After an attempt earlier this month, NASA is now aiming for Thursday for the Artemis 2 mission’s final fuel test and simulated launch countdown.
The Artemis 2 Space Launch System (SLS) rocket and Orion spacecraft at NASA’s Kennedy Space Center in Florida on Feb. 1, moments after the countdown began for the mission’s first wet dress rehearsal. Credit: NASA/John Cross
NASA is aiming for a second Artemis 2 wet dress rehearsal tanking day for Thursday, Feb. 19, after an attempt failed due to a liquid hydrogen leak earlier this month.
Artemis 2 represents humanity’s return to the Moon for the first time in more than 50 years, but it can’t leave the ground until it passes one final hurdle – a wet dress rehearsal.
The upcoming wet dress rehearsal attempt follows several days of testing and repair. Following the initial wet dress rehearsal on February 3, technicians replaced two seals near the “tail service mast umbilical” – the three-story structure that connects the refueling lines to the rocket – where the leaked hydrogen was detected.
To verify those improvements, NASA conducted a partial refueling on February 12. While the new seals performed as expected, a separate issue arose when a filter in the ground-side instrument restricted the flow of liquid hydrogen. Engineers replaced that filter and prepared the system for this second full-scale rehearsal.
While the primary refueling activities take place on Thursday, the official countdown begins tonight at 6:40 PM EST. Launch controllers will arrive at Kennedy Space Center to begin a two-day countdown, which will run until the corresponding launch time of 8:30 p.m. on Feb. 19.
NASA will not set a specific launch date until the results of the second wet dress rehearsal are clear, but the earliest available launch window will open on March 6.
The wet dress rehearsal is the final test before launch. For Artemis 2, engineers will load approximately 700,000 gallons of cryogenic liquid fuel into the SLS rocket and simulate a full launch countdown, running through several possible launch scenarios, such as holding the countdown timer or recycling. Although astronauts will not be onboard, a special ground team will be on the pad to practice specific steps for sealing the Orion spacecraft’s hatch.
The second attempt will also follow the same script as the first. The team will attempt to race twice in the final ten minutes before launch, a window known as the terminal countdown. They would stop the countdown at T-1 minutes and 30 seconds, hold the countdown for three minutes, then restart the countdown before stopping it again at T-33 seconds. Then, operators will repeat the countdown back to T-10 minutes and run the terminal countdown one last time before emptying the fuel tanks and completing the test.
Wet dress rehearsals not only allow the team to practice for real-world scenarios that could hinder the launch, but they also allow them to pause the countdown to troubleshoot any issues that arise in real time.
During the first Artemis 2 wet dress rehearsal, unexpected problems with a liquid hydrogen leak caused unplanned interruptions and ultimately ended the test. While engineers initially managed to troubleshoot the temperamental fuel line problem by heating the hardware interface and allowing the seal to be reinstalled, the leak reoccurred. A spike in fuel levels recorded at the T-5 minute 15-second mark forced officials to perform planned recycling or abort the remainder of the rehearsal before converting the rocket to its own internal power. Completing those incomplete objectives is now a high priority for the upcoming examination to be held on February 19.
