CAPE CANAVERAL, Fla. – NASA engineers are working to stop a fuel leak on its massive new moon rocket ahead of a critical test flight on Saturday (Sept. 3).
NASA began refueling the Artemis 1 moon rocket, NASA’s first Space Launch System (SLS), early Saturday to launch an unmanned Orion spacecraft to the moon from Pad 39B here at Kennedy Space Center at 2:17 p.m. EDT (1817 GMT). But an ongoing leak of liquid hydrogen fuel detected has delayed launch preparations.
NASA has a two-hour window to launch the mission, with promising weather forecasts ranging between 60% and 80% “go,” the agency said. You can watch the launch live online.
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The hydrogen leak was first discovered at 7:15 a.m. EDT (1115 GMT) when NASA began filling the massive SLS rocket with the 730,000 gallons of liquid hydrogen and liquid oxygen propellant needed for launch. The leak is in the connection point of an 8-inch hydrogen fuel line near the engine compartment at the base of the 32-story rocket.
Engineers first tried to warm up and cool the connector with cold fuel to plug the leak, then tried to pressurize it again with helium to fix it. Both attempts failed, with NASA trying that first warm-and-chill method again to stop the leak.
A failure-free refueling process for Artemis 1 can take up to four hours, but there isn’t much room in the schedule for delays, according to NASA.
It was during the refueling process (or “refueling” as NASA calls it) that the launch controllers ran into a problem during the agency’s first launch attempt on Monday (Aug. 29). NASA called off that launch attempt when it failed to confirm that one of the SLS core stage’s four RS-25 main engines had the correct cooled temperature of minus 420 degrees Fahrenheit for launch.
The agency eventually determined that a bad sensor was causing the problem and implemented workarounds for Saturday’s launch attempt. On Saturday, NASA planned to start cooling the main engine earlier to give the SLS rocket’s engines more time to reach their target temperatures. But that process has been slowed down by the fuel leak.
NASA’s Artemis 1 mission is the first test flight for NASA’s Artemis program to return astronauts to the moon by 2025. The mission is a 37-day trip around the moon to verify that the Orion spacecraft and SLS rocket are safe for astronauts. The mission will also deploy 10 Artemis cubes en route to the moon and conduct a series of experiments to measure the astronaut experience on the Orion spacecraft.
Artemis 1 is scheduled to return to Earth on October 11 with a Pacific Ocean landing off the coast of California. If all goes well, NASA aims to launch a crew around the moon on the Artemis 2 mission in 2024, followed by the Artemis 3 manned moon landing in 2025.
Editor’s Note: This story, originally posted at 7 a.m. ET, has been updated to detail the fuel leak NASA is trying to stop on the SLS rocket. Follow our Artemis 1 mission live updates page for the latest news on the Artemis 1 mission. Visit Space.com for live webcast.