NASA’s Space Launch System moon rocket relied on advanced guidance algorithms, powerful cryogenic engines, and millions of lines of software code to get it off the ground for the first time Wednesday. But “there are also times when you’ve just got to put a wrench on a nut,” NASA’s Artemis ground systems program manager said. That’s what NASA did in final hours of the Artemis 1 mission’s countdown late Tuesday night, when the launch team called upon a “red crew” of two technicians and a safety engineer to tighten nuts around a leaky hydrogen valve.