How far will NH pass by Pluto?, - and will it be possible to effect a meaningful course change? |
How far will NH pass by Pluto?, - and will it be possible to effect a meaningful course change? |
Guest_Oersted_* |
Apr 16 2008, 02:16 PM
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Guests |
So, from what I gather, NH will pass by Pluto at a speed of around 14 km/s. I know it won't be able to slow down in any way, and will continue into deep space afterwards, but is a substantial course change envisaged at Pluto, or will it fly by so far away that the course change will be negligible?
I realise that the instruments must be optimised for a pass at a certain distance, but what distance is that and could it possible by reduced with no ill effects? It would be mindblowing if a low pass over Pluto could be planned so that NH will fly close by Charon as well, wouldn't it? - Or maybe even - to go really out on a limb - a few high-speed figure 8's around both bodies, before the probe continues on its merry way. Would that even be physically possible? At least I'm not suggesting aero-braking if Pluto turns out to have a tenuous atmosphere. |
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Apr 17 2008, 10:44 AM
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Rover Driver Group: Members Posts: 1015 Joined: 4-March 04 Member No.: 47 |
I'm not sure what an S-shaped orbit would be, but there are no stable 3-body orbits except for L4 and L5. I know that the proof of this starts with Hamiltonians and Lagrangians (or at least I think it does) but I'm not able to work it out myself. However, I remember Feynman telling it to my freshman class at Caltech, and I suspect he knew what he was talking about. :-) --Greg Things seem to have moved on since Feynman's days...check this out! http://www.ams.org/notices/200105/200105-body-ps.html And of course spiraling orbits occur all the time if you have atmospheric drag (not stable though!). Fascinating subject, and unfortunately off topic Physics forum used to have a celestial mechanics bit, but I think they changed the format a bit. |
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Apr 18 2008, 04:18 PM
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Senior Member Group: Members Posts: 1018 Joined: 29-November 05 From: Seattle, WA, USA Member No.: 590 |
Things seem to have moved on since Feynman's days...check this out! http://www.ams.org/notices/200105/200105-body-ps.html That IS impressive! Had not seen that at all. But it's not a figure-8 orbit around two objects; it's three equal bodies in a mutual figure-8 pattern, so it doesn't apply to the original question: Or maybe even - to go really out on a limb - a few high-speed figure 8's around both bodies, before the probe continues on its merry way. Would that even be physically possible? I suppose the cleanest answer would have been to say "NH is moving so fast, and Pluto and Charon are so small, that the only possible orbits for NH -- even using the engines -- are variations on a nearly straight line." As Alan Stern said two years ago, a one-degree deflection is the most anyone thinks we can get. And, certainly, as Apollo 8 showed, a figure-8 trajectory is possible, if you only need to do it one time. But this puts a fairly strict upper bound on the velocity of the vehicle -- it can't have more than a very small hyperbolic excess velocity with respect to either body. Space probes aren't like cars; NASA can't just downshift into the turn. :-) --Greg |
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