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Scrubbed Again: NASA Calls Off Second SLS Launch Attempt Due to Hydrogen Leak

NASA's return to the Moon is delayed yet again, after engineers failed to plug a hydrogen leak on the launch pad Saturday.

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NASA’s Space Launch System (SLS) rocket with the Orion spacecraft aboard is seen atop the mobile launcher at Launch Pad 39B, Tuesday, Aug. 30, 2022, at NASA’s Kennedy Space Center in Florida.
The SLS rocket awaits its launch atop Launchpad 39B at Kennedy Space Center in Florida.
Photo: NASA/Joel Kowsky

Update: 11:23 a.m. ET: Today’s launch has been scrubbed on account of the hydrogen leak. Launch director Charlie Blackwell-Thompson formally agreed to the scrub at 11:19 a.m ET. The rocket, which remains in a safe configuration, will now be drained of the ultra-cold propellants. We now await word on whether NASA will re-attempt the launch on Monday or if the rocket needs to be rolled back to the Vehicle Assembly Building for repairs.

Update: 11:12 a.m. ET. Teams recommended a no-go for today’s launch shortly before 11:00 a.m. ET., but launch director Charlie Blackwell-Thompson did not give her approval for a scrub. Blackwell-Thompson wants to discuss matters with the team prior to giving up.


Update 10:28 a.m. ET: NASA’s Derrol Nail just said on the livestream, “The second attempt at a warmup of the connection with the hydrogen line did not work... When they added any pressure at all, they saw the leak return.” The engineering team is now discussing next steps.

Update 10:17 a.m. ET: Engineers have manually opened a valve to resume the flow of liquid hydrogen into the tank. They’ll be checking to see if their troubleshooting plan, in which they stopped flow to allow the connection to warm up, succeeded in sealing the previously detected leak.

NASA Live: Official Stream of NASA TV

Update 10:08 a.m. ET: NASA is troubleshooting a detected leak in the 8-inch liquid hydrogen line during fuel loading this morning.


NASA’s Derrol Nail said on the livestream that NASA engineers are attempting a troubleshooting plan in which they stop the flow of hydrogen to allow the connection to warm up, “try to re-seat that bullnose connector into the seal at that connection point for the 8-inch hydrogen line.” He referred to this as Plan A, “a plan they are knowledgeable about and are experienced with.”

Original article appears below.

NASA ground crews are ready to try again to get the enormous Space Launch System off the ground. On Saturday, September 3, the space agency will make a second attempt at launching the uncrewed Artemis 1 mission to the Moon and back. You can catch the action live right here.


Blast off is slated for 2:17 p.m. (all times Eastern Standard Time) on September 3, with the launch window closing two hours later. Forecasts show a 60% chance of favorable weather at the beginning of the launch window, which increases to 80% by the end of the two-hour cutoff, NASA officials told reporters during a press briefing on Friday.

NASA will begin live coverage of the launch activities at 12:15 p.m. (1:00 p.m. for coverage in Spanish) on the space agency’s YouTube channel, the NASA app, and the agency’s website.


“There’s no guarantee that we’re going to get off on Saturday, but we’re gonna try,” Mike Sarafin, Artemis mission manager, said during a news conference on Thursday.

Eager viewers can start watching the tanking operations to load propellants into the rocket at 5:45 a.m. Assuming the launch happens on Saturday, NASA will hold a post-launch news conference at 6 p.m. that will feature NASA Administrator Bill Nelson. Coverage of the mission will continue until 9:45 p.m., when the Orion capsule is expected to make its first outbound trajectory burn as it sets a course for the Moon (this timing may vary depending on when the rocket actually takes off).


The inaugural flight of NASA’s SLS suffered a slight hiccup during its first launch attempt on August 29 when one of the core stage’s four RS-25 engines failed to reach the ultra-cold temperatures required for liftoff. Further analysis confirmed the problem as being caused by a faulty sensor, and that the engine itself very likely reached the desired cryogenic temperature. For Saturday’s launch, teams on the ground will initiate the engine chill-down procedure earlier than usual, according to Sarafin.

The 322-foot-tall (98-meter) rocket is currently sitting atop Launchpad 39B at the Kennedy Space Center in Florida, and with the Orion spacecraft on top. The Artemis 1 mission is the first integrated flight of SLS and Orion. The SLS rocket will boost the uncrewed capsule to orbit, from where it will travel on its own and perform a close flyby of the Moon before returning to Earth. Artemis 1 is meant to set the stage for a crewed Artemis 2 mission in 2024 that will make a similar journey to the Moon, but without landing on the lunar surface. That’s the job of Artemis 3, which is scheduled for late 2025. Through the Artemis program, NASA is attempting to maintain a sustainable human presence on the Moon that may one day allow us to go to Mars.


But first, SLS needs to make it off the launchpad. If Saturday’s launch is a no-go, then NASA may attempt another liftoff on Monday, September 5, or Tuesday, September 6. After that, the SLS rocket would need to be rolled back to the Vehicle Assembly Building for further testing, Sarafin told reporters on Friday.

More: Scrubbed Artemis 1 Launch Prompts Concerns About Unfinished Rehearsals