Nasa called off its latest attempt to launch the groundbreaking Artemis 1 moon rocket on Saturday after failing to stem a fuel leak discovered during tanking. It was the second time in five days that technical issues had kept the spacecraft on the launchpad.
Mission managers waited until the late in the countdown to scrub the liftoff after the failure of several workarounds to try to stem the leak of liquid hydrogen into the core stage of the Space Launch System (SLS) rocket.
It was not immediately clear if the US space agency would be able to make launchpad fixes in time to meet its next backup launch date of Monday, or if Artemis will need to roll back to the vehicle assembly building for more substantial repairs.
Such a scenario would further delay the maiden test flight of humanity’s first crew-capable moon mission in 50 years until at least the middle of this month.
Nasa’s Artemis launch director Charlie Blackwell-Thompson agreed with a recommendation of the fuel systems team and called off the launch at 11.20am local time (4.20pm BT), with almost 2 hours and 29 minutes left in the countdown.
The fuel leak, which became apparent during early morning tanking of 2.76m litres (730,000 gallons) of liquid hydrogen and oxygen, is separate from the engine cooling issue that forced the postponement of the first launch attempt last Monday. Officials said they had identified that problem as a faulty sensor rather than an issue with the cooling system or engine itself.
But the latest setback will be a disappointment for the agency keen to showcase the progress it has made in returning humans to the lunar surface for the first time since the Apollo 17 mission of 1972.
This 38-day mission, to 40,000 miles beyond the moon and back, is uncrewed, but must be successful before astronauts can board a second test flight planned for 2024, then a moon landing on Artemis III currently scheduled for no earlier than late 2025.
Upwards of a quarter-million spectators had packed the beaches and causeways of Florida’s space coast on the Labor Day holiday weekend, eager to witness a moment of history.
Bill Nelson, the head of Nasa, had cautioned this was a test mission, and that delays were part of the process. “This is an extremely complicated machine and system. Millions of parts,” he told told reporters at Cape Canaveral.
Mission managers indicated the liquid hydrogen leak was inside one of the four RS-25 engines on SLS, which will become the most powerful rocket ever to leave Earth when it finally launches.
The engines are recycled from the long-retired space shuttle programme, and provide 15% more thrust than the Saturn V rockets of the Apollo era.