Trevor Mahlmann
11:15 a.m. ET Saturday: NASA officially canceled Saturday’s Artemis I launch attempt. The launch team was unable to fix a leak in an 8-inch hydrogen inlet to the Space Launch System rocket.
Launch officials tried three troubleshooting measures, and none were able to significantly reduce the leak of cryogenic hydrogen as it spilled out of ground systems aboard the missile.
It’s not clear whether NASA will attempt to launch the Artemis I mission on Monday or Tuesday, or whether the massive rocket will have to roll back to the Vehicle Assembly Building for repairs. The latter seems most likely, but a final decision has not yet been made. Ars will have a full recap story later on Saturday.
KENNEDY SPACE CENTER, Fla.—Five days after NASA’s first attempt to fly the massive Space Launch System rocket ended with technical problems, the space agency is ready to try again.
A launch team began fueling the rocket on Saturday morning, shortly before the sun began to rise over the Atlantic Ocean waters surrounding the spaceport. The SLS rocket, which launches the Artemis I mission around the moon, has a two-hour launch window that opens at 2:17 p.m. ET (18:17 UTC).
A successful launch marks the beginning of a 42-day mission that will send the Orion spacecraft into orbit around the moon and test critical technologies, such as a heat shield that will protect the spacecraft during a fiery reentry through Earth’s atmosphere. If the mission goes well, Artemis II would follow in a few years and transport humans around the moon. A moon landing is planned for later this decade.
A lot will have to happen before the rocket can be launched on Saturday. There are three main reasons why rocket launches stumble: the weather, range issues, and technical issues. The weather is looking pretty good for a Florida summer afternoon, with at least a 60 percent chance of favorable conditions. Launch range issues, such as a boat sailing in restricted waters, are a slim chance.
That leaves technical issues behind, and because the SLS is a complex, towering rocket with leaking hydrogen fuel, trying to launch for the first time — well, let’s just say a scrub is more likely than not. Prior to launch, there are no fewer than 489 “launch commit criteria” that the SLS rocket must meet, such as propellant temperatures, tank pressures, and so on.
“There’s no guarantee we’ll leave on Saturday, but we’re going to try,” NASA engineer Mike Sarafin, who serves as mission manager for Artemis I, said at a news conference this week.
Monday’s scrub
The launch team decided to scrap Monday’s attempt even before the launch window opened after a series of issues delayed the countdown and smeared launch controllers. Storms pushed back the start of refueling; then there was a leaking hydrogen inlet leading to the rocket, and an ice problem in the booster foam insulation.
But the biggest problem came when launch controllers attempted to cool down the four main RS-25 engines, which must be at a very cold temperature of -420 degrees Fahrenheit at launch to avoid the extremely cold propellants when the engine is ignited. can process. A sensor in one of the four motors indicated that it was not cooling to the correct temperature.
At the Launch Control Center, some NASA engineers believed the sensor was the cause, as there were other indications that the engine was cooling down as required. But time was running out, and given the other issues the launch team was working with, it was getting too much, Sarafin said.
“One of the worst things you can do when you’re in a dangerous state is to go further off the script,” Sarafin said. “The team definitely did the right thing on Monday.”
On Tuesday, technicians and engineers worked on the vehicle and its ground systems, gaining confidence that it was indeed a problematic sensor that had failed, rather than a chill-down problem. One of the key indicators was that liquid hydrogen had flowed through the engine and left at an expected temperature.
So for Saturday’s attempt, NASA not replacing the sensor, which would require a rollback to the Vehicle Assembly Building and a delay of at least a month, if not longer. If there’s a scrub on Saturday for whatever reason, NASA could still have a chance to launch the vehicle on Monday or Tuesday, before it has to be rolled back for repairs anyway.
The official webcast for the mission begins Saturday at 11:15 a.m. ET (3:15 p.m. UTC). It is embedded below. NASA’s media outlet will cover tank operations, with live, intermittent commentary starting at 5:45 a.m. ET (9:45 UTC) on Saturday.
Official NASA webcast for the Artemis I mission.
