New Horizons: Pre-launch, launch and main cruise, Pluto and the Kuiper belt |
New Horizons: Pre-launch, launch and main cruise, Pluto and the Kuiper belt |
Feb 8 2005, 02:09 PM
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Member Group: Members Posts: 133 Joined: 29-January 05 Member No.: 161 |
Yes it's happening after all these years, the mission to the last planet!
And maybe to celebrate the confirmation of budget, NASA approval preparations and the fueling of the RTG (radioisotope thermoelectric generator), there is an updated web site at http://pluto.jhuapl.edu/ Launch will be January 2006 with arrival at the Pluto Charon system July 2015 (mark your calender!) and then on through the Kuiper belt during 2016-2020 and beyond. 20.8-centimeter telescope for 100m resolution at closest approach IR/UV spectrometers 2 x 8GB data recorders data rate: 768 bps (sic) to 70m DSN 465kg including fuel $650m 336 days to launch -------------------- |
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Nov 6 2005, 02:56 PM
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#2
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Senior Member Group: Members Posts: 1276 Joined: 25-November 04 Member No.: 114 |
QUOTE New Horizons would fly 3 to 4 times closer to Jupiter than the Cassini spacecraft, coming within 31.7-32.4 Jupiter radii of the large planet." That puts it just outside Callisto orbit? Did I figure that out right? |
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Nov 6 2005, 03:24 PM
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#3
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
QUOTE (Decepticon @ Nov 6 2005, 04:56 PM) Yep, Callisto orbits at a distance of about 26 Jupiter radii. The sooner the spacecraft launches in the launch window, the closer it will get to Jupiter and proportionally faster to Pluto. -------------------- |
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Nov 7 2005, 01:46 AM
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#4
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
QUOTE (ugordan @ Nov 6 2005, 08:24 AM) Yep, Callisto orbits at a distance of about 26 Jupiter radii. The sooner the spacecraft launches in the launch window, the closer it will get to Jupiter and proportionally faster to Pluto. Of course, this means that NH may fly within 6 or so Jr of Callisto, if the timing is right -- I hope it is! Ganymede could also be favorable positioned. For Io and Europa, the margin of difference is less. I doubt if an opportunistic Callisto flyby is worth tweaking any mission constraints over, although with such a long lag between Jupiter and Pluto flybys, I would guess that it would be possible in principle to time the Jupiter encounter as desired, then tweak Pluto arrival quite easily in the years to come. But that propellant budget could buy us a KBO or not post-Pluto, and it would end up being a poor tradeoff if a KBO were missed so that a so-so Callisto image sequence could be obtained! |
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Nov 7 2005, 11:22 AM
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#5
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
QUOTE (JRehling @ Nov 7 2005, 03:46 AM) I doubt if an opportunistic Callisto flyby is worth tweaking any mission constraints over, although with such a long lag between Jupiter and Pluto flybys, I would guess that it would be possible in principle to time the Jupiter encounter as desired, then tweak Pluto arrival quite easily in the years to come. But that propellant budget could buy us a KBO or not post-Pluto, and it would end up being a poor tradeoff if a KBO were missed so that a so-so Callisto image sequence could be obtained! I don't think timing a Callisto nontargeted flyby would be much of an issue at all. Callisto's orbital period is 16 days and the arrangement between Jupiter and Pluto varies slowly on a timescale of +/- 8 days (which is enough to optimize for a closest approach to Callisto for the worst case scenario). The only difference would be in the actual Jupiter C/A, that would only be changed by I guess a few tens of thousands of km yet in return it would bring Callisto at an optimal point in its orbit to cut down C/A distance from millions to a few hundred thousand km. -------------------- |
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Nov 7 2005, 05:40 PM
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#6
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Member Group: Members Posts: 701 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
QUOTE (ugordan @ Nov 7 2005, 11:22 AM) I don't think timing a Callisto nontargeted flyby would be much of an issue at all. Callisto's orbital period is 16 days and the arrangement between Jupiter and Pluto varies slowly on a timescale of +/- 8 days (which is enough to optimize for a closest approach to Callisto for the worst case scenario). The only difference would be in the actual Jupiter C/A, that would only be changed by I guess a few tens of thousands of km yet in return it would bring Callisto at an optimal point in its orbit to cut down C/A distance from millions to a few hundred thousand km. Sorry, but we won't be able to adjust the Jupiter flyby timing to optimize the view of the moons- we'll take what we can get. We can't afford the fuel it would take to slow down or speed up to catch Callisto, for example. As soon as we launch we will know our Jupiter flyby date and thus the flyby geometry for the moons, and as I remember no launch date gives us a really close look at Callisto. However, despite the geometry limitations, we'll be doing our utmost to maximize the science return from Jupiter and its moons. Our other major constraints will be our limited data storage capacity (which is designed for a quick flyby of little Pluto, not an extended flyby of giant Jupiter), and the fact that our cameras are designed to work at Pluto's dim illumination levels and thus will tend to give overexposed images at Jupiter- our best images of Io, for instance, will probably be taken in Jupiter shine, not sunshine! To answer Rob Pinnegar's question, we've been checking for close flybys of any of the outer moons, and we might get a couple of pixels on the largest ones. Nothing too spectacular though. |
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Nov 7 2005, 06:54 PM
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#7
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
QUOTE (john_s @ Nov 7 2005, 07:40 PM) Sorry, but we won't be able to adjust the Jupiter flyby timing to optimize the view of the moons- we'll take what we can get. We can't afford the fuel it would take to slow down or speed up to catch Callisto, for example. As soon as we launch we will know our Jupiter flyby date and thus the flyby geometry for the moons, and as I remember no launch date gives us a really close look at Callisto. That's a shame, but I guess any science at Jupiter is just a bonus. QUOTE Our other major constraints will be our limited data storage capacity (which is designed for a quick flyby of little Pluto, not an extended flyby of giant Jupiter), and the fact that our cameras are designed to work at Pluto's dim illumination levels and thus will tend to give overexposed images at Jupiter- our best images of Io, for instance, will probably be taken in Jupiter shine, not sunshine! I understand that the S/C has massive storage space compared to recent missions. Just what telemetry rate do you expect at Jupiter, something on the order of 115 kbps? I had a hunch illumination at Jupiter could be an issue, I didn't believe it would be a major one. Also, how do you plan to image Io in Jupiter-shine, while the Sun overexposes the daylight side? Those would have to be outbound, high phase observations? -------------------- |
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Nov 7 2005, 08:40 PM
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#8
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Member Group: Members Posts: 701 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
QUOTE (ugordan @ Nov 7 2005, 06:54 PM) I understand that the S/C has massive storage space compared to recent missions. Just what telemetry rate do you expect at Jupiter, something on the order of 115 kbps? I had a hunch illumination at Jupiter could be an issue, I didn't believe it would be a major one. Also, how do you plan to image Io in Jupiter-shine, while the Sun overexposes the daylight side? Those would have to be outbound, high phase observations? That's right, we'll look at Io in Jupiter shine at high phase and put up with an overexposed sunlit crescent. The data rate from Jupiter isn't our limiting factor on data storage, it's more to do with the complexity of managing our memory which means that we can only fill up one 32 Gbit section of the solid-state recorder once during the flyby. Plus we won't be able to crop our images before storing them, so to image a 100-pixel-wide Galilean satellite with our color camera we will need to store the full 4000-pixel width of our CCD array. |
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Nov 9 2005, 03:16 PM
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#9
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
QUOTE (john_s @ Nov 7 2005, 10:40 PM) The data rate from Jupiter isn't our limiting factor on data storage, it's more to do with the complexity of managing our memory which means that we can only fill up one 32 Gbit section of the solid-state recorder once during the flyby. Plus we won't be able to crop our images before storing them, so to image a 100-pixel-wide Galilean satellite with our color camera we will need to store the full 4000-pixel width of our CCD array. Didn't you devise any smarter lossless image compression algorithm that would know black space when it sees it? IMO, that sort of thing was feasible probably even in the days Cassini was designed (as opposed to the lossless-although-line-truncating algorithm implemented) let alone today. Sort of like dividing the frame conceptually into two categories: empty space (which would be all low intensity background noise) and actual useful data. The encoding tables could be optimized for two extreme cases then. I read about even more advanced concepts, actually analyzing images taken through different filters and transmitting back only differences, this would be perfect for pushbroom cameras as there wouldn't be any alignment issues due to spacecraft attitude changes. Hm, maybe I'm getting a wee bit too technical here -------------------- |
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Nov 13 2005, 03:21 AM
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Senior Member Group: Members Posts: 2517 Joined: 13-September 05 Member No.: 497 |
QUOTE (ugordan @ Nov 9 2005, 07:16 AM) Didn't you devise any smarter lossless image compression algorithm that would know black space when it sees it? If you are using a first-difference-based lossless compressor, you can get this for free depending on what encoding table you use and what your black-space noise level is. For example, on MGS/MOC, we use a table that compresses black space 8:1, and we occasionally use this for star calibration images. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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