That's when their spacecraft, which launched to Mars in August, will finally arrive on the Red Planet.

Do you say "The rocket launched to the Moon" or "The rocket was launched to the Moon"?

I think the latter is correct, so we need 'was' in the original sentence. What do you think?

I agree with you, but it doesn't cause me any discomfort to hear "The rocket launched to the moon"
Both correct:
intransitive verb
1 a : to spring forward : take off <a junco had launched off a chinquapin twig -- W.V.T.Clark> <the catapult snagged and the plane overturned before it could launch>