(CNN) — NASA has once again waved off an attempt to launch its massive new moon rocket on an uncrewed test mission because of technical issues. The scrub was called at 11:17 a.m. ET, three hours before the beginning of the launch window.
Artemis I had been slated to take off Saturday afternoon, but those plans were scrubbed after team members discovered a liquid hydrogen leak that they spent the better part of the morning trying to resolve. Liquid hydrogen is one of the propellants used in the rocket’s large core stage. The leak prevented the launch team from being able to fill the liquid hydrogen tank despite trying various troubleshooting procedures.
It’s the second time in a week that the space agency has been forced to halt the launch countdown in the face of technical issues. The first launch attempt, on Monday, was called off after several issues arose, including with a system meant to cool the rocket’s engines ahead of liftoff and various leaks that sprung up as the rocket was being fueled.
The liquid hydrogen leak was detected Saturday at 7:15 a.m. ET in the quick disconnect cavity that feeds the rocket with hydrogen in the engine section of the core stage. It was a different leak than one that occurred ahead of the scrubbed launch on Monday.
The launch controllers warmed up the line in an attempt to get a tight seal and the flow of liquid hydrogen resumed before a leak reoccurred. They stopped the flow of liquid hydrogen and proceeded to “close the valve used to fill and drain it, then increase pressure on a ground transfer line using helium to try to reseal it,” according to NASA.
That troubleshooting plan was not successful. The team attempted the first plan again to warm up the line, but the leak reoccurred after they manually restarted the flow of liquid hydrogen.
There was a 60% chance of favorable weather conditions for the launch, according to weather officer Melody Lovin.
The Artemis I stack, which includes the Space Launch System rocket and Orion spacecraft, continues to sit on Launchpad 39B at Kennedy Space Center in Cape Canaveral, Florida.
The Artemis I mission is just the beginning of a program that will aim to return humans to the moon and eventually land crewed missions on Mars.
There is still a backup opportunity for the Artemis I mission to launch on September 5 and 6.
In the last few days, the launch team has taken time to address issues, like hydrogen leaks, that cropped up ahead of Monday’s planned launch before it was scrubbed. The team has also completed a risk assessment of an engine conditioning issue and a foam crack that also cropped up, according to NASA officials.
Both were considered to be acceptable risks heading into the launch countdown, according to Mike Sarafin, Artemis mission manager.
On Monday, a sensor on one of the rocket’s four RS-25 engines, identified as engine #3, reflected that the engine could not reach the proper temperature range required for the engine to start at liftoff.
The engines need to be thermally conditioned before super-cold propellant flows through them prior to liftoff. To prevent the engines from experiencing any temperature shocks, launch controllers gradually increase the pressure of the core stage liquid hydrogen tank in the hours before launch to send a small amount of liquid hydrogen to the engines. This is known as a “bleed.”
The team has since determined it was a bad sensor providing the reading — they plan to ignore the faulty sensor moving forward, according to John Blevins, Space Launch Systems chief engineer.
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