NASA Artemis II Launch Facing New Delays Following Helium Flow Discovery

London, 21 February 2026 – NASA’s ambitious timeline to return humans to the vicinity of the Moon has encountered a fresh technical hurdle. Despite the successful completion of a “wet dress rehearsal” on 19 February, engineers have identified a critical issue with the rocket’s helium flow. This discovery, announced today, has cast significant doubt on the previously targeted 6 March launch window, with agency officials now considering a rollback of the Space Launch System (SLS) rocket for further repairs.

Technical Setback Follows Successful Fueling Test

Earlier this week, NASA leadership expressed optimism after the SLS Block 1 rocket successfully completed its second wet dress rehearsal at the Kennedy Space Centre. The test demonstrated the agency’s ability to fuel the massive core stage with liquid hydrogen and liquid oxygen without the leaks that had previously hampered progress. However, the celebratory mood was short-lived. On 21 February, reports emerged of an interruption in the helium flow within the rocket’s upper stage.

Helium is a vital component in rocket propulsion, used to pressurise fuel tanks and operate various valves. The discovery of this “technical glitch” has led NASA Administrator Jared Isaacman and agency engineers to re-evaluate the mission’s readiness. While a 6 March launch was the official target as of yesterday, the latest statements suggest that a rollback to the Vehicle Assembly Building (VAB) may be necessary to resolve the helium issue, which would effectively close the early March launch window.

The Artemis II Mission Objectives

Artemis II is designed to be the first crewed mission of the Artemis programme, carrying three American astronauts and one Canadian astronaut on a 10-day journey around the Moon. This mission serves as a critical precursor to Artemis III, which aims to land the first woman and the next man on the lunar surface. The SLS remains the only launch vehicle capable of sending the Orion spacecraft, its crew, and necessary cargo directly to a trans-lunar trajectory in a single launch.

Key Facts: Space Launch System (SLS) & Artemis II

The following table outlines the technical specifications and current status of the Artemis II mission hardware based on official NASA documentation.

Frequently Asked Questions

Why is helium important for the SLS rocket?

Helium is used to maintain pressure in the propellant tanks as the fuel is consumed and to actuate pneumatic valves. A failure in helium flow can prevent the rocket engines from operating correctly or lead to structural issues within the tanks during flight.

Will the Artemis II mission still launch in March?

While NASA officially targeted 6 March 2026 following the successful fueling test on 19 February, the discovery of the helium flow issue on 21 February makes a March launch increasingly unlikely. If the rocket requires a rollback to the assembly building, the launch will be postponed to a later window.

What was the outcome of the wet dress rehearsal?

The rehearsal on 19 February was largely successful, as NASA confirmed they had fixed previous liquid hydrogen leaks. The team successfully completed the countdown and fueling procedures, which were the primary goals of the test before the helium issue was subsequently identified.