February 22, 2026

— NASA's march to the moon has been delayed to April.

The space agency's plans to launch the Artemis II crew as soon as the first week of March have been postponed by at least a month due to their rocket needing to return to its assembly building. The decision to roll back the Space Launch System (SLS) came after a problem emerged with its upper stage.

"Data showed an interruption in helium flow in the SLS interim cryogenic propulsion stage [ICPS]," wrote Jared Isaacman, NASA Administrator, in a social media post on Saturday (Feb. 21). "This occurred during a routine operation to repressurize the system."

"This will take the March launch window out of consideration," said Isaacman.

Next month's opportunities ran from March 6 to March 11. The April window opens on April 1 and extends through April 6 before jumping to April 30. The dates are determined, in part, by the position and orientation of the moon in relation to Earth, given the mission's goal of flying by the far side of the moon while it is in daylight.

Teams at NASA's Kennedy Space Center in Florida are reviewing the exact time to begin the approximately 4.2-mile (6.8-km) rollback from Launch Pad 39B to the Vehicle Assembly Building (VAB), reversing the nearly 12-hour trip that the SLS took in January. An upgraded, Apollo-era crawler transporter will transport the SLS atop its mobile launcher at a max speed of 1 mile per hour (1.6 kp/h).

Artemis II live views. Click to enlarge video in new pop-up window. (NASA)

Fixing the flow

The helium flow issue was discovered after NASA had completed two practice launch countdowns, known as a "wet dress rehearsal" (WDR). The approximately 50-hour trial revealed hydrogen leaks during its first run, which were corrected for before conducting the second tanking test.

"The ICPS helium bottles are used to purge the engines, as well as for LH2 and LOX [liquid hydrogen and liquid oxygen] tank pressurization. The systems did work correctly during WDR1 and WDR2," wrote Isaacman.

Among the potential culprits could be the final filter on an umbilical connecting the SLS to the launch pad or a failed quick-disconnect umbilical interface, where similar issues have been seen before. A helium flow issue was also encountered in the lead up to the Artemis I launch in 2022.

"It could also be a failed check valve on the vehicle, which would be consistent with Artemis I, though corrective actions were taken to minimize reoccurrence on Artemis II," said Isaacman.

In all of these cases, the only way to access the area to troubleshoot and remedy the situation is by the support platforms in the VAB.

In and out

Whether NASA can still launch in April — its long-held "no later than" commitment to the White House — depends on the outcome of the inspections once back inside the VAB, as well as how long the repairs take and how soon they can roll out again to the launch pad.

The Artemis II crew, including commander Reid Wiseman, pilot Victor Glover and mission specialist Christina Koch of NASA, along with mission specialist Jeremy Hansen with the Canadian Space Agency, had entered their pre-launch quarantine on Friday evening, just hours before the helium flow became an issue. They were released from their quarters on Saturday and will remain at Johnson Space Center in Houston.

"I understand people are disappointed by this development," said Isaacman. "That disappointment is felt most by the team at NASA, who have been working tirelessly to prepare for this great endeavor."

This article will be updated with details and photographs of the Artemis II rollback.