NASA Artemis 1 moon mission launch called off due to technical snag

The launch of National Aeronautics and Space Administration (NASA) moon mission Artemis 1 has been called off as the team is working on an issue with an engine, the US space agency tweeted.

"Teams are in a hold in the countdown at T-40 minutes while engineers continue to assess an issue conditioning engine 3, one of four RS-25 engines on the bottom of the Space Launch System rocket's core stage. Engineers are looking at options to gather as much data as possible," the official NASA blog said.

Launch controllers condition the engines by increasing pressure on the core stage tanks to bleed some of the cryogenic propellant to the engines to get them to the proper temperature range to start them. 

Engine 3 is not properly being conditioned through the bleed process, and engineers are troubleshooting.

Teams also are assessing what appears to be a crack in the thermal protection system material on one of the flanges on the core stage.

The flanges are connection joints that function like a seam on a shirt, are affixed at the top and bottom of the intertank so the two tanks can be attached to it.