Two previous attempts were scrapped after the giant Space Launch System rocket experienced technical glitches including a fuel leak.

“The 23rd is a 6.47am window open for 80 minutes, and the 27th is an 11.37am window with a 70-minute duration,” said Free, associate administrator for the agency’s exploration systems development directorate.

The dates were chosen to avoid a conflict with the Dart (Double Asteroid Redirection Test), in which a probe is set to strike an asteroid on Sept 26.

The launch dates depend, however, on Nasa receiving a special waiver to avoid having to retest batteries on an emergency flight system that is used to destroy the rocket if it strays from its designated range to a populated area.

If it does not receive the waiver, the rocket will have to be wheeled back to its assembly building, pushing the timeline back several weeks.

Mike Bolger, exploration ground systems manager, added that teams were working to replace seals to fix the hydrogen leak issue – work that could be completed by the end of today, which would pave the way for a tanking test on Sept 17.

The Artemis 1 space mission hopes to test the SLS as well as the unmanned Orion capsule that sits atop, in preparation for future moon-bound journeys with humans aboard.