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> Since the orbital dynamics are very well understood and there really isn't anything that can affect the motion of the spacecraft other than engine burns This
by bufferoverflow 7y ago
> Since the orbital dynamics are very well understood and there really isn't anything that can affect the motion of the spacecraft other than engine burns
This is wrong.
1) Atmospheric drag (unless you're in really high orbits)
2) Wind
3) Uneven gravitational field. Our planet is not a perfect sphere. The moon is even less so.
4) Solar pressure (though very minor and kinda evens out in orbit).
- beering 7y agoWhich of these can't you calculate ahead of the launch? Numbers 1, 3, and 4 seem like you could calculate it ahead of time. And maybe number 2 as well, if you do it relatively close to launch time.
- nategri 7y agoThey use models. No model is perfect, they all have uncertainties.
- entropicdrifter 7y agoWhich is why they use pilots too
- sheinsheish 7y agoI wonder how come none of you geniuses don’t already work for NASA
- magduf 7y agoI'll name two things: 1) Government pay 2) Government shutdowns But regardless, this was a Boeing spacecraft; it wasn't built by NASA (NASA generally does systems engineering; contractors build things like this).
- dgoodell 7y agoA government shutdown is a basically surprise paid vacation, as long as you have enough cash to skip a couple paychecks.
- hgoel 7y agoThe unevenness of the gravitational field on Earth is for the most part ignorable. It isn't like maneuvers are precise enough that one could account for it in the calculations anyway. Space is empty enough and engines imprecise enough that for orbital stuff you have enough margins to correctly predict and plan a trajectory ahead of time, and just do correction burns later if necessary. On the Moon the gravitational field is indeed uneven enough to matter, but exactly one orbiter really cares about it (LRO iirc has a specific orbit where the unevenness mostly cancels out), most simply rely on occasional station keeping burns.