My first impression was that the bright heart (made of frozen CO and not CO2...) looked like a "banquise" or an ice pack.

The black patches along some limits of the polygons seem to be in line with my initial assumption according to which there is a layer of liquid hydrocarbons (methane, ethane...) beneath this bright uniform crust.

At what depth?...

Possibly the largest reservoir of liquid hydrocarbons is hiding beneath this intriguing area! Who knows?

That's my bet!

Lots of good suggestions for what is happening at Tombaugh. Gladstoner you have marked ground zero for the beginning of Charon's grazing impact. In the You Tube video stop it at 34 seconds. The depression and shock wave effects have piled up the mountains to the side of a deep circular depression, its rim wall peppered with sublimation features that look like golf bunkers. The mountain that looks like a Cathedral in this view is gigantic. We have seen before how moving images make perspective and detail easier to see and I suspect Alan has seen that and added it to improve the image presentation.

https://www.youtube.com/watch?v=ydU-YrG_INk

So some thoughts following a lengthy perusal of this avalanche of information.

This shot is of the very tip of the Ice Cream cone part of Tombaugh. That ice cream cone is made up of frozen Carbon Monoxide. Imagine some giant bucket of fluid Carbon Monoxide was poured on top of the existing surface of Pluto, which is a frozen Nitrogen/Methane ice layer on top of a Water Ice layer beneath. Eventually, all fluid flow stops and it freezes. The deepest point of Charon's impact is marked by the crown of the Carbon Monoxide contour map. Towards the top of the Sputnik Plain image, there is a large slightly brighter, circular area which appears to be higher and hence colder than the more Southern areas of the Carbon Monoxide Ice sea/cap, which reflects that map nicely. It is noticeable the cracks are shallower and devoid of the hills/mounds and with very few areas of dark material. At its crown is a lonely dark spot. Sublimation pit, sinkhole, geyser? No Idea.

Beneath this area's now highly impact and shock compressed surface, it may have triggered a phase change in the "bedrock" Water ice below. This releases heat and starts to warm the N2/CH4 ice mixture from below, adding to the heat from the initial impact, superheated atmosphere and shock wave, from above. Whether its enough to liquify the mixture is an open question, but convection and sublimation will occur within such "warm", porous ices. If considerable amounts of gas are trapped below the CO ice sheet the expansion of gas could create enough pressure to create the polygonal pattern.

Where cracks appear in the ice, probably forced open by the pressure from below, the Methane and Nitrogen gas are released at the surface where they are exposed to a very low pressure, gaseous Carbon Monoxide, together with UV and Cosmic Radiation. Throw in a bit of micron sized interplanetary dust, result, lots of organics, hydrocarbons, Tholins, and PAHs, which are cooked to a dark brown sludge. It may only be millimetres or centimetres thick, but the albedo contrast is stark making its distinction from shadow, difficult.

The escaping Methane and Nitrogen gas will soon freeze as an upside down icicle. Of course from long cracks, or confluences of cracks, hills, ridges and mounds would form, like growing crystals in a saturated fluid. The fact their height seems to be limited indicates they are probably not made of Water ice. Where the ice sheet is thinner, at the margins and towards the South, it is easier for the cracks to form and expand. We see many places where bits of the original underlying terrain show through, either completely or as surface topology. The nature of the original terrain can be seen in the "Ropey Mountains" far to the South, where wind, sublimation, frost deposition and thermal stress have created swirling patterns of valleys and ridges, on top of larger structures of swirling mountain chains separated by immense crevasses and canyons. Sublimation landscapes appear to show this repeating pattern on multiple scales, from micron to kilometres, as seen here and at 67P.

Lets consider Charon, possibly formed as a moon of Uranus, where, in this part of the Solar System, the predominant ices are Water and Carbon Monoxide. The young Charon, possibly undergoing tidal heating from Uranus, may have had a liquid, Carbon Monoxide/Water mixture, ocean below an outer rock hard, sintered, Water ice crust. That freezing out of the Water from the mixture to form the crust, may have concentrated the Carbon Monoxide to the point of separating the two. On its way towards Pluto that crust would have got, colder harder and even more brittle not to mentioned cracked and weakened.

Charon hits Pluto in a glancing blow, brittle ice crust cracks and shatters into huge Water ice chunks, some of which end up strewn across the surface of Pluto as mountains, some escape into orbit. The liquid ocean pours out of the broken shell in a giant flood filling the impact basin with liquid Carbon Monoxide, and liquid Water formed during the heat and pressure of the impact. At the deepest point, the subsequent freezing ice expands to create the central mound. When we see the "toes" at the Northern rim of the ice cream cone, I am expecting to see fjords and canyons carved in the bedrock Water Ice pushed up and ahead of the impact, a landscape similar to that Glacier picture earlier, as Carbon Monoxide/Water ice glaciers, lubricated by Nitrogen and Methane from beneath, carve the landscape.

Evidence for prevailing winds creating the opportunity for aeolian deposition in the lea of cliffs, ridges, hills, mountains and canyons, strongly suspected this and its nice to see some evidence. The comparison to the size of Earth's atmosphere is amazing, Pluto's is bigger than Earth's atmosphere now, it was surely way larger in the past given the modelled loss rate of 500 tonnes a second. The image I most want to see is the one that fits in the corner of the L. That will have that humungous mountain in it.

Finally would it be fair to compare these images and their resolution to an old B&W cathode ray television and the later highest resolution images to a Full HD 1080P TV. It seems about right, in which case this is going to get even more astounding. What a place!

Sherbert, I don't think your fanciful explanation (a grazing impact of Charon created the landscape) takes into the account the TITANIC amounts of energy involved in two planetary bodies of this scale meeting at a speed that exceeds Pluto's escape velocity.

If Charon had a grazing impact with Pluto, a significant part (or almost all) of Pluto's surface would be completely altered by the energy involved, and the ejecta that would rain down on both bodies for an extended time. This would not just leave a nice flat plain and valley. It would not leave a visible scar that would allow you to trace the impact. Not even close.

You are right it is fanciful, its speculation to stimulate discussion and ideas.

Agreed.

Such speculation is fun, but there's something to be said for patience in terms of waiting for all the observations to be received as well. We've seen just a tiny amount of the anticipated data thus far, and it's possible--even likely--that more unexpected features are yet to come which will allow formation of much better hypotheses.

Most definitely!

Besides, if Charon were to "hit" Pluto at a glancing blow, and wind up intact in a capture orbit, that orbit is already unstable by definition. I would expect Charon and Pluto to merge shortly afterward.

So would I.

but since there's not enough data yet there's still room to get fanciful.. so along those lines, if a smaller ex-moon(s) of indeterminate size and composition were to deorbit as it deformed into a diffuse rubble pile that would tend to reduce its monolithic 'impact' legacy as it eventually and more gently joined with Pluto in the post-cratering epoch, depending upon how much of the surface is composed of volatiles that could be liquified by whatever magnitude of energy that may entail, there may be any of all sorts of possible crustal rearrangement resulting in chaotic jumbling of upturned 'mantle' blocks and plains, and all within the 'recent' past, though should such a scenario leave obvious traces on the orbits of the other moons to be ruled out?

I would like to see some higher resolution images from Charon's North Pole, before I speculate further.

Here are the top ten known KBOs with their diameters, with their major moons:

Pluto (2370 km) : Charon (1208 km)
Eris (2326 km) : Dysnomia (685 km)
Makemake (1430 km)
2007 OR10 (1280 km)
Haumea (1920 x 1540 x 990 km) : Hi'iaka (310 km), Namaka (170 km)
Quaoar (1110 km)
2002 MS4 (934 km)
Orcus (917 km) : Vanth (378 km)
Salicia (854 km) : Actaea (286 km)
2002 AW197 (768 km)

Half of the ten KBOs are known to have large satellites! The trend continues among smaller KBOs (allowing for the observational difficulties). Given how common large satellites are around KBOs, I have to think that they formed almost automatically as part of the main KBO formation, as mini-planetary systems. Pluto/Charon would be no exception, in my opinion.

Maybe their isolation in the outer reaches of the Solar System means that their formation was mostly left undisturbed, unlike the chaotic and energetic inner Solar System. So any growing satellites were left in orbit around their primary, without being perturbed away from, or into, them.

I feel like a kid at Christmas time eagerly awaiting the unwrapping of the presents.

Water ice "bedrock: has a density of 0.92, Nitrogen about 1.02 and frozen methane about 0.52. At Pluto's calculated maximum internal pressure, we can say with some confident that water ice would exist as orthorhombic Ice (XI) or possibly some hexagonal ice. There are no major consequences of phase transitions (under normal conditions).

It's not difficult to understand that frozen methane, which behaves like a glass at Plutonian temperatures, would tend to upwell if it ends up below the surface due to impacts, subduction etc.

It's question of how far out of the box you can reasonably think. As Nprev says, there is a vast amount of data yet to come which could change the way we look at Pluto very quickly. So much is tentative.

OK, so how's this for "reasonably far out of the box" ?

1) The Pluto/Charon system orbit is obviously very different from the "regular" planets.

2) The totally unexpected surface morphology of Pluto - almost devoid of craters - is likewise very different from solid bodies (moons) in the outer Solar System.

In other words, Pluto/Charon don't fit.

Ergo, like other "Sednitos", they may be alien worlds captured by the Sun from a passing star:

Leaving aside how it got there, the Carbon Monoxide ice cap is there on top of Nitrogen, Methane, possibly Neon, sitting on a "bedrock" of Water ice. The Ralph Methane map showed high levels of Methane above the North Pole and the Tombaugh Region and not really anywhere else. From the ideas and figures in other posts the burning question, "is there liquid under the ice cap?"

I'm guessing temperatures in Pluto's Northern Hemisphere on July 14th could be equated to mid July here on Earth. Pluto is about a quarter of the way through it's Northern Summer. So for the Pluto we see in these images, at the moment the temperature is approaching the top of the temperature range near the surface, a time when activity in the atmosphere and on the surface is going to be near its peak. How much of the Methane Ralph shows is on the ground and how much in the lower troposphere? That might have a bearing on localised greenhouse heating. With so many volatile mixtures with triple points around these temperatures, local temperature conditions, microclimates, are going to affect the composition of the surface ices and their physical properties. The team say with more detail they will be able to address these questions. That's going to be a real eyeopener as to whats going on.

With Pluto's axial tilt the highest temperatures are towards the Poles. The Tombaugh region seems to be the quickest route for warmer saturated atmosphere to the North to get to the cold South, but its sort of like a funnel, which would speed up the wind even more. Cold air would try to replace it from the South and meet somewhere in the middle where Charon's gravitational influence is also not to be ignored. Jupiter's Red spot comes to mind. Those polygonal structures are just like windblown ice formations on Earth, however on Pluto, that "hurricane" could last for half a Pluto orbit, over a hundred years. Thats going to leave a significant landmark on the surface.

While Pluto's orbit is unlike that of the "regular" planets, it is very typical of the "plutinos", which are, like Pluto, in a 3:2 resonance with Neptune. There are a great many such objects, of which Pluto is merely the largest.

They were originally in closer orbits to the Sun, but would have been swept up by Neptune as it moved outward and trapped in the 3:2 resonance.

Sedna's unusual orbit makes an extrasolar origin possible, but Pluto's orbit looks quite typical of the numerous objects that formed in the inner Kuiper Belt.

Hi everyone- I'm new to this enterprise of Plutonian speculation; could someone direct me to a source that has decent information about its potential to have a magnetosphere?

I'm trying to make sense of that heart shape, as it extends, saddle-like, around the southern pole. Alternatively, could there a possible gravitational influence involving Charon, as I think the "heart" is bisected opposite of the tidally-locked, Charon-facing prime meridian? Could it be a reverse marker of the heart's proportion of sun-facing time, given its quite complex solar orbital attitude?

Or...are these just adorable newbie intuitions and/or possiible misconceptions that have already been addressed in this forum?

Thanks,

Mike

Kewl! Good to have a thread where we can speculate wildly. (ADMIN: With some restraint please. )

I'm wondering why the CO ice is all in Tombaugh Regio on the lit side of the planet. What would cause CO ice to gather just there? Altitude? Temperature? Is there a liquid CO "aquifer" underneath that only wells up here?

Remember that the area is getting the most insolation it will get during the northern summer. Yes, it gets more direct sunlight when the sun is high over the equator, but only for half a Plutonian day, so overall right now, even at a lower angle of incidence, it's getting insolation continuously. So it's not exactly a cold sink.

I think you have to start getting your head wrapped around the 248-year cycle of seasons on Pluto. It spends more than 50 years in each season, and more than a century of continuous insolation on each pole. Cold sinks are going to appear in odd places, build up ices, and sublimate back off as this cycle continues. And I'm thinking that each set of seasons are unique -- topography changes, ice deposition occurs in different places due to vagaries of wind and even weather -- so major ice depositions might occur in different places in different years.

Maybe the CO ice is a remnant of a major deposition that occurred in the best cold sink available on what was then the dark side when a big exposure of CO ice sublimated relatively quickly from the southern hemisphere? And the other ices deposited at the time have preferentially sublimated since the northern hemisphere began its summer, leaving only the harder-to-sublimate CO ice? If so, what around here sublimates more easily than CO ice? And maybe the pitted surface at the southern edge of Sputnik Planum is an example of where those other ices puffed out, leaving holes in the CO ice?

Also -- hitting the various things that have been crossing my mind -- if Pluto is losing 5 tons of nitrogen an hour to space, over four billion years that amounts to nearly 163 and half trillion tons of nitrogen, if that's been a relatively consistent loss rate. How many tons of Pluto is left? How much of the original body has been blown away? And how much more of other lighter elements might have been lost earlier in Pluto's history?

And, to answer my own question, a quick search shows me that Pluto has an estimated mass of 13 quintillion tons. A quick calculation tells me that the amount of nitrogen lost (again assuming a consistent loss rate) is 1.25e-5 percent of Pluto's current mass. So, I guess maybe not so much... sounds like a heck of a lot, though!

-the other Doug

MOD NOTE: Post moved from NH near encounter thread.




This rationale does make sense. Either:

1. All the moons were captured satellites later on;

or,

2. they more or less started like this and captured the Nix's of this world.

I am beginning to think #2.

Triton probably is an exception. But then Neptune is of another size altogether.

And, as usual, when playing with numbers, I got one wrong. Somehow I thought I had just read Pluto loses 5 tons of nitrogen an hour. I find I left off a couple of zeroes, it's 500 tons an hour.

So, I believe that makes the amount of nitrogen lost closer to 16.33 quadrillion tons over four billion years, and that's more like (if I'm figuring the scientific notation right, that was always hard for me to think in) 1.25e-3 percent of Pluto's present mass. More, but still a pretty small percentage. Nothing like the half of a percent that was estimated as little as ten years ago by those who anticipated a lot of gas loss from our favorite little KBO.

-the other Doug

Some years ago, part of the concern for mounting a near-term mission for Pluto was to intercept it before the atmosphere would freeze due to growing distance from the Sun, allegedly shutting down most cycles for the aphelion phase. I have not heard that concern mentioned for awhile, and had quietly reasoned that the concern was resolved with the timely launch of New Horizons. Yet I wonder whether the approaching aphelion season might indeed slow down the energy available for causing nitrogen loss. Thoughts on seasonal influence on gas loss (and how that affects projections about the planet's mass loss)?

A bit hard to read and understand all points here. A simple question and sorry if it has been addressed. Is the Heart facing the opposite direction of Charon? If yes, can it helps explaining all CO is concentrated there? Thanks

At this very early stage in the data release I can't help but speculate about the lineations outlining the 'polygonal' terrain in yesterdays release (17 July). After Habukaz showed us the 'troughs' look like they have ridge-like structure, I was immediately reminded of Enceladus' Tiger Stripes in appearance. But, if the polygonal terrain is due in part to convective cells, then the edges with the troughs should be subducting, rather than venting.

If the edges of the polygons are subdudcting, could the darker, lumpy, blocky material that is associated with the troughs in many places be some kind of bouyant flotsam that has been transported and gathered in these ridges? It seems very strange that the polygon edges have what appears to be so much blocky material in them but not in the polygons proper. The Hi-rez imagery of this and so much more should clarify just what exactly is happenning in these areas.

Couldn't the simplest explanation for CO ice be that it's the area with the highest albedo? The difference between continuous airless insolation on a white surface and a black surface could be big.

Good idea that, maybe the subsurface "aquifer" of CO was penetrated by an impact and the pressure release, belched out a fluid slush of mainly CO. The breach would be sealed over with a "scab" of frozen CO. The raised, brighter, heart of the Tombaugh region comes to mind. An object about the size of the one that knocked out the dinosaurs, might do the trick.

EDIT:- Strangely enough that was about a once in a hundred million year event, the rough boundary mentioned for the timeframe of the most recent activity on Pluto.

Looking at DLD's second, enhanced colour image, the distribution of material across the top of the icecap "land bridge" suggests a west to east flow to the equatorial winds here. It looks like material has been blown out of the dark Whale region up onto the icecap. It appears to be quite sharply bounded on the Northern edge, only small amounts of material have reached the areas of the pits and even less reaching further North to the Sputnik Plain. Prevented by the prevailing North to South atmospheric flow, presumably. There is not enough detail in the Colour map to try and spot turbulence at the boundaries of these gas flow patterns, reflected in the surface colouring. Might be something to look out for in the Hi Res images.

The coloured area, the cone of the ice cream, appears to be considerably lower than Sputnik Plain. The slope between them is seen mainly as the pitted terrain. The pits, almost certainly sublimation features, seem to form on slopes, in roughly parallel rows, created by the different insolation of the slope as shadows move up and down the slope. Similar rows of pits can be seen at the tip of Tombaugh, referred to by JB I think as "nests". I think they look like golf bunkers, except they are considerably larger.

IIRC during yesterday's press conference it was estimated the Nitrogen loss from Pluto would amount to a layer of 1000 - 9000 ft over the age of the solar system.

In the Kuiper belt satellites are common for the largest objects and for objects with low inclinations and eccentricities (called cold classical KBO's) From what I've read the largest objects have satellites because their gravity wells were large enough to retain material from collisions which formed satellites. Many of the satellites around the cold classicals are loosely bound which has is one piece of evidence that these objects formed at these locations rather than being scattered outward by Neptune. In simulations of collapsing clouds of solid particles two objects often form which may indicate that the cold classicals formed as binaries. As far as I know these simulations haven't yet been done for objects as large as Pluto.

So what is different about the Tombaugh Region that Carbon Monoxide ice collects only there in large amounts. This image shows the approximately real orientations of Charon and Pluto, and how the icecap relates to Charon.

http://www.nasa.gov/sites/default/files/th...d-charon-01.jpg

The tidal bulge in Pluto's atmosphere is on top of the Tombaugh region, creating a circular higher pressure zone. Elsewhere on Pluto the atmospheric pressure and temperature may not allow Carbon Monoxide to crystallise out as a solid, it remains as a gas in the atmosphere or is lost to space.

This postulated static high pressure zone must surely have an affect on atmospheric flow from hot hemisphere to cold. Would the flow be forced around the outside or through it, or would the higher pressure mass of gas start to spin?. Would warmer saturated "air" on reaching the higher pressure, deposit the various volatiles around its edge in the order dictated by their triple/freezing points, starting with the least volatile? Higher amounts of Methane ice on the Northern edge might be indicative of this. It is by no means the only explanation for Methane ice in this location. The climate is already looking anything but stagnant.

Earth's liquid oceans are intimately linked via a phase transition to the transport of latent heat around the planet in combination with heat transport in ocean currents. There is a single phase transition on Pluto, solid to gas and heat is transported around Pluto through latent heat exchange during deposition and sublimation of ices. The ices are just frozen atmosphere. Although at a much slower rate, heat can still travel through the surface ice, by convection and conduction.

It might not be a coincidence that Tombaugh Regio lies inside what l think is an impact basin roughly 800km wide.
Click to view attachment
Pluto is differentiated and likely to have layers of different volatiles at various depths. Here the impact penetrated deeper than anywhere else in the equatorial zone. Liquids filled the void, flowed south and carved a shoreline. Some of the nearby ropey terrain was eroded, leaving behind those craggy water-ice mountains surrounded by blocky debris. It's anyone's guess though, whether the surface CO deposits were laid down at that time or more recently.

It is a little sad that speculations on Pluto have been banished to an extraneous chit chat designation as opposed to a separate thread in the New Horizons segment. Regardless of data many of the forthcoming papers on the Pluto system will be informed speculation given the lack of definitive facts. For example, when did the Pluto Charon system form?

If as seems highly likely, Charon accreted from debris following a major collision we can safely state that this accretion would have occurred outside the Roche limit (around 3500 km for Pluto). The distance between Charon and Pluto now is 19,640 km but because they are tidal locked conservation if angular momentum means that Charon was once much closer. As separation increased there would initially have been major tectonic stresses gradually decreasing. Given Charon's lesser density and the fact that as the smaller body it would have become tidal locked before Pluto, the effects of tidal stresses on the surfaces of the two bodies would have been significantly different. If Charon was still reasonably close to Pluto tidal locking would have resulted in a tidal bulge that would collapse as distance increased resulting in something resembling a mountain in a moat. The tidal bulge for Pluto should gradually decrease until Pluto was also tidal locked without a residual bulge. Could Charon have received an external stimulus that resulted in the residual bulge being off centre? Could the final tidal locking been a recent event with residual tidal heat in the interior of Pluto?

Mike Brown (aka @plutokiller) had a couple of interesting tweets yesterday on the subject of Pluto being geologically active:

How long after the Triton flyby did it take until images with the geysers came down? Data rates weren't that much better from Neptune in 1989, were they?

That is interesting. The assumption I'm led to here is that in order to explain the lack of cratering that implies a youthful, geologically active surface, some other method is required, namely the redistribution of frosts / ices that is prominent enough to obscure the cratering-record. Add in the lower chances of collision in the E-K Belt and the much lower collision energy (1 to 2 kms^-1) then maybe frosts would do it.

But what of the atmosphere loss over time implying continual (or sporadic, ongoing) re-supply? Or are we seeing the last gasps and thin veneer of a primordial reservoir, however unlikely the odds?

I wonder how the water-cooler conversations explain these issues and which choice between geologically active and non-geologically active pleases Occam the most?

This is an interesting idea and I think theres a few elements that could lend itself to supporting it. However, I think the biggest reason this can't be the case is the lack of cratering. If that size of impact occurred, I would highly expect a ring system to form and as it condensed back to the surface, there would be many many impact craters. This would also deposit mixed elements across the surface and would leave few uniform looking areas, especially as large as Tombaugh Regio.

A palimpsest basin opposite the sub-Charon point is possible, given all that.

If we consider the Tombaugh region is the result of an impact, possibly from a de-orbitting moon, the energy and pressure during the impact is going to convert vast amounts of frozen volatiles for a short period of time into slush, liquid and gas that flows out of the impact basin. How far they flow would depend on their viscosity and how quickly they refreeze. This differentiation in their distribution should show up in the Alice and Ralph data more explicitly, but the lower resolution false colour images already gives a good idea that this is the case. I have borrowed Bjorn's excellent map to illustrate (see post 902 of the main NH Near Encounter thread).

https://www.flickr.com/photos/124013840@N06...eposted-public/

The green circle is the outline of the proposed impact basin. It is pretty obvious.

The purple outline shows the area of serious surface deformation and resurfacing from the impact event and it's aftermath.

The red circles show possible impact craters, which could be from secondary ejecta impacts.

The yellow area is the approximate area of Carbon Monoxide already highlighted by the team.

The blue lines outline the areas where other volatiles liquified during the impact have flowed away from the crater. (Roughly the pale blue/cyan coloured parts of the false colour image.)

A de-orbiting moon should hit very near the equator, but the tidally locked Charon creates a slightly deeper gravity well above the centre of the green circle and so this would slightly change the velocity of the moon and drag it just slightly north of the equator. Others might know better, but this small influence would only occur very close to the surface of Pluto, causing the object to scrape a South to North furrow just before impact, the cone of the ice cream. I have no idea if this sort of intuitive scenario is actually plausible, but thats my two cents worth.

Although I tend to favour the moon or large mountain sized impactor, I don't rule out the impactor being Charon either, scraping past the surface. It could be that only Charon's tenuous atmosphere actually contacted the surface initially to create the furrow and then a tiny patch, a few square kilometres, of Charon's surface actually contacted Pluto at the impact site, where the super heated atmosphere and flash sublimated volatile ices, cushioned the impact and "bounced" Charon away from the surface significantly altering its trajectory. I still have difficulty in believing that Charon was then captured, but there may be a small set of solutions that allow it, so I am still keeping an open mind until we see more of Charon's North Pole.

The curving scarps I circled would be the basin's outer rim. It is equivalent in size relative to Pluto that Mare Imbrium is to the Moon. Mare Imbrium also has an incomplete rim and no trace of inner rings, after being flooded with lava when the floor rebounded. Moderate-sized craters on Pluto can be made out despite having been blanketed under a kilometre or so of ice deposits, but there are none inside Tombaugh Regio. However, there appears to be craters west of that area that haven't been blanketed, particularly on the upper half of the whale's head. If Pluto ever had a thick atmosphere, there could be signs of its effects on the surface in high-resolution images of that region.

Yes, I can see a lot of tectonic changes taking place before the system became tidal locked but once tidal energy dissipated the surface should have been stable. While just one possibility, the mountain in a moat does does seem akin to the remnant of a collapsed tidal bulge. One thing I had forgotten and was reminded of in an old Dobrovolskis paper on the Pluto Charon binary system was that tidal dissipation would also cause the equatorial planes of the two bodies to realign to the [edit] orbital plane. The tidal bulge would become static as distance between the bodies increased but probably well before Charon became completely tidal locked, So after collapse it would potentially be displaced from the equatorial plane - just like the mountain in a moat. Yeah sheer speculation on my part but probably less speculative than geological activity or impact to explain the strange topography of the mountain in a moat. The upper bounds of the time taken for tidal locking for the system seems to be in the region of 100 Mya so the tidal locking is not in any way an indication of extended age and associated expectation of extensive impact craters.

Sad, but anticipated.

I didn't quite follow that Serpens, do you mean that tidal locking could have occured within the last 100,000,000 years and so the surface was being reshaped within that time, hence the surface is stable now and yet relatively craterless? That would place the formation of the Pluto/Charon system relatively recently, would it not?

I don't see this. There are so many example of large moons (half of the top ten KBOs by diameter have at least one) that for them all to be the result of a rare giant collision event is extremely unlikely. It's far more likely that large moons are a natural result of the KBO formation process in the low-energy environment of the outer Solar System, with each large KBO the "primary" of its own planetary accretion disc, from which large moons form in situ. Given the great distance from the Sun and the low planetisimal density, it seems likely that many of these KBO accretion discs would remain undisrupted until the large moons have coalesced (about half the time, going by the observed statistics).

All I am saying Marsbug is that if the Pluto - Charon binary system formed following an impact then the time from impact to tidal locking in the current configuration would have taken a comparatively short time in relation to the age of the solar system. When such formation occurred is an unknown but most of the surface features seen could readily be attributed to tidal and rotational deceleration tectonic processes and the lack of cratering does imply a reasonably short time since tectonics/resurfacing and dissipation of tidal heat. It actually doesn't matter whether formation of the system was due to impact or simultaneous accretion. The same roche limit, conservation of angular momentum considerations would apply.

Thanks mate, that's clearer. I agree.

Actually all of this is quite evident when you consider that the equatorial ice-field of Tombaugh Regio is an admixuture of variously CO2, CO, CH4, N2 or Ne and the organic refractory compound thiotimoline, which was likely introduced into the Pluto-Charon system by a passing Kuiper belt Chronoid body during the last age of Aquarius. By adding even trace amounts of thiotimoline to silicate minerals and refractory organics entrained in the gas flow, plus any desublimated dihydrogen monoxide also entrained.it allows workarounds around the various laws of Geology such as Uniformitarianism, Superposition and Superimposition. This get around some problems in the explanation of how younger strata can be emplaced below older strata. But since the exact properties of thiotimoline are not well-known under the conditions near this disputed planetary system, especially at the always-in-darkness cold trap in the South polar region, the actual effects on the geochron timeline is not well-constrained.

An idea of what could be found can be gained by reading "The Endochronic Properties of Resublimated Thiotimoline", I.Y. Ozimov, 1948, Campbell Press, with recent supplemantal material in http://danm.ucsc.edu/~phoenix/danm203/thiotimoline.pdf

Remember, there are no catastrophic processes, only catastrophic events. Sometimes things just go SPLAT.

--Bill

I, for one, would welcome a point-by-point rebuttal of the earlier posts within forum rule 2.1.

Hardly seems worthwhile mchan. Best to ignore the science fiction/fantasy world of Isaac Asimov's thiotimoline.

Following up on Dobrovolskis' paper led me to a collection of papers from various authors, speculating on the Pluto-Charon binary system. It was compiled by Alan Stern and published by the University of Arizona in 1997, simply titled Pluto and Charon. While dated the papers remain relevant and make fascinating reading. Some extracts are in Google books. Well worth the search for anyone interested.

Bill, you old rascal, excellent post.

I've inadvertently stolen this thinking in musings on the Pluto Near Flyby thread.

To develop it out a bit, there is a state of solid CO that packs a tremendous amount of physical energy when under pressure, and releases it explosively when the pressure is removed. The required pressure could only form very deep inside Pluto, but perhaps this condition was met. Then, a relaxation in the pressure could trigger a single, colossal explosion.

An impact might be the trigger. We also know that Pluto is venting stuff anyway, so maybe the integrity of the material that was providing the pressure crossed a threshold.

If any of this is true, one would expect it to happen, perhaps, only once in Pluto's history, so to have it happen very recently would be improbable, but not impossible.

I don't think it's inadvertently stolen, but I do like your line of reasoning on the CO / CO2 energy release of the phase change.





And add to this molecular gas ices and hydrocarbon ices and water clathrates all under alien conditions...

--Bill