just been watching Apollo 13 the movie, paying attention to the details, I was wondering about something. When on the return to earth, they have to get a calculation on the correction burn. Houston makes a calculation and then later has to correct it, because they 'forgot' to subtract the weight of the moon-rocks they didn't bring back with them.
This made me wonder; how does Nasa calculate these things? And why could they make such an error as not to include a weight like that? Do they make all the calculations in advance, before the mission even starts and is that where the rocks are assumed in the calculations?
I'm reading up on Nasa missions at the moment, but maybe someone can explain here how they do this, just for the fun of knowing it.