NASA’s Latest Attempt to Resolve Moon Rocket’s Fueling Problems Didn’t Go As Planned

A recent test to confirm repairs to the Space Launch System (SLS) rocket’s fueling system faced problems of its own, casting doubt over NASA’s ability to fix a recurring issue ahead of the Artemis 2 launch window in March.

NASA recently performed a confidence test on newly replaced seals in an area used to load SLS with propellant. During the test, however, operators only partially filled the rocket’s core stage liquid hydrogen tank before encountering an issue with ground support equipment, the agency said in a statement.

The issue somehow reduced the flow of liquid hydrogen into the rocket. “Engineers will purge the line over the weekend to ensure proper environmental conditions and inspect the ground support equipment before replacing a filter suspected to be the cause of the reduced flow,” NASA wrote.

Leaky rockets

The latest confidence test, which the agency hadn’t announced in advance, was meant to address a hydrogen leak on the SLS rocket.

NASA engineers first detected the leak on February 3 during a wet dress rehearsal for Artemis 2. SLS was loaded with liquid hydrogen and liquid oxygen to simulate the launch countdown for the mission. The fueling test was cut short when engineers discovered the issue in one of the tail service mast umbilicals on the mobile launcher. The 35-foot-tall (11-meter-tall) structures provide cryogenic propellant lines and electrical cable connections to the SLS core stage.

In an attempt to resolve the issue, technicians had replaced two seals inside the tail service masts. Although the confidence test of the new seals was only partially successful, NASA teams “were able to gain confidence in several key objectives of the test, and data was obtained at the core stage interfaces, taken at the same time in the test where they encountered a leak during the previous wet dress rehearsal,” the space agency wrote.

A case of deja vu

Those pesky hydrogen leaks also plagued the countdown to the launch of the Artemis 1 mission in 2022, leading to significant delays and a scrubbed launch attempt.

At the time, NASA’s ground teams resolved the issue by changing how the liquid hydrogen was loaded into the rocket’s core stage. The same loading procedure was used for the Artemis 2 wet dress rehearsal, but it didn’t pan out this time.

“Considering the issues observed during the lead-up to Artemis I, and the long duration between missions, we should not be surprised there are challenges entering the Artemis II campaign,” NASA Administrator Jared Isaacman wrote on X. “That does not excuse the situation, but we understand it.”

There is a lot riding on Artemis 2, the first crewed mission to the Moon since the Apollo program ended in 1972. “There is still a great deal of work ahead to prepare for this historic mission,” Isaacman added. “We will not launch unless we are ready and the safety of our astronauts will remain the highest priority.”