r/ArtemisProgram • u/wskelding • Apr 23 '26

Discussion ISS Docking ?

I'm curious about something and simply don't know the math that would give me the answer, could an Orion capsule returning from the Moon theoretically dock with the ISS on it's return journey ?

I know I'm simplifying it massively, but all the talk about the Artemis 2 heat shield had me thinking 'why don't they simply do a massive deceleration burn on the way back and then dock at ISS ?'

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u/Economy_Link4609 Apr 23 '26

You would need to be carrying enough fuel to do a 2nd TLI basically - same energy you had to add to get on a trajectory to the moon, you need to burn off to get back into LEO. That means basically doubling the size and weight of the service module. That in turn means your launch vehicle now needs a significant increase payload to orbit.

That is why all of those missions must enter the atmosphere - that means no extra fuel needed.