Monday’s earlier attempt to launch the 322-foot-long (98-meter) Space Launch System rocket, the most powerful ever built by NASA, was also troubled by hydrogen leaks, albeit smaller ones. This was in addition to the leaks identified during countdown exercises earlier in the year. After the latest failure, mission managers decided to pull the rocket off the pad and into the hangar for further repairs and system updates. Some of the work and testing may take place on the pad before the rocket is moved. With a two-week launch downtime approaching in just a few days, the rocket is now grounded until the end of this month or even October. NASA will work around a high-priority SpaceX astronaut flight to the International Space Station scheduled for early October. NASA Administrator Bill Nelson stressed that safety is the top priority, especially on a test flight like this where everyone wants to verify the rocket’s systems “before we put four people on top of it.” “Just remember: We’re not going to launch until it’s right,” he said. NASA already waited years to send the crew capsule atop the rocket around the moon. If the six-week demonstration is successful, astronauts could fly around the moon in 2024 and land on it in 2025. Humans last walked on the moon 50 years ago. Launch Manager Charlie Blackwell-Thompson and her team had just begun loading nearly 1 million gallons of fuel into the Space Launch System rocket at dawn when the large leak appeared in the engine compartment at the bottom. Ground controllers tried to plug it the same way they handled previous leaks: by stopping and restarting the flow of ultra-cold liquid hydrogen in hopes of closing the gap around a seal in the supply line. They tried it twice, actually, and also shot helium through the line. But the leak continued. Blackwell-Thompson finally stopped the countdown after three to four hours of futile attempts. Mission Director Mike Sarafin told reporters it was too early to say what caused the leak, but it may have been due to an inadvertent overpressurization of the hydrogen line earlier in the morning when commands were sent to the wrong valve. “This was not a manageable spill,” Sarafin said. During Monday’s attempt, a series of smaller, unrelated hydrogen leaks appeared on the rocket. Technicians tightened the components over the next few days, but Blackwell-Thompson had warned she wouldn’t know if everything was tight until Saturday’s feed. Hydrogen molecules are extremely small – the smallest there are – and even the tiniest gap or crevice can provide a way out. NASA’s space shuttles, now retired, were plagued by hydrogen leaks. The New Moon rocket uses the same type of main engines. Adding to the problem on Monday, a sensor indicated that one of the rocket’s four engines was too hot, but engineers later confirmed that it was actually quite cold. The launch team planned to ignore the faulty sensor this time and rely on other instruments to ensure each main engine was properly cooled. But the countdown never got that far. Mission managers acknowledged the added risk of the engine issue as well as a separate problem: cracks in the rocket’s insulating foam. But they acknowledged that other problems – such as fuel leaks – could cause another delay. That didn’t stop thousands of people from jamming the coast hoping to see the Space Launch System rocket soar. Local authorities were expecting massive crowds due to the Labor Day weekend. The $4.1 billion test flight is the first step in NASA’s Artemis program for renewed lunar exploration, named after the twin sister of Apollo in Greek mythology. Years behind schedule and billions over budget, Artemis aims to establish a permanent human presence on the moon, with crews eventually spending weeks there at a time. It is considered training for Mars. Twelve astronauts walked on the moon during the Apollo program, the last time in 1972.
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