Nasa officially postpones rocket launch to Moon due to fuel leak

Nasa’s new moon rocket sprang another dangerous fuel leak on Saturday, 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 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.

For the second time this week, the launch team began loading nearly 1 million gallons of fuel into the rocket.

As the sun rose, an over-pressure alarm sounded and the tanking operation was briefly halted, but no damage occurred and the effort resumed. But minutes later, hydrogen fuel began leaking from the engine section at the bottom of the rocket. Nasa halted the operation, while engineers scrambled to plug what was believed to be a gap around a seal in the supply line.

Nasa wants to send the crew capsule atop the rocket around the moon, pushing it to the limit before astronauts get on the next flight. 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 Kennedy Space Center, especially toward the end of the two-hour afternoon launch window.

Even more of a problem on Monday, a sensor indicated one of the rocket's four engines was too warm, but engineers later verified it actually was cold 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 frigid as the liquid hydrogen fuel flowing into them at minus-250 degrees Celsius. If not, the resulting damage could lead to an abrupt engine shutdown and aborted flight.

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