Mission managers waited until the end of the countdown to clear the launch after several solutions to try to stop a leak of liquid hydrogen in the Space Launch System (SLS) rocket’s core stage failed. It was not immediately clear whether the US space agency would be able to make repairs to the launch site in time to meet Monday’s next backup launch date, or whether Artemis would need to return to the vehicle assembly building for more substantial repairs. Such a scenario would further delay the maiden test flight of humanity’s first manned moon mission in 50 years until at least the middle of this month. Nasa’s Artemis launch manager Charlie Blackwell-Thompson agreed with a recommendation from the fuel systems team and aborted the launch at 11.20am. local time (4.20pm BT), with almost 2 hours and 29 minutes remaining in the countdown. The fuel leak, which became apparent during the 2.76 m liter (730,000 gallon) tank of liquid hydrogen and oxygen early in the morning, is separate from the engine cooling problem that forced the postponement of the first launch attempt last Monday. Officials said they had traced that problem to a faulty sensor rather than a problem with the cooling system or the engine itself. But the latest setback will be a disappointment for the agency, which wants to showcase the progress it has made in returning humans to the lunar surface for the first time since Apollo 17 in 1972. This 38-day mission, 40,000 miles past the moon and back, is uncrewed but must be successful before astronauts can board a second test flight planned for 2024 and then a landing on moon on Artemis III scheduled for no earlier than late 2025. More than a quarter of a million spectators packed the beaches and trails of Florida’s Space Coast over the Labor Day holiday weekend, eager to witness a moment of history. Bill Nelson, the head of NASA, had warned that it was a test mission and that delays were part of the process. “This is an extremely complex machine and system. Millions of parts,” he told reporters in Cape Canaveral. Mission managers said the liquid hydrogen leak was inside one of the SLS’s four RS-25 engines, which will become the most powerful rocket ever to leave Earth when it finally launches. The engines are recycled from the long-defunct space shuttle program and provide 15 percent more thrust than Apollo-era Saturn V rockets.
