Artemis II made the trip from Launch Complex 39B to the VAB today. The approximately 4-mile trek aboard Crawler-Transporter 2 began at around 9 AM ET and lasted until around 8 PM, when it arrived inside Bay 3 for repairs and battery updates.

Now back in the VAB, teams will immediately install platforms to access the helium flow hardware and will also take advantage of the downtime to replace batteries in the flight termination system and upper stage.

Helium Issues

The rollback was triggered by an issue with the flow of helium to the SLS rocket’s Interim Cryogenic Propulsion Stage that was observed overnight on February 21st, less than two days after NASA engineers and technicians had successfully completed its second wet dress rehearsal. That February 19 WDR had gone well enough that NASA was gearing up for a March 6th launch attempt before the helium issue surfaced.

Helium pressurization of the propellant tanks on the ICPS makes flow interruption a critical concern. Engineers are reviewing several potential causes, including problems at the interface between ground and rocket helium lines, a valve in the upper stage, or a filter between ground and flight hardware. NASA has also noted that Artemis I experienced a similar helium-related pressurization issue that required troubleshooting before its 2022 launch.

Next Launch Window

The next available launch opportunity opens April 1, though NASA has cautioned that hitting that window depends on how quickly engineers can diagnose and repair the issue.

The four Artemis II crew members — Commander Reid Wiseman, Pilot Victor Glover, Mission Specialist Christina Koch, and Canadian Space Agency astronaut Jeremy Hansen — were released from pre-launch quarantine on the evening of February 21st.