NASA Fixes Hydrogen Leaks on Artemis II Rocket After Test Delay

NASA engineers at Kennedy Space Center in Florida repaired hydrogen leaks on the Artemis II rocket after a major practice test on February 3, 2026. The leaks, found in fuel lines connected to the launch platform, delayed the first crewed Moon mission in over 50 years. Teams replaced seals and plan more tests before a possible March launch.

Background

The Artemis program aims to return humans to the Moon. Artemis II will send four astronauts on a trip around the Moon without landing. The rocket, called the Space Launch System or SLS, stands 322 feet tall and uses liquid hydrogen and liquid oxygen as fuel. These fuels are kept at very low temperatures, around minus 423 degrees Fahrenheit for hydrogen.

This is not the first time hydrogen leaks have hit the SLS. During Artemis I in 2022, the uncrewed test flight, similar leaks happened at the same spot. That rocket had to roll back to a huge building three times over six months for fixes. Engineers made changes after that, but the problem showed up again on Artemis II.

The wet dress rehearsal is a full practice run. Teams load over 700,000 gallons of fuel, go through the countdown, and stop just before launch. For Artemis II, the test started January 31 and ran until February 3. It checked the rocket, ground systems, and team readiness for real launch day.

Cold weather at the site did not cause the leaks. Heaters kept the Orion spacecraft warm on top of the rocket. Teams also fixed a valve on the crew hatch and dealt with some audio issues during the test.

Key Details

The leaks appeared early during fueling on February 2. They came from the tail service mast umbilical, a set of lines that carry hydrogen fuel and electrical signals from the launch platform to the rocket. These lines pull away right before liftoff.

Engineers drained the cold fuel and found high hydrogen levels in the lines. They removed connecting plates and saw the rubber seals had issues. Technicians replaced two seals to stop the leaks.

The test reached full fueling on the first try, which teams called a success for data collection. They got to within five minutes and 15 seconds of simulated liftoff. But a spike in hydrogen forced them to stop the countdown. Safety rules set a leak limit at 16% hydrogen concentration in that area.

Teams tried warming the area by pausing the hydrogen flow. They also changed the flow rate. These steps worked enough to keep going for hours, but the leak never fully went away. In the end, they drained the fuel safely.

Repair Work and Changes

Repair work finished by February 9. Engineers looked at the old seals to learn more. They plan tests at Stennis Space Center in Mississippi to check the new seals under real conditions.

For the next rehearsal, teams changed some steps. The Orion hatch will close sooner. The crew bridge stays on longer. Ground crew skips some non-key tasks. They added extra time during fueling for fixes if needed. The countdown will take a bit longer, but it fits the astronauts' schedule.

"The fact that we got to full tanking yesterday on the first try was a tremendous success, and we gathered an enormous amount of data." – NASA official during test review

NASA says the SLS is like an experimental vehicle. Each one has unique parts. Hydrogen is a small molecule that leaks easily, and the connections are complex. Years between tests make it hard to predict issues.

What This Means

The leaks push the Artemis II launch to no earlier than March 2026. A final date comes after the next test and a safety review. Repairs happened at the pad, so no need to move the rocket back to the assembly building. That saves time compared to Artemis I.

Managers believe they can fix this without big delays. They stabilized the leak within limits during the test, unlike before. Still, the repeat problem raises questions about hydrogen handling on SLS.

Artemis II crew includes Reid Wiseman, Victor Glover, Jeremy Hansen, and Nichole Ayers. They trained for years. The mission tests Orion spacecraft systems for longer trips, like Artemis III which plans a Moon landing.

More tests will check if seals hold. Engineers watch hydrogen systems closely. Any new issues could mean more changes. The program moves forward, but safety comes first for the crew.

Teams stress the data from this test helps future flights. They learned how to handle leaks better and improved procedures. NASA keeps an aggressive approach to fuel issues.

The Kennedy Space Center stays busy. Technicians reconnect lines and prep for the next run. Stennis tests add confidence. All eyes stay on getting astronauts safely around the Moon.