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New Horizons: Pre-launch, launch and main cruise, Pluto and the Kuiper belt
djellison
post Nov 7 2005, 03:36 PM
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As I understand it - the RTG is a mass model - i.e. it's not the real thing, it's just there to act the same - and it might well be a few years old, perhaps borrowed from the spares-cupboard of a past mission?

Doug
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odave
post Nov 7 2005, 04:32 PM
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Let's hope they remember to put the real one on before launch laugh.gif

Now THAT would be a "D'OH" moment!


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ugordan
post Nov 7 2005, 05:21 PM
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QUOTE (odave @ Nov 7 2005, 06:32 PM)
Let's hope they remember to put the real one on before launch laugh.gif

Now THAT would be a "D'OH" moment!
*

Forgetting to take off one of the instrument covers that just scream "Remove before flight" would come in as a close second tongue.gif


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john_s
post Nov 7 2005, 05:40 PM
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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.
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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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ugordan
post Nov 7 2005, 06:54 PM
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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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john_s
post Nov 7 2005, 08:40 PM
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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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imran
post Nov 7 2005, 11:33 PM
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A pretty in-depth article in the John Hopkins Magazine on New Horizons and how the mission concept turned into reality.

http://www.jhu.edu/~jhumag/1105web/pluto.html
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Comga
post Nov 8 2005, 04:20 AM
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QUOTE (john_s @ Nov 7 2005, 02:40 PM)
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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Would it be too picky and petty to remind John that the CCD array is 5000 pixels wide? wink.gif Of course, that just makes his point that much stronger.
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tfisher
post Nov 8 2005, 06:35 PM
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QUOTE (Comga @ Nov 8 2005, 12:20 AM)
Would it be too picky and petty to remind John that the CCD array is 5000 pixels wide?  wink.gif  Of course, that just makes his point that much stronger.
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I've also seen the number 5024 pixels somewhere. Unfortunately the "public consumption" websites are pretty coy about such details. (Is it because they are afraid people will compare these numbers with their digital cameras and wonder why they have more megapixels in their hands than the fancy space probe?) Anyway, here is what I can glean about resolution. Maybe someone can confirm or correct these numbers?

Ralph: 5000x(arbitrary) pixels at 12bpp. For science images, this will sweep across a target pushbroom style (time delayed imaging or TDI in modern parlance) taking data either in 4 color bands (red, blue, near IR, methane) simultaneously or through a panchromatic (clear) filter. There is also a 5000x128 pixel framing mode, mainly for navigational use. It is sensitive to visable and near IR light from about 400 to 1000 nm.

Leisa: 256x(arbitrary) pixels with 256 spectral channels at 12bpp. This also images in TDI mode. This is sensitive to IR from about 1000 to 2500 nm.

Alice: 32x1 pixels with 1024 spectral channels at 16bpp. (maybe possible to produce an image by slewing?). It either works in "histogram" mode summing hits at each location on the detector or "pixel list" mode producing a list photon hits at 4ms cadence. This is sensitive to UV from 50 to 185 nm.

Lorri: 1024x1024 pixels at 12bpp. This is works in framing mode. It is sensitive to visible light (very sensitive in fact: out at pluto exposure time is around 1/10 of a second!) and has a field of view of 0.29 degrees for long telephoto opportunities. It also has a binned 256x256 pixel mode for faint object imaging.
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JRehling
post Nov 8 2005, 08:53 PM
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QUOTE (john_s @ Nov 7 2005, 10:40 AM)
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.
*


If an ideal Callisto flyby had taken place, it would have been about 40 times the planned Pluto flyby C/A (actually, eerily close to 40.00 times, as I did the math...). An ideal Ganymede flyby would have been about 3 times farther than that, so if a pixel is 50 m at Pluto, it could be as good as 600 m at Ganymede. Murphy's Law may put both Ganymede and Callisto on the far side of Jupiter at the flyby... we'll see! But the light sensitivity sounds like a showstopper for great visible-wavelength imaging anyway. The best hope may be that spectroscopy can get a bit higher spatial resolution at Ganymede and Callisto to get readings on distinct terrain types.

Jupiter, of course, will fill the frames rather nicely even from 32 Jr. The spectroscopy of Jupiter itself will be nice to see.
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john_s
post Nov 8 2005, 09:02 PM
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QUOTE (tfisher @ Nov 8 2005, 06:35 PM)
I've also seen the number 5024 pixels somewhere.  Unfortunately the "public consumption" websites are pretty coy about such details.  (Is it because they are afraid people will compare these numbers with their digital cameras and wonder why they have more megapixels in their hands than the fancy space probe?)  Anyway, here is what I can glean about resolution.  Maybe someone can confirm or correct these numbers?


*


The New Horizons website does have a table that gives the details for the instrument payload. Your summary is pretty much correct! Yes, I goofed on the MVIC detector length- 5000 pixels is the correct number.
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Decepticon
post Nov 8 2005, 11:21 PM
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Will this probe carry a gold disk of some kind? Ala Voyager/Pioneer
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punkboi
post Nov 9 2005, 12:20 AM
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QUOTE (Decepticon @ Nov 8 2005, 04:21 PM)
Will this probe carry a gold disk of some kind? Ala Voyager/Pioneer
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It will be carrying a compact disc bearing the names of people who submitted 'em through the New Horizons website


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edstrick
post Nov 9 2005, 07:47 AM
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I suspect some of the most valuable PICTURES during the Jupiter flyby will be of the moons in Jupiter shadow. Io's multi-colored aurora are spectacular, but Galileo's images are pretty horrible due to radiation noise and low light levels. I don't think there was any direct imaging system detections of airglows or hypothetical irradiation induced "iceglows" at the other satellites. Timing of the flyby may randomly allow an observation of Ganymede or Callisto, much more likely for Europa and especially Io because of their shorter orbital periods. Might be able to see torus emissions at Io, too.

Nightside Jupiter imaging.. auroras, airglows and lightning may well be spectacular. Does the spacecraft go through Jupiter's shadow?.... High phase angle ring images which really brings out faint ring-dust features are also potentially spectacular.
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ljk4-1
post Nov 9 2005, 02:30 PM
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QUOTE (Decepticon @ Nov 8 2005, 06:21 PM)
Will this probe carry a gold disk of some kind? Ala Voyager/Pioneer
*


Go to this post for a response from the New Horizons team on their decision not to include any kind of message/information packet:

http://www.unmannedspaceflight.com/index.p...indpost&p=25901


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"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

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