SLS still has helium leaks. Helium leaks have been a problem since the Space Shuttle days. It is so cold that it is hard to work with. The picture is of the SLS rolling back to the Vehicle Assembly Building in 2022. Rolling back to the bay for work will look the same in 2026.

– The ICPS helium bottles are used to purge the engines, as well as for LH2 and LOX tank pressurization. The systems did work correctly during WDR1 and WDR2.

– Last evening, the team was unable to get helium flow through the vehicle. This occurred during a routine operation to repressurize the system.

– We observed a similar failure signature on Artemis I.

– The Artemis II vehicle is in a safe configuration, using ground ECS purge for the engines versus the onboard helium supply.

– Potential faults could include the final filter between the ground and flight vehicle, located on the umbilical, though this seems least likely based on the failure signature. It could also be a failed QD umbilical interface, where similar issues have been observed. It could also be a failed check valve onboard the vehicle, which would be consistent with Artemis I, though corrective actions were taken to minimize reoccurrence on Artemis II.

Regardless of the potential fault, accessing and remediating any of these issues can only be performed in the VAB.