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Unmanned Spaceflight.com _ New Horizons _ Pluto Predictions

Posted by: Juramike Oct 3 2008, 04:50 PM

Dunes.

And basins.

Maybe not as thoroughly chemically processed as Titan's basins, but basins.



What do you think New Horizons will find at Pluto? How will Pluto surprise us?

-Mike

Posted by: ElkGroveDan Oct 3 2008, 04:52 PM

One or more very small previously undetected satellites.

Posted by: SFJCody Oct 3 2008, 05:54 PM

I like http://www.unmannedspaceflight.com/index.php?s=&showtopic=265&view=findpost&p=1233
I think we're going to see a really diverse mixture of surface ages underlying the seasonal frosts. There will be four main surface types: (1) really old cratered regions (both bright and dark) that resemble Iapetus, (2) faulted regions (like parts of Enceladus, Ganymede etc) and (3) Triton-like 'cantaloupe terrain'.

What about type 4?

I think there will be a major difference between the terrain on the hemispheres of Pluto & Charon facing each other and the hemispheres facing away. As Earth-Moon is perhaps our best analogue for this kind of situation I will say that these facing hemispheres will have cryovolcanic maria.

Posted by: remcook Oct 3 2008, 06:51 PM

My image is always a frozen-out Titan smile.gif

Posted by: Pavel Oct 3 2008, 07:35 PM

A planet wink.gif

Well, I guess we'll see something like Europa, but heavily cratered and much dirtier.

Posted by: 3488 Oct 3 2008, 09:30 PM

I think Pluto will be ancient & cratered with little else.

Triton was most likely a captured Dwarf Planet by Neptune. During capture the orbit was very elliptical, thus raising huge tides that heated up the interior (much like Jupiter with Io), initiating massive cryovolcanism that resurfaced Triton. When the orbit settled down, tidal flexing reduced & a new surface froze.

Pluto, as far as is inferred, has never undergone such heating. I think a Triton, Europa, Enceladus, Dione, Ganymede, etc type surface is just wishful thinking. Sure there are ices present & these ices may migrate dependent on the season & the point of the elliptical solar orbit, but Pluto & for that matter the larger & more massive Eris do not appear to have been subjected to violent heating that Triton had.

I think Pluto will look more like Callisto, Rhea or Iapetus. Mostly craters, with perhaps a few fractures. I may be wrong, but that's exploration.

Andrew Brown.

Posted by: ilbasso Oct 4 2008, 03:55 PM

I'm not so sure that Pluto is inactive. Observations by the Gemini Observatory in 2007 suggest that Charon may have cryo-volcanos. Since the two objects are tidally locked and relatively close in mass, I wonder to what extent they keep each other geologically active. It certainly will be interesting to see what plays out!

Posted by: Hungry4info Oct 4 2008, 05:15 PM

My guesses,

Pluto may be found to have been active in the past.
I expect Pluto to be more heavily cratered than Charon.
Nix and hydra, will probably resemble Phobos and Deimos--dead, cratered rocks.
I'm thinking there might be a sort of Hellas basin on Pluto. An impact would nicely produce a bunch of little moons.
I'm expecting Charon to be slightly active, and Pluto effectively dead.

Posted by: dvandorn Oct 4 2008, 05:32 PM

I'm expecting to see strong tectonic effects on both Pluto and Charon. I think tidal effects will have caused a lot of surface disruption on both bodies.

I also think it's possible that Charon, at least, may resemble Umbriel as a body that has been roughly re-assembled from the crushed remnants of an earlier body. The total angular momentum of the Pluto-Charon system resembles that of the early Earth-Moon system, which supports the idea that Pluto and Charon have a similar big whack kind of history. Pluto may show some very interesting signs of a post-impact redifferentiation, but Charon may be just below the size limit to have re-differentiated. It all depends on how long ago their big whack occurred, and the materials involved, of course, and while we have some hard compositional data, it's not exact enough to plug into a pretty formula and get Pluto/Charon out the other end.

So, I expect to see what we're going out there to see -- something unlike anything we've ever seen before.

smile.gif

-the other Doug

Posted by: Juramike Oct 5 2008, 12:00 AM

I think that Mars is to Earth as Pluto is to Titan.

I imagine Pluto as an older and colder version of Titan.

I wonder if at some point in the far deep past that Pluto had a substantial nitrogen atmosphere and might've gotten warm enough to support a nitrogen ocean. Maybe there is a possible scenario where Pluto had a full meteorological cycle involving nitrogen (azatological cycle?). Nitrogen rains condensing out onto a frozen hydrocarbon surface, carving out channels, filling in basins, and making dunes from hydrocarbon sediment blown in a nitrogen wind. Then over time the nitrogen was lost, or froze out, and everything dried up.

The tidal effects of Charon may give Pluto two different faces. A warmer one towards Charon due to tidal effects, and a colder one facing away from Charon. The cooler one probably looking older and more crater-ridden (and maybe covered in nitrogen frost that moved from warmer hemisphere to the colder one.)

While Pluto will be surprising, I'll bet Charon will be fun.

-Mike

Posted by: volcanopele Oct 5 2008, 01:33 AM

Okay, I'll bite.

Charon will look a lot like Dione. Mostly cold and dead with a few large impact basins. Extensive tectonic fractures will be visible on the sub-Plutonian hemisphere, but billions of years have passed since those fractures were last active.

Pluto will look quite similar, but the effects of a thin atmosphere will increase the rate of erosion, smoothing out a number of older impact basins. New Horizons will spot a number of flow-like features, leading to a huge debate over whether those features were carved by ancient cryovolcanism or from nitrogen/methane flows from a time when the atmosphere may have been thicker.

Posted by: Hungry4info Oct 5 2008, 02:25 AM

QUOTE (dvandorn @ Oct 4 2008, 12:32 PM) *
I also think it's possible that Charon, at least, may resemble Umbriel as a body that has been roughly re-assembled from the crushed remnants of an earlier body.


Do you mean Miranda?

Posted by: dvandorn Oct 5 2008, 02:43 AM

Um, yeah.... Miranda, that's the ticket...

rolleyes.gif

the other Doug

Posted by: nprev Oct 5 2008, 07:45 AM

Hmm. Interesting thoughts here from VP, oDoug & Hungry that I'll shamelessly derive from:

Pluto will look like one of the midsized Saturnian moons...sort of like Tethys, actually, with more weathering from the presence of a periodic atmosphere, low topography from an episode of global crustal melting, and perhaps even a slight resemblance to Vesta with a big honkin' oblique crater as an artifact of the event that produced Charon, Nix, Hydra & any as yet undiscovered moons.

Sorry, but can't buy off on the Miranda possibility...too many orbits (and too much distance traveled; thinking fragment trajectory divergence over time) needed to put Humpty-Dumpty back together again, if that is indeed the correct explanation for Miranda's appearance.

Posted by: Decepticon Oct 5 2008, 02:15 PM

For what it's worth...

I expect Pluto to be Triton like mixed with a dash of Ganymede.

And Charon similar to Ariel.





PS I expect something totally unexpected as usually. The 2 newer moons I believe with be very interesting.

Posted by: Rob Pinnegar Oct 6 2008, 01:44 AM

QUOTE (Decepticon @ Oct 5 2008, 07:15 AM) *
PS I expect something totally unexpected as usually. The 2 newer moons I believe with be very interesting.


I'll be really interested to see the details of how Nix and Hydra's orbits work. They should deviate pretty noticeably from ellipses because of the mutual motion of Pluto and Charon.

I understand that some work has already done in this direction (i.e. predicting the orbital paths); it'll be neat to see whether the predictions are accurate. One would think they would be, but we could always get a surprise.

As for Pluto and Charon -- really, we can forget about predicting anything for our first close-up look at a KBO, apart from Triton which is really in a class by itself. If we're spectacularly lucky, we might be able to see some lingering evidence of the impact that created Charon (apart from Nix and Hydra's existence). I think that would be asking a bit much, but you never know.

Posted by: Vultur Oct 6 2008, 08:56 PM

I don't know, but I'm sure it will be informative even if it's "just" an ice ball.

Posted by: mchan Oct 7 2008, 06:02 AM

QUOTE (dvandorn @ Oct 4 2008, 07:43 PM) *
Um, yeah.... Miranda, that's the ticket...

IIRC, Miranda features like the chevron are from upwelling rather than result of re-assembly of remnants of body disrupted by collision.

Posted by: Fran Ontanaya Oct 7 2008, 06:55 AM

Cryovolcanos and a gravity center outside both bodies could produce something interesting. Is it physically possible that moonlets like Nix and Hydra formed by aggregation at the gravity center and then migrated to their current orbits?

Posted by: Rob Pinnegar Oct 9 2008, 01:08 AM

QUOTE (Fran Ontanaya @ Oct 6 2008, 11:55 PM) *
Cryovolcanos and a gravity center outside both bodies could produce something interesting. Is it physically possible that moonlets like Nix and Hydra formed by aggregation at the gravity center and then migrated to their current orbits?

No, they couldn't have done that -- the gravity centre (also called the barycentre in technical terms) wouldn't be a good place for aggregation. It's close to Pluto and so anything that tried to clump together there would have ended up falling onto Pluto pretty quickly. Even if something *could* have built up there, it couldn't have migrated outward, as it would have crashed into Charon on the way out.

Aggregation at the Lagrange points probably wouldn't work either. I don't have the math handy but as I recall, Charon is too massive for that to happen.

One current theory for the formation of the Pluto-Charon system, which seems to be in vogue right now, it that it was created by a giant impact early in Pluto's history. Basically, a large object hit Pluto, and some of the "splash" went into orbit and accreted into Charon. Some of the left-overs from this process ended up as Nix and Hydra.

A similar process is thought to have created the Earth-Moon system as well -- though this has been a point of controversy for a very long time in planetary astronomy.

Posted by: Juramike Oct 9 2008, 04:21 PM

After such an impact, there must've been an aweful lot of tidal friction generated on both bodies as the system locked up into its current configuration. How much heat would have been generated, and how would this have affected the crust and surface of Pluto?

Even now, how much tidal libration is in the system? (How eccentric is Pluto-Charons orbital couple?) And would this tidal energy get evenly distributed or would there be sub-crustal hotspots at certain points?

-Mike

Posted by: Rob Pinnegar Oct 11 2008, 02:25 AM

QUOTE (Juramike @ Oct 9 2008, 10:21 AM) *
After such an impact, there must've been an aweful lot of tidal friction generated on both bodies as the system locked up into its current configuration. How much heat would have been generated, and how would this have affected the crust and surface of Pluto?

Even now, how much tidal libration is in the system? (How eccentric is Pluto-Charons orbital couple?) And would this tidal energy get evenly distributed or would there be sub-crustal hotspots at certain points?

-Mike


Well, ultimately the energy would have had to come from the orbital energy of Pluto and Charon around each other. That would put limits on the available energy. This wouldn't be an Io-like case where the energy source is Jupiter's rotation, which for all intents and purposes is inexhaustible.

Maybe a little energy could come from librational motion, but it's hard to imagine it could amount to much.

One other thing to keep in mind is that Pluto and Charon are mutually tidally locked. That means that Charon shouldn't be moving away from Pluto any more, the way the Moon is gradually moving away from the Earth. Their orbits around each other are fixed, except for solar perturbations, and what little comes from Nix and Hydra and other KBOs, and the giant planets.

Actually, I guess that some information about the past evolution of this system might be obtained by observing that Nix and Hydra don't appear to have been captured into resonances with Charon (at least this was the case last time I read up on it). That implies that there couldn't have been *too* much tidal energy dissipated. If there had been, Charon's semimajor axis would have increased enough for Nix and Hydra to get "grabbed" into resonances at some point.

(Mind you, Charon's so big relative to Pluto that it would take a *lot* of slowing-down of Pluto's rotational period to move it out very far... hmmm, this gets more complicated. Guess I might have to stop speculating, and actually do the math.)

Posted by: Rob Pinnegar Oct 15 2008, 04:46 AM

After thinking about this a bit more:

If the giant-impact model of Charon's formation is correct, it's likely that Charon formed quite a lot closer to Pluto than is the case today. This means that it may originally have had an "egg-shaped" profile (similar to Mimas) caused by tidal effects.

Eventually, Charon moved outwards, and the system reached the mutually-tidally-locked configuration. However, with Pluto's mass being so small, I wonder if Charon's orbital evolution could have proceeded slowly enough for the moon to solidify completely before it reached its current distance from Pluto?

If that's the case, Charon may show some features characteristic of relaxation of an initially ellipsoidal solid body to a more circular shape. Sort of a reverse version of what happened to Iapetus, maybe?

Posted by: peter59 May 16 2010, 07:06 PM

2010 Hydra-Nix Meeting Webcasts May 11-12, 2010
https://webcast.stsci.edu/webcast/searchresults.xhtml;jsessionid=FEEF69927476DCB92A6E2AD7BA6A2EE0?searchtype=20&eventid=129&sortmode=1
Unfortunately, English is not my native language. I have a problem with understanding the spoken english language. Maybe you can find here some interesting information about Nix and Hydra.

Posted by: brellis May 16 2010, 09:34 PM

Didn't Hubble see an atmosphere when Pluto was closer to the sun? If so, might NH see evidence of that atmosphere refreezing and recently falling back to the surface?

Posted by: Juramike May 16 2010, 10:04 PM

Recent observations indicated that there might be a lag in the freeze out of Pluto's atmosphere. It might be just starting to freeze out as NH buzzes past.

From Pasachoff et al. The Astronomical Journal 129 (2005) 1718-1723. "The structure of Pluto's atmosphere from the 2002 August 21 stellar occultation."
Freely available http://74.125.155.132/scholar?q=cache:EKui1sTcqwUJ:scholar.google.com/+Pluto+atmosphere+pressure+altitude+plot&hl=en&as_sdt=40000000000. (as html, click for pdf version)

"The current increase in temperature and pressure seems to prolong the period in which the atmosphere will remain detectable before its collapse, making it more likely that New Horizons will be in time for atmospheric studies at Pluto. The current data are consistent with the model of Hansen & Paige (1996, Fig. 11) that shows a cooling beginning in 2015, not far from the spacecraft’s prospective arrival."

Posted by: Greg Hullender May 17 2010, 01:38 PM

I hope that doesn't mean we're likely to be there on a cloudy day!

--Greg

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