U.S space agency has had to postpone the launch of its new Artemis I Moon rocket for the second time in a week.
Controllers were unable to stop a hydrogen leak on the vehicle, almost from the start of Saturday’s countdown procedure.
Nasa now has another opportunity to launch the rocket on Monday or Tuesday.
After that the vehicle will have to return to its assembly building for inspection and maintenance, which will mean further delays.
The Space Launch System is the most powerful rocket ever developed by Nasa, and is designed to send astronauts and their equipment back to the lunar surface after an absence of 50 years.
Much of the SLS’s enormous thrust comes from burning almost three million litres of super-cold liquid hydrogen and oxygen in four big engines on the vehicle’s underside.
Yesterday’s attempt to despatch the Space Launch System (SLS) rocket had been scheduled for the start of a two-hour window beginning at 14:17 local time (19:17 BST; 18:17 GMT).
The 100m-tall vehicle’s objective is to hurl a human-rated capsule, called Orion, in the direction of the Moon, and something that hasn’t happened since Project Apollo ended in 1972.