NASA's new moon rocket sprouted more fuel leaks Wednesday in a test ahead of a possible launch attempt next week, but engineers managed to get them down to acceptable levels.
There was no immediate word on whether NASA would try for a liftoff Tuesday given the sporadic nature of the hydrogen leaks, which have bedeviled the launch team for months.
"Leaving a lot of folks scratching their heads on this one," said Launch Control's Derrol Nail.
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The daylong demo had barely begun when hazardous hydrogen fuel began escaping at the same place and same time as before, despite new seals and other repairs. Engineers halted the flow and warmed the lines in hopes of plugging the leak, and proceeded with the test. But the leak persisted before dropping to acceptable levels. Hours later, another leak cropped up elsewhere.
Nail said all test objectives were met. But managers need to review the results before determining whether the 98-metre rocket is ready for its first test flight, a lunar-orbiting mission with mannequins instead of astronauts.
Hydrogen leaks spoiled the first two launch attempts, as well as earlier countdown tests. So much hydrogen escaped during the countdown earlier this month that it exceeded NASA's limit by more than double. Wednesday's leak almost got that big again.
After hours of fits and starts, NASA finally managed to load nearly 4 million litres of fuel into the rocket. It was unclear whether the earlier gusher would nix a Tuesday launch attempt. In a separate matter, NASA still needs the U.S. Space Force to extend the certification of on-board batteries that are part of the flight safety system.
After the September 3 launch delay, NASA replaced two seals in the leaky line. One seal had a tiny indentation; it measured a mere one-hundredth of an inch.
"Now that doesn't sound like a lot, but again we're dealing with hydrogen," the smallest element on the periodic table, said mission manager Mike Sarafin.
NASA also altered the fuelling process, easing slowly into the loading of the super-cold liquid hydrogen and oxygen. After Wednesday's big leak appeared, the launch team moved even more slowly to subject the plumbing to even less stress.
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Once launched, the crew capsule atop the rocket will be the first to orbit the moon in 50 years. The USD 4.1 billion mission should last more than five weeks, ending with a splashdown in the Pacific. Astronauts would climb aboard for the second test flight, dashing around the moon in 2024. The third mission, targeted for 2025, would see a pair of astronauts actually landing on the moon.
NASA's Space Launch System rocket is more powerful than the Saturn V rocket that sent Apollo astronauts to the moon during the late 1960s and early 1970s. The engines and boosters are carryovers from the now retired space shuttles. Just like now, NASA struggled with elusive hydrogen leaks during the shuttle era, especially during the early 1990s.