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KBO encounters
tasp
post Aug 4 2008, 07:07 PM
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Not sure I am thinking this through correctly, but if the number of smaller objects increases fast enough, do we get to the statistical likelihood of a useful non targeted encounter (light curve, size determination, confirm no satellite/binariness) of any objects in the 5 km size?

Maybe a better question is, are there enough 5 km 'rocks' that the possibility of useful science (with no additional fuel used) in a 6 year XM exists ?

Seems like the NH spacecraft 'useful encounter sphere' is rather large, and as it traverses the belt would it intersect anything tiny but interesting?
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Alan Stern
post Aug 4 2008, 07:20 PM
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QUOTE (tasp @ Aug 4 2008, 08:07 PM) *
Not sure I am thinking this through correctly, but if the number of smaller objects increases fast enough, do we get to the statistical likelihood of a useful non targeted encounter (light curve, size determination, confirm no satellite/binariness) of any objects in the 5 km size?

Maybe a better question is, are there enough 5 km 'rocks' that the possibility of useful science (with no additional fuel used) in a 6 year XM exists ?

Seems like the NH spacecraft 'useful encounter sphere' is rather large, and as it traverses the belt would it intersect anything tiny but interesting?



Could be, but no one knows (i) how many objects there are that small-- or how to see them from Earth, so it's impossible to estimate well and even harder to find one and aim for it. NH can't do the job-- the imaging FOVs are too small and the bit rates too low. Believe me, we've thought of all this years ago.

Alan
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tasp
post Aug 4 2008, 07:47 PM
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Thanx.

I guess we get to work out the statistics for the smaller bodies the old fashioned way.

Counting craters on the bigger ones we can see.



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nprev
post Aug 4 2008, 07:49 PM
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Alan, what is the search magnitude limit for the hunt? If you're talking 70km objects or smaller at that distance, I'm gonna guess mag 24 or lower...amazing!!!


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Alan Stern
post Aug 4 2008, 09:13 PM
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QUOTE (nprev @ Aug 4 2008, 07:49 PM) *
Alan, what is the search magnitude limit for the hunt? If you're talking 70km objects or smaller at that distance, I'm gonna guess mag 24 or lower...amazing!!!



28th magnitude.
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nprev
post Aug 4 2008, 09:18 PM
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THAT is a definite "wow!!!!" Absolutely amazing; didn't know that modern CCDs would go that low, even with such enormous light buckets!

Man...I can really understand the need for the field to be clear of Sag now much better. I thought that maybe you guys could still do something now, but it'd have to be a major object to stand out from that mess.


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xtruel
post Aug 5 2008, 04:10 PM
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QUOTE (Greg Hullender @ Aug 3 2008, 06:01 PM) *
Trouble is, it'll take NH almost 10 years to go 40 AU, and the inner edge of the Oort Cloud is estimated to be about 2000 AU out. A 500-year extended mission is probably asking for too much. :-)

http://en.wikipedia.org/wiki/Oort_cloud

Since Sedna's the only thing like Sedna, I think it'll be hard to guess that we'll find another before 2015 AND that it'll be reachable by NH.

That does raise an interesting question, though. From the NH mission page: http://pluto.jhuapl.edu/mission/mission_timeline.php it's not clear how much time NH could have to reach a KBO. A ten-year extended mission could roughly reach the perihelion distance of Sedna from the Sun, but is anyone contemplating an XM that long? How long can we reasonably expect NH to work?

--Greg


My former question may be reformulated as follows : After completion of extended mission at KB, NH’s mission officially ends. Spacecraft will be at something like 50 AU. Maybe some fuel will still be left. From this point, will be something else worth trying ? Previous outbound spacecraft (Pioneers, Voyagers) have all been maintained until they really die, we may expect the same for NH. I had in mind a possibility of targeting some object at scattered belt (however small it might be) which may be a SDO or an object currently cruising near perihelion whose orbit type is similar to Sedna (70-1000 AU or the like), thus qualifying as “inner Oort cloud object” as I’ve read somewhere. But according to Alan’s info I now believe this as unrealistic as SDOs are simply too far apart. So next possible milestone would be escape from heliosphere ?

This is very long term thinking, I agree…
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vjkane
post Aug 5 2008, 04:38 PM
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QUOTE (xtruel @ Aug 5 2008, 05:10 PM) *
So next possible milestone would be escape from heliosphere ?

This is very long term thinking, I agree…

The Voyagers and Pioneers had capable particles and fields instruments. Anyone know if NH's SWAP and PEPSSI instruments would be good for exploration of the heliopause? Also, NH left Earth with a smaller than expected payload of plutonium. How far could it go and still (1) operate the instruments and (2) call home?


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Alan Stern
post Aug 5 2008, 05:39 PM
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QUOTE (vjkane @ Aug 5 2008, 04:38 PM) *
The Voyagers and Pioneers had capable particles and fields instruments. Anyone know if NH's SWAP and PEPSSI instruments would be good for exploration of the heliopause? Also, NH left Earth with a smaller than expected payload of plutonium. How far could it go and still (1) operate the instruments and (2) call home?



We could probably run the s/c and 1 instrument to the mid-2020s to explore the heliosphere 50-70 AU, but that's not the mission-- the mission is to maximize the KB science, and that means spending all the fuel to do that.

Alan
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IM4
post Aug 17 2008, 10:41 AM
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We have no candidates for close KBO enccounters, but what about distant ones? My program predicts that en route to Pluto and beyond NH will pass by several Centaurs within 1-3 AU :

CODE
_____Object_________ Distance(AU)____Date_____
83982  Crantor         2.76325     2010-Mar-08
15810  1994 JR1        0.50739     2016-Jun-03
       1996 KV1        2.61944     2017-Nov-23


That's too far for detailed imaging but I believe useful photometric science (phase curve or something) can be obtained with LORRI or other instruments. Of course that make sense only if LORRI is sensitive enough, since apparent magnitude of these objects will be ~ 16-17m.
Are there any plans for such kind of science?



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Alan Stern
post Aug 17 2008, 11:49 AM
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QUOTE (IM4 @ Aug 17 2008, 10:41 AM) *
We have no candidates for close KBO enccounters, but what about distant ones? My program predicts that en route to Pluto and beyond NH will pass by several Centaurs within 1-3 AU :

CODE
_____Object_________ Distance(AU)____Date_____
83982  Crantor         2.76325     2010-Mar-08
15810  1994 JR1        0.50739     2016-Jun-03
       1996 KV1        2.61944     2017-Nov-23


That's too far for detailed imaging but I believe useful photometric science (phase curve or something) can be obtained with LORRI or other instruments. Of course that make sense only if LORRI is sensitive enough, since apparent magnitude of these objects will be ~ 16-17m.
Are there any plans for such kind of science?



Yes.
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IM4
post Aug 17 2008, 03:18 PM
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QUOTE (Alan Stern @ Aug 17 2008, 11:49 AM) *
Yes.

Interesting.
Any details?
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Explorer1
post Apr 14 2010, 04:42 AM
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Looks like the 'flyby' of Crantor came and went. Did anything significant happened?
Probably not, since no mention on the NH twitter feed, I checked.
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Hungry4info
post Apr 14 2010, 01:56 PM
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Couldn't blame them if they didn't do anything. Not a whole lot you could do at 2.76 AU.


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Vultur
post Apr 15 2010, 09:15 AM
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The first post in this thread says the search would start in 2010 - has it started yet, or will it be later this year?
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