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New Horizons: Pre-launch, launch and main cruise, Pluto and the Kuiper belt
cIclops
post Feb 22 2005, 02:02 PM
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QUOTE (Alan Stern @ Feb 22 2005, 01:09 PM)
It's not about doing what is best in terms of systems efficiency, it's about minimizing risk. The saying we use is that "better is the enemy of good enough."  There is also that pesky detail of having limited budgets, so aerospace geeks and PIs love to say, "If it ain't broke, don't fix it." Enough said.

"Better is the enemy of good enough" yes I've heard that one before. Apparently it was the motto hung on the wall of Admiral Sergei Gorshkov, father and architect of the modern Soviet Navy, to remind him of the relative quality of the US and Soviet fleets.

Clearly in a project like NH success is the only real measure and that means the
unfailing execution of the baseline mission. Yet as technology advances there is a pattern of significantly reducing risk either by adding more complexity or by using new approaches. The test test test method is limited by the time and resources available and constrained by the design.

"He who knows that enough is enough will always have enough" - Lao Tsu


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chris
post Feb 22 2005, 03:12 PM
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QUOTE
Ten years is a very long time in the software universe, there may be other better approaches such as neural networks available by 2015. To make the most intelligent use of spacecraft resources during encounter is it possible to significantly enhance the software?


In my experience of writing software, the main things that makes for robustness are good design, good developers, and testing, testing, and more testing. The increasing use of techniques like unit and functional testing in the commercial environments I work in is testament to this. And remember that robustness for a spacecraft is orders of magnitude harder than for anything on Earth. You can't push a reset button if it all goes wrong. (The fact that JPL got Spirit back after the flash filesystem cock-up is one of the things that has impressed me the most about the technology on the MERs).

I'm not an expert in neural networks, but a good friend of mine did his PhD on them, and from what he tells me they would be a very bad choice for spacecraft. They are impossible to debug, and often are not doing what you think they are.

This (http://neil.fraser.name/writing/tank/) is a famous neural network story. It may be apocryphal, but I'm told it gives a flavour of the kind of problems you can end up with.

Chris
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djellison
post Feb 23 2005, 12:10 PM
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QUOTE (Alan Stern @ Feb 19 2005, 04:25 PM)
Attached is a picture of New Horizons in build from last month. Enjoy!

For those trying to get their bearings - we're looking at the side onto which the RTG will be mounted. the SWAP instrument is sticking out on the right by the bunnysuited engineers. ALICE and RALPH are sort of hidden round the corner on the left - and above SWAP on the right just under the HGA is PEPSSI

I hereby award NH with the Acronyms-of-the-Year award smile.gif

Doug
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Borek
post Feb 23 2005, 01:07 PM
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What spacecraft stabilization will be used during cruise phase? Will it be spin-stabilized? If yes, is there any chance of gathering data relevant to the Pioneer Anomaly investigation?

Borek
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djellison
post Feb 23 2005, 01:38 PM
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Well - attitude is all done with thrusters (no reac. wheels) , so I guess it'll be spin stab for much of the cruise - despinning for observations as and when appropriate - Alan will fill us in I'm sure

Doug
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Alan Stern
post Feb 23 2005, 02:20 PM
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Yes, we spin most of cruise, stopping only rarely. It costs fuel that we want to hoard for encounters and KBO DeltaV. And yes, our radio science team hopes to look for
the Pioneer anaomaly. Contact Len Tyler or Ivan Linscott at Stanford.

-Alan
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cIclops
post Feb 25 2005, 07:10 PM
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For those interested in how such things are done now here is a link to an index of the draft environmental impact statement for NH.


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Alan Stern
post Feb 27 2005, 05:18 PM
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For those interested, various interesting information aboiut New Horizons can be found at www.boulder.swri.edu/pkb

And here is another nice image some may wish to download.
Attached thumbnail(s)
Attached Image
 
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MiniTES
post Feb 27 2005, 09:18 PM
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Dr. Stern, what, if any, flyby science are you planning to do at Jupiter, assuming that there is a Jupiter flyby?


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"Too low they build, who build beneath the stars." - Edward Young
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Alan Stern
post Feb 28 2005, 01:02 AM
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Extensive Jupiter system science is planned-- a great deal focus on meteoroligical
inviestigations of Jupiter using IR imaging spectroscopy. There is also a good bit of
satellite imaging and spectroscopy, stellar occulations of Jupiter's atmosphere, dust studies in the Jovian system, and a magnetospheric tail explortation that is wholly unique becaue NH will fly down the tail hundreds of AU as it exists toward Pluto-Charon.
One dirty little secret of NH: We'll return far more bits from Jupiter than Pluto,
largely becasue we can, given the closer range.

We also plan to use Jupiter as a cal target and as ops practice on the way to Pluto.
(and we just found a Centaur to study-- albeit from long range, in 2010-- 2002 GO).

-Alan Stern
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tedstryk
post Feb 28 2005, 01:37 AM
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I have read that closest approach won't be too far outside the orbit of Callisto. Will Callisto actually be nearby. Also, with its telescopic capability, what kind of resolution will New Horizons be able to get on the Galileans?


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MiniTES
post Feb 28 2005, 01:43 AM
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QUOTE (tedstryk @ Feb 28 2005, 01:37 AM)
I have read that closest approach won't be too far outside the orbit of Callisto. Will Callisto actually be nearby. Also, with its telescopic capability, what kind of resolution will New Horizons be able to get on the Galileans?

To add to that, how will that compare with Galileo and Voyager images? Have the parts of Callisto or the other Galileans that could be imaged at a high resolution already been imaged at such a resolution by Galileo or will they be new areas?


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Alan Stern
post Feb 28 2005, 03:12 AM
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All this depends on which day in Jan 2006 we launch, which in turn ocrresponds to which day in 2007 we arrive at Jupiter. Callisto and other moons way be close, or may be far--- depending on when we arrive. What we can say for sure-- now in 2005-- is this:
the cloest approach of NH to Jupiter will be almost 4 times closer than Cassini, i.e., at about 38 Rj.

-Alan Stern
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tedstryk
post Feb 28 2005, 03:25 AM
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Assuming there are no delays from Jan 2006, what kind of resolution could LORRI get for Io? (I figure it won't vary nearly as much as Callisto no matter where it is, unless it is behind Jupiter at closest approach)

Thanks,

Ted


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Guest_BruceMoomaw_*
post Feb 28 2005, 06:25 AM
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I attended the 2003 DPS meeting -- and, specifically, the special session on science goals for NH's Jupiter flyby. The impression I got is that the most interesting aspect of that flyby will be, not its imaging of the moons, but its near-IR spectra of them -- which will be much better than those from either Galileo or Cassini (better instrument than the former; much closer than the latter), and may well provide us with very interesting new data on their surface compositions.
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