[420official]

The amount of things that would have to go wrong for the craft to get an accidental gravity boost and be ejected would be significant.

I feel like the original claim paints the whole thing as on a knife edge and barely achieved by virtue of not making a single mistake. In today's age with so many moon landing deniers and worse I feel like we should be specific about where the actual dangers challenges and unknowns there were here. In reality, the orbital mechanics are one of the simplest parts of the entire problem, at least when we're talking about a moon flyby

[dgfl]

Yes, this is a fair point. I agree that orbital mechanics is trivially easy compared to everything else. The chances of a math mistake in particular are null, these trajectories have all been calculated years in advance.

[WalterBright]

The lumpiness of the moon's gravity is not well mapped out.

[accrual]

It is now better mapped after the GRAIL mission: https://en.wikipedia.org/wiki/Gravity_Recovery_and_Interior_...

[WalterBright]

The moon's gravity turns out to be "lumpy" because its density is not constant. This was detected by the Apollo missions and caused them to make errors in orbit calculations. This source of error could have influenced the flyby.