Nasa fixes helium leak on Artemis II rocket: When will astronauts launch to Moon?

Nasa is gearing up to send four astronauts around the Moon, but first, it had to fix a tiny, leaky seal on the world’s most powerful rocket.

The space agency announced on March 3 that technicians have successfully repaired a fault in the upper stage of the SLS (Space Launch System) rocket at the Kennedy Space Center in Florida.

The rocket, paired with the Orion spacecraft, is at the heart of the Artemis II mission, which aims to fly astronauts around the Moon for the first time since Apollo 17 in 1972.

WHAT WENT WRONG WITH THE ARTEMIS II ROCKET?

The trouble began after a wet dress rehearsal on February 21, during which engineers discovered that helium was not flowing properly to the rocket’s upper stage. A seal inside the quick disconnect, a mechanism that links ground supply systems to the rocket, had become dislodged and was blocking the helium pathway entirely.

Nasa's SLS rocket carrying the Orion spacecraft sits inside the Vehicle Assembly Building at Kennedy Space Center, Florida, as technicians work to fix a helium flow fault ahead of the Artemis II Moon mission. (Photo: Nasa) — Nasa’s SLS rocket carrying the Orion spacecraft sits inside the Vehicle Assembly Building at Kennedy Space Center, Florida. (Photo: Nasa)

Helium is critical to rocket operations. It is used to pressurise fuel tanks, purge lines, and keep components operating safely during launch. Without it flowing correctly, the rocket simply cannot fly.

Technicians removed the faulty quick disconnect, reassembled the system, and ran helium through at a reduced flow rate to confirm the fix had worked. Engineers are now investigating why the seal came loose in the first place, so the issue does not repeat itself.

WHAT ELSE IS NASA FIXING BEFORE LAUNCH?

While the helium repair was underway, teams took the opportunity to refresh several other systems. Flight termination system batteries have been replaced and are being retested end-to-end. Fresh flight batteries are also going into the upper stage, core stage, and solid rocket boosters. The Orion launch abort system batteries are being recharged as well.

A close-up view of the SLS rocket's upper stage, where a dislodged seal inside the quick disconnect mechanism blocked helium from flowing properly during a wet dress rehearsal on February 21, 2026. (Photo: Nasa) — A close-up view of the SLS rocket’s upper stage, where a dislodged seal inside the quick disconnect mechanism blocked helium from flowing properly during a wet dress rehearsal on February 21, 2026. (Photo: Nasa)

Since March 2, workers have also been replacing a seal on the core stage liquid oxygen line feed system and will run integrity tests once complete.

Nasa plans to roll the rocket back out to Launch Complex 39B later this month, with a potential launch window opening in April. When it finally lifts off, Artemis II will mark a defining moment in humanity’s return to deep space.