The launch crew fixed a leaking hydrogen seal and adopted a milder hydrogen-loading procedure to resolve the issue. Hydrogen is an exceptionally effective rocket propellant, but its ultra-cold temperature and the minuscule size of its molecules make it prone to leaks. The hydrogen supplies the SLS rocket’s four core-stage engines and its single upper-stage engine.
“Artemis I was a test flight, and we learned a lot during that campaign getting to launch,” said Charlie Blackwell-Thompson, NASA’s Artemis II launch director. “The lessons we gained about how to load this vehicle — how to load LOX (liquid oxygen) and how to load hydrogen — have all been incorporated into the procedures we plan to use for Artemis II.”
NASA is reluctant to announce a firm launch date until after the dress rehearsal, but agency officials say a February liftoff is still possible.
“We’ve kept to the schedule fairly well up to rollout today,” Isaacman said. “We have no plans to announce a concrete launch date until after the wet dress. But that’s our initial window, and if things continue to track, I know the teams and crew are ready and we’ll take it.”
“The wet dress drives the launch,” Blackwell-Thompson said. “If the wet dress proceeds without major problems, and everything goes as planned, there are likely opportunities in February that could be attainable.”
A constraint that complicated NASA’s Artemis I launch campaign is no longer a major issue for Artemis II. During Artemis I, NASA rolled the rocket back to the Vehicle Assembly Building (VAB) after the wet dress rehearsal to finish installing and testing the flight termination system — a set of pyrotechnic charges meant to destroy the rocket if it veers off course and threatens populated areas after liftoff.
The US Space Force’s Eastern Range, which oversees public safety for launches from Florida’s Space Coast, requires the flight termination system to be retested every 28 to 35 days — a timer that began last week before rollout. On Artemis I, technicians couldn’t reach the rocket sections they needed to perform the retest at the pad. NASA has since added structural arms so ground crews can access higher portions of the rocket for the retest without returning it to the hangar.
With that capability, Artemis II could stay at the pad for February and March launch opportunities before officials must return it to the VAB to replace the flight termination system’s batteries, which remain inaccessible at the pad.
