2022-08-29 21:05:32
NASA calls off Artemis 1 moon rocket launch over engine cooling issue
CAPE CANAVERAL, Fla. — An engine cooling issue on NASA's giant new rocket for deep-space exploration forced the agency to call off the booster's much-anticipated launch debut early Monday (Aug. 29).
NASA had mostly fueled its first Space Launch System (SLS) megarocket to launch the Artemis 1 moon mission on Monday when launch controllers were unable to chill one of the four main engines to the temperatures needed to handle its super-cold propellant. The issue stalled plans to launch the SLS rocket and its uncrewed Orion spacecraft on an ambitious 42-day test flight around the moon. Liftoff was scheduled for 8:33 a.m. EDT (1233 GMT).
Chilling the SLS rocket's engines before flowing cryogenic liquid hydrogen and liquid oxygen through them is a required step before the rocket can launch, NASA officials said. While three of the engines passed that test, Engine No. 3 did not, despite troubleshooting efforts.
"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," NASA officials said in a statement. "Engine 3 is not properly being conditioned through the bleed process, and engineers are troubleshooting."
All four of these engines flew on NASA's space shuttle program of reusable vehicles.
According to NASA spokesperson Derrol Nail, the engine conditioning was not something that the team was able to verify during the "wet dress rehearsal" process that concluded in June.
"This is something they wanted to test during Wet Dress 4 but were unable to," Nail said. "So this was the first opportunity for the team to see this live in action. It's a particularly tricky issue even going in to get that temperature dialed in, according to engineers."
The Engine No. 3 conditioning issue cropped up as NASA worked through a series of glitches during the countdown, including a liquid hydrogen leak early in the fueling process and a possible crack in a part of core booster known as the intertank flange, which connects the SLS's giant liquid hydrogen and liquid oxygen tanks. The tanks can hold a combined 730,000 gallons (3.3 million liters) of propellant.
"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," NASA said in the update.
NASA engineers found that the crack was actually in the insulating foam on the flange, not in the rocket's metal structure. "That ice that formed is essentially air that's being chilled by the tank that gets trapped inside of a crack in the foam but not the actual tank," Nail said.
Nail added that NASA personnel had seen similar cracks in the foam when it was used on the space shuttles before their retirement in 2011.
The Engine No. 3 problems and the feared crack followed concerns about a liquid hydrogen leak in the rocket. The leak during the fueling process appeared similar to one that occurred during an SLS fueling test earlier this year, Nail noted. But NASA officials were not quick to judge.
"Although a similar issue was identified in an earlier wet dress rehearsal, it may not necessarily be the same cause," NASA officials wrote in a subsequent update.
NASA stopped and restarted the flow of liquid hydrogen into the tank in an attempt to verify the leak and even proceeded with fueling the 322-foot-tall (98 meters) rocket's upper stage while engineers worked the issue.
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