NASA’s crawler-transporter 2, carrying NASA’s Artemis II SLS (Space Launch System) rocket with the Orion spacecraft.
NASA’s crawler-transporter 2, carrying NASA’s Artemis II SLS (Space Launch System) rocket with the Orion spacecraft, arrives Wednesday, Feb. 25, 2026, inside the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida to troubleshoot the flow of helium to the rocket’s upper stage. Once complete, the SLS rocket will roll back to Launch Complex 39B to prepare to launch four astronauts around the Moon and back for the Artemis II test flight.
Credit: NASA

With NASA’s Artemis II SLS (Space Launch System) rocket and Orion spacecraft in the Vehicle Assembly Building at the agency’s Kennedy Space Center in Florida, technicians have accessed the launch vehicle stage adapter to inspect components that prevented helium from flowing to the upper stage after a Feb. 21 wet dress rehearsal.

Engineers determined a seal in the quick disconnect, through which helium flows from the ground systems to the rocket, was obstructing the pathway. The team removed the quick disconnect, reassembled the system, and began validating the repairs to the upper stage by running a reduced flow rate of helium through the mechanism to ensure the issue was resolved. Engineers are assessing what allowed the seal to become dislodged to prevent the issue from recurring.

While the upper stage repair has been underway, technicians also have been working to refresh other systems on the rocket. They are activating a new set of flight termination system batteries ahead of end-to-end retesting of the system and also are replacing the flight batteries on the upper stage, core stage, and solid rocket boosters, and charging the Orion launch abort system batteries. Work to replace a seal on the core stage liquid oxygen line feed system began March 2. Once complete, teams will reassemble the oxygen tail service mast umbilical plate and perform various integrity tests to ensure the seal interface is tight.

Work on the rocket and spacecraft will continue in the coming weeks as NASA prepares for rolling the rocket out to the launch pad again later this month ahead of a potential launch in April.

NASA Repairs Upper Stage Helium Flow, Preps Continue Ahead of Rollout