New Horizons Jupiter Encounter |
New Horizons Jupiter Encounter |
Guest_AlexBlackwell_* |
Jan 10 2007, 09:47 PM
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Guest_AlexBlackwell_* |
Mar 1 2007, 10:12 PM
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Mar 2 2007, 10:18 AM
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Newbie Group: Members Posts: 11 Joined: 13-August 05 From: Belgium Member No.: 465 |
Copy from the above link: http://pluto.jhuapl.edu/overview/piPerspec...7_image1_hr.jpg http://pluto.jhuapl.edu/overview/piPerspec...7_image2_hr.jpg The graphics illustrate the boost in speed, over time, that New Horizons gets from flying past Jupiter. |
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Mar 2 2007, 03:38 PM
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Member Group: Members Posts: 153 Joined: 14-August 06 Member No.: 1041 |
Copy from the above link: http://pluto.jhuapl.edu/overview/piPerspec...7_image1_hr.jpg http://pluto.jhuapl.edu/overview/piPerspec...7_image2_hr.jpg The graphics illustrate the boost in speed, over time, that New Horizons gets from flying past Jupiter. Alan's charts seem to agree with Emily's - placing the maximum velocity about 11 hours after closest approach. My feeble mental integrater tells me this is the period where NH's is 'hookybobbing', flirting with Jupiter's gravity to steal kinetic energy from Jupiter with no intention of giving it back. (If Jupiter appears a little bigger in the sky, blame NH - it is something like 3.2x10^-47 picometers closer Whats this MPH thing? |
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Mar 2 2007, 04:57 PM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
FYI, qualitative physics is hard to get results with and quantitative physics is just plain no fun (and in the three body situation, unsolvable), but if you'd like an existence proof that maximum velocity needn't occur at closest approach, imagine a satellite in a distant elliptical orbit around Neptune. Nereid will do. It has an orbital velocity with respect to Neptune varying from 0.4 km/s to 3.0 km/s. Neptune has an orbital velocity of 5.4 km/s.
If the node of Nereid's orbit were such that its top velocity were subtractive from the Neptune-Sun velocity, but the slowest velocity were additive, then it would be moving at 2.4 km/s WRT the Sun at closest approach to Neptune, but 5.8 km/s WRT the Sun at apoapsis. (Imagine that the apoapsis were 180 degrees away from the Sun from Neptune's perspective and that the orbit were prograde and in the ecliptic... this is a gedankenexperiment anyway.) That's a much more profound case than possible with a hyperbolic orbit (WRT the planet), but the same principle applies. The Jupiter encounter bends NH's path to be less radial. As that bending occurs, NH's great speed WRT Jupiter is added to its speed WRT the Sun. In the short run around C/A, NH will neither gain nor lose much speed WRT the Sun nor Jupiter, but the bending makes their two effects more additive than orthogonal. So it makes sense that at least on some tiny time scale the speed immediately after C/A would be greater than the speed the same interval before C/A. That's too hand-wavy, of course, to tell whether the lag would be a picosecond or a day, but maximum speed WRT the Sun should be *some* interval after C/A for all such gravity assists. Did my hands stop waving long enough for this to make sense to anyone? |
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