NASA scrubbed a second launch attempt of the Artemis I mission to the Moon on Saturday due to a large liquid hydrogen leak that posed a potential fire hazard. Liquid hydrogen converted to gas leaked into the atmosphere, reaching two to three times the level NASA deems safe.
Another launch attempt could take place in late September or late October, NASA officials said, but they will make that decision in coming days in coordination with Kennedy Space Center launch range officials. A SpaceX launch is scheduled for early October that could interfere with further Artemis I launch plans.
Officials suggested it could take weeks to make repairs and charge batteries if the 320-foot-tall structure is wheeled back to the Vehicle Assembly Building at the Kennedy Space Center. Alternatively, repairs may be made at the launch pad, but engineers need to assess the pros and cons of working in a temporary structure at the pad during foul weather with lightning, a fairly common occurrence on the Florida coast.
The liquid hydrogen leak was discovered at 7:15 a.m. Saturday while crews were loading liquid hydrogen propellant into the SLS rocket’s core stage. The leak defied three repair attempts by engineers who tried to resume filling the rocket’s humongous core tank. The leak was large enough that it exceeded safe flammability limits by two or three times, according to Mike Sarafin, Artemis mission manager.
Artemis launch director Charlie Blackwell-Johnson declared the launch attempt scrubbed at 11:17 a.m. EDT after more than three hours of attempts to fix the liquid hydrogen leak. Crews then began draining propellants from the tank and said the SLS rocket was safe.
NASA Administrator Bill Nelson said launch delays are to be expected, "Be ready for scrubs," he said on NASALive after the scrub was called. "We'll go when it's ready to go and don't go until it's ready." H recalled a time in 1986 when he was a payload specialist aboard a Space Shuttle Columbia flight that endured four scrubs before a successful launch on the fifth try.
About 33% of launch attempts are scrubbed with half of those scrubs due to weather and the other half due to other factors, officials said earlier in the week. Asked by a reporter what the financial cost of two scrubs would tally, Nelson responded, "the cost of two scrubs is a lot less than a failure."
Sarafin said a bad gasket may have caused the leak on a line connection known as a quick disconnect carrying liquid hydrogen into the core tank of the SSL rocket. The leak might have occurred during a manual operation of the tank fill operation when too much pressure was applied to the liquid hydrogen filling operation, but further investigation will be required to be sure.
About 11% of the core tank had been filled with liquid hydrogen when the leak was detected at 7:15 a.m. EDT Saturday. NASA said 100% of liquid oxygen had filled the rocket’s core tank by the time the scrub was declared.The launch had been expected to occur at 2:17 p.m. EDT.
An earlier launch attempt on Monday was also scrubbed after two small leaks were detected and a faulty sensor recorded an engine had not reached the proper cold temperature of minus-423 degrees F.