Nasa has called off the launch of its big new Moon rocket – the Space Launch System (SLS).
Controllers struggled to get an engine on the 100m-tall vehicle cooled down to its correct operating temperature.
They had previously worried about what appeared to be a crack high up on the rocket but eventually determined it was merely frost build-up.
The SLS is the biggest rocket ever developed by Nasa. It will be used to send astronauts back to the Moon.
The maiden flight, part of…
