NASA’s new moon rocket sprang another dangerous fuel leak on September 3, 2022, forcing launch controllers to call off their second attempt to send a crew capsule into lunar orbit with test dummies.
The first attempt earlier in the week was also marred by escaping hydrogen, but those leaks were elsewhere on the 322-foot (98-metre) rocket, the most powerful ever built by NASA.
Launch director Charlie Blackwell-Thompson and her team tried to plug Saturday’s leak the way they did the last time: stopping and restarting the flow of super-cold liquid hydrogen in the hopes of removing the gap around a seal in the supply line. They tried that twice, in fact, and also flushed helium through the line. But the leak persisted.
Blackwell-Thompson finally halted the countdown after three to four hours of futile effort.
Earlier, for the second time this week, the launch team began loading nearly 1 million gallons of fuel into the rocket. Monday’s attempt was halted by a bad engine sensor and leaking fuel.
As the sun rose on Saturday, an over-pressure alarm sounded and the tanking operation was briefly halted. The effort resumed after no damage was detected. But minutes later, hydrogen fuel began leaking from the engine section at the bottom of the rocket. NASA halted the operation once again, while engineers scrambled to plug what was believed to be a gap around a seal in the supply line.
The countdown clocks continued ticking for an afternoon liftoff. NASA had two hours on Saturday to get the rocket off.
NASA wants to send the crew capsule atop the rocket around the moon and push it to the limit. If the five-week demo with test dummies succeeds, astronauts could fly around the moon in 2024 and land on it in 2025. People last walked on the moon 50 years ago.
Forecasters expected generally favourable weather at the Kennedy Space Center, especially towards the end of the two-hour afternoon launch window.
On Monday, hydrogen fuel escaped from elsewhere in the rocket. Technicians had tightened up the fittings over the past week, but launch director Charlie Blackwell-Thompson had stressed that she wouldn't know whether everything was tight until Saturday's fuelling.
Even more of a problem on Monday, a sensor indicated one of the rocket's four engines was too warm, but engineers later verified that it actually was cool enough. The launch team planned to ignore the faulty sensor this time around and rely on other instruments to ensure each main engine was properly chilled.
Before igniting, the main engines need to be as cold as the liquid hydrogen fuel flowing into them at minus-420 degrees Fahrenheit (minus-250 degrees Celsius). If they are not, the resulting damage could lead to an abrupt engine shutdown and abortion of the flight.
Mission managers have acknowledged the additional risk posed by the engine issue as well as a separate problem — cracks in the rocket's insulating foam, and said other problems, such as fuel leaks, could prompt yet another delay.
Thousands thronged the coast to see the Space Launch System rocket soar on Saturday. Local authorities had expected massive crowds because of the long Labour Day holiday weekend.
The $4.1-billion test flight is the first step in NASA’s Artemis program of renewed lunar exploration, which has been named after the twin sister of Apollo in Greek mythology.
Twelve astronauts had walked on the moon during NASA’s Apollo program in 1972.
Artemis (years behind schedule and billions of dollars over budget) aims to establish a sustained human presence on the moon, with crews eventually spending weeks at a time there. It is considered a training ground for Mars.
