NASA hit a snag early Tuesday during a critical test of its enormous moon rocket, raising new questions about whether it will be ready to send four astronauts on a journey around the moon in less than a week.
Engineers detected leaking hydrogen at the tail end of the next-generation Space Launch System rocket, forcing NASA to end its fueling test with around 5 minutes and 15 seconds left in the simulated launch countdown.
The hourslong test, known as a “wet dress rehearsal,” is essentially an elaborate launch day walkthrough, allowing mission managers to assess the performance and readiness of the rocket.
NASA had said it could launch the much-anticipated Artemis II mission to the moon as early as Sunday, but it’s now unclear how the hydrogen leaks may affect that timing. The space agency was expected to set an official launch date after reviewing the outcome of the wet dress rehearsal.
“We’ll take some time after wet dress, we’ll review the data, and then we’ll set up for our launch attempt,” Artemis launch director Charlie Blackwell-Thompson said in a news briefing last month.
During the launch day walkthrough at the Kennedy Space Center in Florida, NASA began fueling the Space Launch System rocket shortly before 12:30 p.m. ET on Monday.
As the booster was filled with more than 700,000 gallons of cryogenic propellant, mission managers twice paused proceedings to investigate leaking hydrogen fuel at the base of the rocket.
After short delays, the fueling resumed and agency officials pressed on with the wet dress rehearsal. Crews at the launch pad simulated loading the astronauts into the Orion spacecraft, which sits atop the moon rocket, and tested its onboard systems and hatches.
The actual astronauts who will be flying around the moon did not participate in the rehearsal, however, as they remain in preflight quarantine in Houston.
At various points during the rehearsal, things appeared to proceed smoothly. But as the test moved into the final 10 minutes before liftoff, the hydrogen leaks became an issue once again.
NASA terminated the test a little after midnight ET on Tuesday, saying that teams were working to secure the rocket and begin draining its tanks.
The space agency is expected to discuss early results from the wet dress rehearsal later on Tuesday, at 12 p.m. ET.
The Artemis II mission is slated to send four astronauts on a 10-day journey around the moon, on a path that will take the crew farther from Earth than any humans have gone before.
NASA had already ruled out the first two launch opportunities (Friday and Saturday) in this month’s window, which extends through Feb. 11.
If the wet dress rehearsal uncovered issues that require additional work, NASA may need to roll the rocket back to its Vehicle Assembly Building, which would likely rule out a launch this month.
The space agency has said there are possible launch windows in March and April, if needed.
Artemis II will be the second trip to space for NASA’s Space Launch System rocket and Orion capsule. But it will be the first time they carry humans, making the mission a crucial step toward realizing NASA’s goal of returning astronauts to the lunar surface.
The Artemis II crew — NASA astronauts Reid Wiseman, Christina Koch and Victor Glover and Canadian astronaut Jeremy Hansen — have spent the last week and half in quarantine at NASA’s Johnson Space Center in Houston to keep them healthy ahead of the mission. They were expected to arrive at Kennedy Space Center Tuesday afternoon, but it’s unclear if those plans will change.
A previous uncrewed Artemis I flight around the moon in 2022 was delayed six months because of hydrogen leaks identified during its first wet dress rehearsal.
