NASA just fueled up its Artemis 2 moon rocket in 2nd critical test. Was it a success? (It sure looked like it.)

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NASA's second attempt to fuel up its Artemis 2 moon rocket appeared to go well on Thursday (Feb. 19), potentially keeping the mission on track to launch as soon as early March.

The space agency wrapped up the Artemis 2 wet dress rehearsal (WDR) — a two-day-long practice run of the operations leading up to launch — on Thursday night (Feb. 19) at Kennedy Space Center (KSC) in Florida.

The Artemis 2 team notched a number of important milestones during the test, chief among them the successful fueling of the mission's Space Launch System (SLS) rocket.

The WDR is designed to put Artemis 2's SLS, Orion capsule, ground equipment and mission teams through their paces, ensuring that everything is ready for an actual liftoff.

That launch will send four astronauts — NASA's Reid Wiseman, Victor Glover and Christina Koch and the Canadian Space Agency's Jeremy Hansen — on a 10-day trip around the moon and back to Earth. Artemis 2 will be the first human spaceflight beyond low Earth orbit since the Apollo missions ended in 1972, as well as the first crewed mission of NASA's Artemis program.

The lone previous Artemis mission, Artemis 1, successfully sent an uncrewed Orion to lunar orbit and back in late 2022. That flight was delayed multiple times by leaks of liquid hydrogen (LH2) propellant during ground testing, and it looked like Artemis 2 might be heading down a similar path.

NASA cut short Artemis 2's first WDR on Feb. 2 after detecting an LH2 leak, which emanated from an interface with the tail service mast, a part of the SLS' mobile launch tower that supplies fuel and other resources to the rocket via lines known as umbilicals. The Artemis 1 leak came from this same trouble spot.

The Artemis 2 team replaced two seals in the area after the first WDR attempt, then partially filled the rocket's tanks on Feb. 12 to test the fix. The seals held then, and they held on Thursday: Team members successfully filled SLS' two stages with 730,000 gallons (2.76 million liters) of supercold LH2 and liquid oxygen "without exceeding the ground safety limit of the hydrogen leak concentration," according to a NASA update.

Launch teams checked off other important WDR boxes on Thursday as well — for example, closing the Orion crew module hatch and ensuring that the capsule's emergency-escape system was secure. They then ran through "terminal count" twice, taking the countdown clock to T-33 seconds and then to T-29 seconds.

"During terminal count, automated systems take control of countdown operations, final checks of flight computers, engine bleed systems, and ground support equipment occur, and the rocket transitions to internal power, and the countdown proceeds toward simulated engine start," NASA officials wrote in an another WDR update.

The WDR came to an end at 10:16 p.m. EST (0316 GMT on Feb. 20) with the completion of the second terminal count.

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Not everything went perfectly on Thursday; for instance, the second terminal count was paused briefly due to a "booster avionics system voltage anomaly." But getting through the WDR may keep Artemis 2 on track to lift off in the next available window, which runs from March 6 to March 9 and also includes March 11. (A subsequent window opens in the beginning of April.)

We should learn more on Friday: NASA will hold a press conference at 11 a.m. EST (1600 GMT) to discuss the results of the WDR and the plan for Artemis 2 going forward. You can watch that live here at Space.com.

Editor's note: This story was updated at 11:15 p.m. ET on Feb. 19 to state that the WDR was completed.