NASA’s Artemis II mission faces potential launch delay due to helium flow issue in SLS rocket

NASA is preparing to potentially move the Space Launch System (SLS) rocket and the Orion spacecraft back to the Vehicle Assembly Building (VAB) at Kennedy Space Center in Florida. This decision comes in response to an unexpected interruption in the helium flow within the rocket’s interim cryogenic propulsion stage (ICPS), which was detected overnight on February 21, 2026.

This issue with the ICPS is leading mission teams to analyze data and develop backup plans, effectively eliminating the previously targeted launch window of March and pushing the timeline toward a potential April launch if the rollback is confirmed. Preparations for the rollback are already beginning, including the removal of pad access platforms that were installed just a day before. These platforms are limited by wind constraints and cannot be dismantled during high winds, which are expected in the coming days.

Following a productive second Wet Dress Rehearsal (WDR), NASA had surprisingly set a target launch date of March 6 for the Artemis II mission. This move was atypical since the agency typically waits until after the completion of a Flight Readiness Review (FRR) before announcing specific launch dates. Hours later, however, the mission’s timeline seemed compromised due to the helium flow issue.

NASA Administrator Jared Isaacman addressed the situation, stating that troubleshooting efforts are in progress. “After overnight data showed an interruption in helium flow in the SLS interim cryogenic propulsion stage, teams are troubleshooting and preparing for a likely rollback of Artemis II to the VAB,” Isaacman said, indicating that the mission’s March launch window is now in jeopardy.

Rumors about a possible vehicle issue surfaced early on Saturday before NASA officially confirmed the problem. This rapid communication reflects the agency’s commitment to transparency, as illustrated by Isaacman’s timely statement online.

The ICPS, an essential component of the SLS rocket’s upper stage, uses liquid hydrogen and liquid oxygen as propellants to provide the thrust necessary for the Orion spacecraft to achieve lunar orbit. Helium is critical in this operation, as it’s used to purge residual gases from the engines and to pressurize the propellant tanks.

According to Isaacman, the helium system in the ICPS functioned well during prior Wet Dress Rehearsals, leaving engineers surprised by the disruption that occurred during routine operations. “This was an unexpected development during routine helium flow operations last evening. The teams were up all night assessing the situation,” he remarked.

Engineers are currently investigating potential causes for this issue, which could mirror a similar malfunction experienced during the uncrewed Artemis I mission in 2022. Potential culprits include problems with the final filter on the umbilical connection, issues with a quick-disconnect interface, or a malfunctioning check valve within the rocket.

Addressing the likelihood of a rollback, Isaacman noted that any repairs would require access that’s only available in the VAB, which has multiple platform levels designed to facilitate maintenance around the rocket.

In the meantime, the vehicle remains safely configured, relying on ground-based systems for engine purging instead of the onboard helium. This anticipated rollback highlights ongoing challenges in preparing for the Artemis mission, as previous delays have often been caused by technical malfunctions, weather conditions, and logistical issues.

If the rollback moves forward, it would mean NASA would miss the March launch window, with April becoming the next possible option, contingent on timely issue resolution. “A rollback would mean NASA will not launch Artemis II in the March launch window,” the agency confirmed, while expressing hope to maintain the April timeline if circumstances allow.

NASA plans to release further updates in the upcoming week regarding the potential rollback and necessary resolutions to ensure the vehicle can return safely to the launch pad, which may also involve conducting tests to confirm system integrity.