Saturday’s planned four-mile journey on the crawler-transporter-2 will take up to 12 hours. Once there, engineers will begin a series of launch pad preparations, including connecting ground support equipment such as electrical lines, fuel environmental control system ducts, and cryogenic propellant feeds.
At the end of January, Nasa will conduct what it describes as a wet dress rehearsal, which is a prelaunch test to fuel the rocket. If there are any issues, Nasa may roll back SLS and Orion to the Vehicle Assembly Building for additional work ahead of launch.
But if all systems are go, the earliest possible launch date would be Friday 6 February. As well as the rocket being ready, the Moon has to be in the right place too, so successive launch windows are selected accordingly.
In practice, this means one week at the beginning of each month during which the rocket is pointed in the right direction followed by three weeks where there are no launch opportunities.
The potential launch dates are therefore:
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6, 7, 8, 10 and 11 February
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6, 7, 8, 9 and 11 March, and
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1, 3, 4, 5 and 6 April
