Hi,

I’m regular follower of NH and I’m also interested in the 2nd leg of the mission, i.e the 2016+ KBOs encounters. Does anyone know when operations about this leg (starting with searching objects of interest with HST or some other earth-based means, I suppose) are expected to begin ?

Hiya, X. If I remember correctly, the KBO search isn't really going to kick into gear until 2010 because Pluto (and the cone of possible follow-on destinations) is in Sagittarius from our viewpoint right now, which is the galactic core region...too much background optical 'noise' from all those stars to distinguish targets. Once it moves clear, the hunt will begin. Don't think that HST will participate (might be wrong), but several large ground-based observatories will certainly be involved.

KBO searches will be conducted in 2011-2012, when the relevant KB fields are out of Sag as Nprev described. Target characterization and prioritization will occur in 2013-2014. Target selection will be in 2015.

HST's FOVs are too small to use profitably for searches. We will use wide field imagers on groundbased, big guns like Keck, Subaru, etc.

-Alan

Remember when they called asteroids "the vermin of the sky"?

...our definition of celestial vermin seems to be shifting, doesn't it? Bloody core stars...

Thanks for these quick replies

Given the tiny angular size of expected objects, It seems likely that science data about them to be collected by earth-based means, in order to perform target characterization & selection, will be limited, and may be already known in its headlines. Orbit characterization, absolute magnitude, color may be among these. Are there others ? In particular, will it be possible by earth-based means (or HST) to detect & characterize a binary object and is there a reasonable probability to find one ?


I also wonder if there is some hope that NH after its KBO mission may be aimed at an « inner Oort-Cloud object » (Sedna-like) as these objects raise currently deepest mysteries about how they formed, how they have been put in there, etc... . This would need some fuel left, and also long term NH survey and survival. Clearly this is not currently planned, but this may be the first realistic opportunity to have a close look at Oort cloud...

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

We're hoping for a 4-6 year extended mission (XM), taking us to perhaps 50 AU. The heart of the KBO population is at 42-43 AU, and after that it thins out. By 55 AU we're out of the Classical Belt and into the much more dilute Scattered Belt.

We expect to fly by 1 or perhaps 2 KBOs each ~40 km in diameter in the XM. Larger ones are too few and far between to reach with our fuel supply unless we are very lucky, but the statistics are against us.

My job as PI is not to fly as far as we can but to maximize the value of the KB exploration we can achieve. This translates to accomplishing one post-Pluto KBO flyby within 2 or 3 years if we possibly can (to ensure against later failures) and to pick up a second KBO for comparative purposes if possible thereafter.

-Alan

Is larger necessarily better? Planets (in the hydrostatic sense) are always interesting, of course, but geology has a way of erasing information. A 40km KB equivalent of a chondritic meteorite would be fascinating, if frustrating given only a few hours of remote sensing are possible.

I love the audacity of it, though, to go off to study something without having discovered it yet.

We'll see it for days on the way in, possibly longer. And FYI, 40 km is Eros size.

Alan

Just out of curiosity, Alan, is encounter relative velocity for KBOs basically a constant? These things have very small heliocentric relative speeds if they are not in highly elliptical orbits, so NH's outbound velocity is presumably a criterion for deciding whether or not to select an object based on encounter timing & size (i.e., you'll get a lot more hang-time for a 500km diameter KBO then a 40km).

Nprev-- All KBO encounters are at approx the same relative speed, ~12-15 km/sec, independent of KBO size. Don't know whatyou mean about hang time...

Alan

Oh, sorry. What I meant is that presumably more data (esp. imagery) could be acquired when encountering a larger object then a smaller one; for example, a larger one would have resolvable features further out & also post fly-by.

True, but the stats just make it unlikely--too few and far between. Best we can realistically hope for is 70 km diameter if I choose to go to just one instead of 2 KBOs. That's what the Monte Carlo models for detection statistics within our accessible region after Pluto tell us. Nontheless, the KBOs we will get will be 10^5 times the masses of km-scale comets and will teach us an enormous amount about KBO evolution, chemistry, geology, etc.

-Alan

Thanks for the correction, Alan. And yes, I should have said 'parent body of' somewhere in there.

Here's hoping that you get enough options to do some trading (red? grey? hot? cold? scattered?).

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

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.

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.

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.

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…

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

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 :



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.

Interesting.
Any details?

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.

Couldn't blame them if they didn't do anything. Not a whole lot you could do at 2.76 AU.

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

Actually, Alan said in this post that the search won't start till next year.

Our best imager, LORRI, can resolve the size of an object from roughly 10^5 object diameters away. So for a 100 km object, for example, we have to be w/i 10^7 km just to resolved it; if you want crude shape information, cut that to 10^6 diameters, and if you want "geology," well, better come to approx 30,000 diameters or better. The point here is Crantor and other distant flybys don't yield much of use, so we have not expended effort on them.

As to our KBO search, John Spencer is leading the organizational effort to recruit search teams; Andrew Steffl is helping John. Our plan is to conduct the search in 2011 and 2012, though Scott Shepard at least has already begun.

-Alan

Yeah, I think the last few times we've asked this question (maybe we need an FAQ section for each long-term mission) the answer was "not until we're past the orbit of Uranus."

--Greg

Alan, thanks for the info, but I'm a little confused... I assume that for crude shape information, you mean cut the maximum distance to 10⁶ kilometers, since 10⁶ diameters would be 10⁸ kilometers. But which do you mean for the "geology" figure? 30,000 diameters would be 3 million kilometers for our theoretical 100 km object, which is tough enough, but 30,000 kilometers is more or less a bullseye: better targeting than even Apophis will manage . It seems to me you could get at least some worthwhile surface-feature resolution at a greater distance than that. The famous LORRI images of Tvashtar's plume resolved fine details at 2.5 million km. On the other hand, I know that spacecraft (and ground) resources are limited, and you have to be sure you're getting enough meaningful data for any expenditure. Could you give any hints as to when you think it might be worthwhile to observe during one of these flybys?

The Tvashtar plume images were taken a lot closer to the sun than any KBO images will be. I imagine blurring due to longer exposure times would reduce resolution at comparable distances.

I'll chip in here. Alan was talking about science at Centaurs that we might fly past on our way to Pluto- none of those will get close enough to be resolved. For the KBO target(s) beyond Pluto, we will deliberately target to get within a few tens of thousands of kilometers or closer- from 20,000 km, for instance, we would get 500 pixels across a 50 km KBO- sufficient to do some serious geology. LORRI can get well-exposed, unsmeared, images at Pluto's distance from the sun (it was designed to do that, of course), and while illumination conditions will be more challenging further out in the Kuiper Belt, there's enough performance margin that we expect to be able to do the same there.

At Crantor's distance, a LORRI pixel is 2000 km across, much bigger than Crantor itself. So there's no hope of getting any shape information.

And to make sure no-one is still confused on this point, we will not be searching for KBOs with NH itself- huge ground-based telescopes with wide-field imagers can do that much better, even though they're stuck at 1 AU.

John

Talking of KBOs, here's a heads-up that YOU can probably help us to find Kuiper Belt objects for New Horizons to fly by after Pluto, starting in a month or two. We're working with the Zooniverse folks to set up a "KBO Zoo" where you will be able to help us identify moving objects (i.e. potential KBOs) in the Milky Way star fields that we'll be imaging with the Subaru, Magellan, and Canada-France-Hawaii telescopes this summer. Details once the site is up and running.

John

If we find it, can we name it?! I always thought that "Astro0's Orb" had a nice ring to it!

Sweet!

THAT is a rockin' piece of citizen science outreach, John! Very much looking forward to it!

John,
That's great news, can't wait to participate in the search for targets!

The Search for KBO's to begin.

Look for another release in a few weeks, describing how you can help us sift through all those images.

John

Great, I cannot wait!!!

Any update on this?

It's in beta, still several weeks from launch.

What John said - just found out that some of the people behind Galaxy Zoo have teamed with the NH folks to not only look for potential target KBOs (TNOs, whatever name won't get me in trouble), but enlist citizen scientists in the search And if UMSF isn't full of them, I don't know what is . (OK, Galaxy Zoo itself, but that's a different audience...)

At least one additional Zoo of great interest in UMSF is also in the works.

Just got this in the Zooniverse newsletter. I think it should be safe to post here!

New Beta Test for IceHunters

Last week we tested a new Zooniverse project "Ice Hunters" with
Galaxy Zoo: Supernovae and Galaxy Zoo users. Thanks to the help of
more than 3700 of you, we are now ready to expand our beta test to the
full Zooniverse.

To try out the site as a beta tester, go to:
http://demo.icehunters.org
The tutorial is here:
http://demo.icehunters.org/tutorial

The site will launch to the public in late May or early June, so
please keep this address to yourself for now. IceHunters uses data
around the world to look for Kuiper Belt Objects (KBOs), Variable
Stars, and Asteroids. The ultimate goal is to find the Kuiper Belt
Object (or Objects) that the New Horizons spacecraft will be
redirected to after in flies past Pluto in 2015. The data to find that
object is being taken right now. While we wait for it, we have loaded
in testing data from 2004 and 2005; images filed with unknown KBOs,
variable stars, and asteroids that appear as blobs and streaks in the
residuals of the subtracted images. Your name will be associated with
your every discovery, and catalogues will be published next winter.
Help us find new icy bodies today: http://demo.icehunters.org

Here's an update on how the KBO search is going so far.

This year, after several preliminary searches, we are finally kicking off the full-up search campaign. Our searches are possible only near new moon, and so we have obtained a bunch of telescope time once a month, starting with the late April new moon, and continuing in late May (when, by the luck of the draw of the telescope time allocation committees, we have the most time), late June, and late July. Time is divided between the Magellan telescopes in Chile, the Subaru telescope on Mauna Kea, Hawaii, and the Canada-France-Hawaii telescope also on Mauna Kea.

The first run, in late April and early May, on Magellan, went spectacularly well. We had superb weather and seeing (one night's report described "seeing deteriorating to 0.6 arcsec"- if you're an observer you'll know that's an unusual statement), and the data quality looks excellent. We're now in the process of reducing the data- the key step will be the matching and subtraction of pairs of observations taken hours or days apart, so we can remove the gazillion background Milky Way stars and leave behind the moving objects, which will include our potential KBO targets.

In a few weeks we'll be posting subtracted images on a site being developed by our partners at the Galaxy Zoo, where you'll be able help us to search for the moving objects. The late-May data may be the first posted- the late-April run is lower priority because the KBOs are harder to distinguish from asteroids by their motion in April. In the meantime, there's a beta version of the site already available, using data from an earlier (2004) search- I'll post more on that later today, when the site has had a couple more improvements.

John

Finally we can help you, I am so excited!
Just found a dozen objects in first 5 demo images; software is quite simple/straightforward, perhaps image quality section can be improved with more specific comments.
Thanks for this great opportunity!