NASA announces third launch attempt date for its 'mega moon rocket'

The rollout began on Thursday (March 17) at 5:47 p.m. EDT. — NASA's rocket is the most powerful ever built.

(Image credit: NASA's Exploration Ground Systems)

NASA’s "mega moon rocket" is now scheduled to make its third liftoff attempt on Sept. 27, the US space agency has announced.

The Artemis 1 rocket is made up of the six-person Orion capsule perched atop the 30-story Space Launch System (SLS) — dubbed the "mega moon rocket" — and was initially scheduled to embark on its maiden voyage to the moon and back on Aug. 29.

But technical difficulties foiled the rocket’s first two attempts at liftoff. NASA scrubbed the rocket's first attempt because engineers were unable to cool one of the rocket's four core stage RS-25 engines down to a safe temperature in time for liftoff. The agency announced that it had fixed the problem, which it blamed on a faulty temperature sensor. Then, during the rocket’s second attempt, an alarm sounded as the craft was being loaded with its supercooled liquid hydrogen fuel, alerting engineers to a gap in the seal of one of the rocket's engines. Engineers tried and failed to plug the leak three times, NASA said.

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NASA said that the leak was at a "quick disconnect" where the SLS core stage met the fuel line from the rocket's mobile launch tower, which the agency fixed by replacing two seals at the leak point. The U.S. space agency says the earliest launch opportunity will be Sept. 27, with a backup opportunity on Oct. 2. NASA engineers plan to demonstrate the leak is patched by conducting a test to pump propellant into the craft on Sept. 17.

"The updated dates represent careful consideration of multiple logistical topics, including the additional value of having more time to prepare for the cryogenic demonstration test, and subsequently more time to prepare for the launch," NASA officials wrote in a blog post announcing the new launch date. "The dates also allow managers to ensure teams have enough rest and to replenish supplies of cryogenic propellants."

When Orion comes back, it is set to return hotter and faster than any space vehicle ever has, heating up to 5,000 degrees Fahrenheit (2,800 degrees Celsius) as it enters Earth's atmosphere at 32 times the speed of sound. This will put the capsule's ablative heat shield to the test, which, alongside the craft's parachute, will use air friction to slow Orion down to just 20 mph (32.2 km/h), after which it should plop down safely in the Pacific Ocean off the coast of Baja California, Mexico, ready for retrieval.

"This time we're going not just to touchdown [on the Moon] and leave after a few hours or a few days — we're going back to learn, to live, to work, to explore, to determine is there water; therefore on the [moon's] south pole that would mean we have rocket fuel, we have a gas station up there," Nelson said. "This time we're going to learn how to live in that hostile environment for long periods of time, all with the purpose that we're going to Mars."

Ben Turner is a U.K. based writer and editor at Live Science. He covers physics and astronomy, tech and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.