The countdown clock for the launch of NASA's most powerful rocket was put on hold at T-40 minutes as the hydrogen team discussed the plans with Artemis 1 launch director.
“The launch of Artemis I is no longer happening today as teams work through an issue with an engine bleed. Teams will continue to gather data, and we will keep you posted on the timing of the next launch attempt," the US space agency wrote on Twitter.
Alternative dates for launch of the Artemis 1 mission, an uncrewed flight around the Moon as part of an ambitious program to eventually go to Mars, are 2 and 5 September.
Official confirmation of the delay came after the space agency spent the early morning hours investigating issues including a potential crack in material in the main body of the rocket as well as a possible temperature issue with one of the main engines. Those came after engineers examined and resolved a suspected leak affecting the hydrogen tanking process.
The countdown clock was halted for around 40 minutes before the targetted launch time of 8:33 am EDT (1233 GMT), as the 32-story-tall, two-stage Space Launch System (SLS) rocket and its Orion crew capsule awaited liftoff from the Kennedy Space Center in Cape Canaveral, Florida.
NASA cited a problem detected on one of the rocket's main engines, after launch teams had begun filling the rocket's core fuel tanks with super-cooled liquid oxygen and hydrogen propellants.
The US space agency did not give a new launch date but said its first available backup launch opportunity was set for 2 September.
All about Artemis I mission
The uncrewed mission, known as Artemis I, will be the first major flight in NASA’s ambitious plan to send the first woman and the first person of colour to the lunar surface as early as 2025.
Artemis I is aimed at testing out the SLS, made by Boeing Co, and a new deep-space crew capsule called Orion that was developed by Lockheed Martin Corp.
When Artemis I does launch, SLS will be sending Orion on a 42-day mission, along with a host of payloads and sensors to track the journey. The capsule is tasked with inserting itself into lunar orbit and entering deep space before return to Earth in the Pacific Ocean off San Diego.
The Space Launch System already is more than five years behind schedule. It has been in development for roughly a decade, slowed by a myriad of delays and cost overruns. Development costs of the program have soared from an original $7 billion to about $23 billion, according to an estimate by the Planetary Society.
If successful, the Artemis programme – named for the twin sister of the god Apollo in Greek mythology – will see the return of people to the lunar surface for the first time in 50 years. No one has visited the moon since Apollo 17 in December 1972.
