NASA conducted a leak test of its moon rocket in preparation for a potential launch attempt next week.
The first test flight, a simulated trip around the Moon with dummies in place of humans.
Will take place after the daylong demonstration.
Managers are looking to double check that any hydrogen leaks, which derailed the first two launches and early countdown tests
Have been fixed. Back in the beginning of the month, during the final countdown
The amount of hydrogen released was twice what NASA had previously considered safe.