NASA has completed a critical repair of its next-generation Space Launch System (SLS) rocket. On Friday, engineers replaced the leaky seal that forced the agency to scrub its most recent attempt to launch Artemis 1. On September 3rd, a fitting on one of the fuel lines to the SLS began leaking hydrogen. Ground crew at Kennedy Space Center tried to troubleshoot the problem three times, only for the leak to persist and force NASA to call off the launch attempt. On Friday, engineers also replaced the seal on a 4-inch hydrogen “bleed line” that was responsible for a smaller leak during an earlier August 29th launch attempt.

With the new gaskets in place, NASA plans to conduct a fueling test to verify they’re working as intended. The dry run will see engineers attempt to load the SLS with all 736,000 gallons of liquid hydrogen and oxygen it would need during a regular flight. NASA hopes to successfully complete that test as early as September 17th. “This demonstration will allow engineers to check the new seals under cryogenic, or supercold, conditions as expected on launch day and before proceeding to the next launch attempt,” the agency said.

On Thursday, NASA announced it was targeting September 23rd for another go at putting Artemis 1 into space, with September 27th as a backup. Whether it can make those dates will depend on next week’s fueling test and a decision from the US Space Force. Flight regulations require that NASA test the battery of Artemis 1’s flight termination system every 20 days. That’s something it can only do within the Kennedy Space Center’s Vehicle Assembly Building. The Space Force previously granted the agency an extension on the 20-day deadline. NASA has now asked for another waiver.