Artemis II Wet Dress Rehearsal Succeeds — Then a Helium Problem Grounds the March Launch

Published February 23, 2026  |  SpaceX & Space Industry

NASA hit a major technical milestone late on February 19, 2026, when the Space Launch System (SLS) rocket completed its second Wet Dress Rehearsal for the Artemis II mission — holding at T-29 seconds exactly as planned. It was a clean run after hydrogen leak repairs from the first WDR attempt proved successful. But within 48 hours, a separate issue with helium flow to the rocket's upper stage changed the picture entirely, forcing a rollback to the Vehicle Assembly Building and ruling out a March launch.

Here is a full breakdown of what went right, what went wrong, and where the mission stands now.

📊 Key Figures

The WDR: What Went Right

The second Wet Dress Rehearsal unfolded over two days and represented a genuine step forward for the program. The most significant technical hurdle coming in was the hydrogen leak that had plagued the first WDR attempt. Teams had replaced the quick disconnect fueling connection seals on the liquid hydrogen side, and the fix held — only very minimal leakage was observed during propellant loading. That is a meaningful engineering win.

Engineers successfully loaded more than 700,000 gallons of liquid hydrogen and liquid oxygen into the rocket's core stage and interim cryogenic propulsion stage (ICPS). The countdown then proceeded to T-33 seconds before pulling back to a planned hold at T-29 seconds — the defined success criterion for this rehearsal.

▶ Watch Video on X

▶ Watch Video on X

NASASpaceflight confirmed completion on X: the WDR was done, the planned hold achieved, and the data now flows to the Flight Readiness Review process. No launch date would be set until that review was complete — which, at the time, seemed like routine caution.

The Helium Problem: What Went Wrong Next

Overnight between February 20 and 21, engineers conducted a routine repressurization operation on the ICPS upper stage. During that process, they observed an interrupted flow of helium to the stage — helium being the inert gas used to pressurize propellant tanks and manage internal pressure systems. This is not a trivial issue. Helium systems are critical to safe propellant management during launch operations, and any anomaly requires full investigation before the vehicle can fly with crew aboard.

The consequence is direct: the SLS and Orion stack must roll back from Launch Complex 39B to the Vehicle Assembly Building at Kennedy Space Center for troubleshooting and repair. That rollback process — combined with repair time, re-stacking, and the required Flight Readiness Review — makes any launch attempt in March 2026 physically impossible. NASA Administrator Jared Isaacman confirmed the situation publicly, acknowledging that March is no longer on the table.

According to reporting from Spaceflight Now, the earliest realistic launch opportunities are now April 1, 3, 4, 5, and 6, 2026. Those dates remain targets, not commitments — they are contingent on the repairs going smoothly and the Flight Readiness Review clearing the vehicle.

The Crew

The Artemis II crew — NASA astronauts Reid Wiseman (Commander), Victor Glover (Pilot), Christina Koch (Mission Specialist), and Canadian Space Agency astronaut Jeremy Hansen (Mission Specialist) — entered crew quarantine in Houston on February 20, the same day the WDR completed. They are the first humans assigned to fly to the Moon since Apollo 17 in December 1972. The delay does not affect their readiness; crew quarantine protocols will adjust to the updated schedule.

🔭 The BASENOR Take

📰 Deep Dive

The Wet Dress Rehearsal is intentionally designed to expose exactly the kind of issues that have now surfaced — first the hydrogen leaks in WDR 1, now the helium anomaly found in the hours after WDR 2. That is the system working as intended. The alternative — discovering these issues during an actual launch attempt with crew aboard — is not an acceptable outcome. NASA's methodical approach, frustrating as the delays are, reflects the reality of flying humans on a vehicle that has not yet carried a crew.

The ICPS helium system issue is particularly notable because the interim cryogenic propulsion stage is the element responsible for sending the Orion capsule and its crew on the trans-lunar injection burn — the burn that sends them from Earth orbit toward the Moon. Getting that stage's pressurization systems right is not optional. There is no redundancy for a bad helium system at that point in the mission profile.

For context, the Artemis program has operated under severe schedule pressure since the first SLS launch in November 2022. Artemis I's uncrewed test flight took years longer than originally planned. Artemis II was subsequently pushed from 2024 to 2025 to 2026. Each delay adds cost and political scrutiny. A move from March to April is not catastrophic in the broader arc of the program, but it does narrow the margin for any further problems before the end of the current fiscal and political cycle in Washington.

The crew entering quarantine on the day of the WDR completion — a sign of how close NASA felt the launch was — underscores just how quickly this situation evolved. Within 24 hours, optimism about a March launch date turned into a confirmed rollback. That speed of change is a useful reminder for anyone following the program: in rocketry, the status can shift dramatically between morning and evening. The next major update will come once engineers have assessed the helium system in the VAB and NASA sets a formal Flight Readiness Review date.