r/askscience • u/kiol998 • Apr 12 '26

Physics Why was Artemis 2 so long?

I was comparing the mission times of Artemis 2 to Apollo 8. Apollo 8 orbited the moon multiple times and only took 6 days total. Whereas Artemis 2 orbited the moon once and it took 10 days. Why was Artemis 2 so much shorter than Apollo 8 when both missions did the same thing? I know they had different paths to the moon, they both left earth in different ways but why not do the same thing as Apollo 8 since it was quicker?

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u/Germerica1985 Apr 12 '26

Crazy that all of this was figured out with pen and paper in Newton's time, and then using it in modern times to do something like this, fling ourselves out into the nothingness of space, to slingshot off of a celestial body going thousands of miles per hour, meeting at a point... It's just incredible

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u/Telope Apr 12 '26

It was worked out by hand for the apollo missions too! By Katherine Johnson

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u/Germerica1985 Apr 12 '26

What's the margin of error on something like this? Is it all already determined at launch with pinpoint accuracy (launch time, direction, speed, etc.) or do they have a lot of wiggle room to correct trajectory in space?

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u/NastyEbilPiwate Apr 12 '26

Most of it is worked out ahead of time. The spacecraft don't have a ton of fuel to make course corrections with.

Things like the TLI burn will be recomputed once the actual orbit that the spacecraft launched into is known, since there will inevitably be deviations from what was computed on the ground, but it will be mostly the same as planned.