mr. Cairns had worked on red crews for 37 years but had never gone to the launchpad in such a dangerous situation. Mr. Annis said he hadn't appreciated his contribution to the mission yet.

He said he couldn't believe it. It's crazy to me.

The experience of the three men shows how space exploration is a team sport, according to an astronauts who has served aboard the International Space Station.

She said that she thought you guys showed that. We couldn't have done this on our own.

Kenneth Chang made a report.