New Horizons: Near Encounter Phase Options

[Habukaz]

but First Look B data was returned during yesterday's press conf. so which picture is that? what is the resolution?

The downlink completed during the press conference:

The times given are planned downlink end times.

The LORRI image we saw (of the mountains on Pluto) was probably early in the downlink queue for First Look B, so it could have been down many hours prior to the press conference (the entire downlink took 6.9 hours).

[fredk]

From the Heart photo & fredk's placement of the frame on it, it looks like the hummocks are caused by an impact crater just off-screen in the frame, visible at the bottom of the full disk image.

Right. And that makes the linear trough(?) that Explorer1 noticed (which runs diagonally through the hires frame) run roughly radially to the crater. No idea if that helps make sense of all this.

[Ken2]

Yes, but lines are often a further eroded stage (for mesas at least), and the bumpy stuff to the upper right of the arrowed mesa is typical of eroded mesa terrain. I think the black whale dusted region vs the white heart terrain transition is at play here - perhaps all the dark terrain is higher elevation capped terrain, and the heart is eroded - and this appears to be a transition zone. I think the biggest question of the mountains - where they pushed up or did the material around them erode/sublimate away? If it is due to erosion does it really take internal heat to do that over long time periods or are we just seeing a body sublimating away with dusty (maybe Charon dust) capped areas slowing down the erosion?

True, but I'm merely questioning your assertion that the darker "mesa material" has to be much harder. If it was much harder, there would be mountains around that had eroded off into points or ridges - but I would think they would be far fewer as once the mesa is gone, erosion would accelerate. The but the very low number of "mesa mountains" in this image seems to imply (to me) that that top material is NOT much harder - if at all.

Otherwise I agree.

I should have used a few more adjectives - I meant capstone in a loose earth analog sort of way - Pluto clearly doesn't have rain and doesn't need a hard crust, and I think it is a capstone only in the sense of an insulating dust/Thollins blanket which caps the sublimation - I doubt it is very hard, just insulating/protective. Since some sublimation would happen in less dusty/Thollinly areas - there would be half height mountains with some dark top coating. For the peaky already eroded Mesas - a dark residual coating on the sides of the mountains which fell down the sides as the white mountain material sublimated away would be expected and is visible in the pictures.

One thing that I wonder is the scientists assertion that it has to be water ice mountains to sustain an 11,000ft mountain - if the entire surface were packed frozen nitrogen (or something else) for instance and the base ground eroded - one can get taller structures via erosion then would be expected in a building process (again see the mesa remnants with their unlikely tall pillars). Hopefully we will have enough resolution to figure out the composition of the mountain slopes in the upcoming data.

[J.J.]

As someone who has been following a Pluto mission of some sort (first proposed, then actual) since the early '90s, I want to send out my sincerest thanks and congratulations to Stern and everyone else involved in New Horizons. As some others have already posted, I was too young to appreciate the Voyager encounters, so this mission has (and will continue to be) a source of unique interest and excitement. Again, bravo!

[pitcapuozzo]

New image of Charon, can't find the source yet.

https://pbs.twimg.com/media/CKDWGJKUkAAjcuQ.jpg

[Ken2]

...
I think the only major issue with the second hypothesis is how the other moons fit in. Are they leftovers from smaller impacts on Pluto that happened afterwards? Are they also captured bodies (Kerberos seems different from the other small moons at least). But either way, the trick now is to look at all the data and figure out which one is the more valid hypothesis.

Have they pinned down the exact orbital eccentricities and inclinations of all the moons? If not, they should be able to from the data they've got from the approach and flyby.

Here's a related question (which I don't know the answer to - someone must have modeled this): If an impact on Pluto created the smaller moons and they initially were out of Charon's orbital plane - would Charon's gravity eventually cause them to migrate co-planar (or get ejected), such that any long duration surviving moon by definition has to be coplanar? This would help add weight to the impact vs initial formation theories of Charon and the smaller moons.

[Habukaz]

New image of Charon, can't find the source yet.

https://pbs.twimg.com/media/CKDWGJKUkAAjcuQ.jpg

Looks like it's been taken down.

Edit: fullres of that version: https://pbs.twimg.com/media/CKDXE5iUkAACzu9.jpg:large

[Habukaz]

Here it is: http://www.nasa.gov/image-feature/new-hori...ntain-in-a-moat

More mountains.

[centsworth_II]

Now that is just weird. I don't recall ever seeing a mountain coming up out of the center of a canyon, rift, chasm, or whatever.

[Sherbert]

I thought I would take a closer look at that suspicious dark blob that Xflare and others mentioned. I've up sampled and zoomed the image so its a bit fuzzy.

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

Conclusion, probably not Cryovolcanic in origin, but there is lots of evidence of sublimation. A string of dark pits along the top edge and the right half seems to be shadow from higher ground in the centre. Although there are also dark pits on these peaks, they don't give me the impression of being Calderas or cones, just more sublimation hollows. Just a localised difference in dust/organics deposition I think, reflecting local differences in surface composition perhaps.

Top left of the image the light grey of the flatter terrain just intrudes and it can be seen to only partially cover the lumpy, pitted terrain, giving a "dune like" appearance. Many have commented about the "dunes" in the flatter grey areas. This is evidence that this is just the pre resurface terrain showing through the resurfacing layer. Being right at the edge of the tip of the Tombaugh Region, which is mainly Carbon Monoxide we are told, I suspect this is what has flowed over and resurfaced large parts of the area. By what process, is another story.

This extreme, though blurry close up does show how convoluted and pitted the surface is, much like the surface of a glacier on Earth, with differential sublimation, replacing the differential melting on a glacier. In places this forms long crevices and ridges, others mounds and pits. Next I am going to have a close look at that ropey looking terrain.

[Julius]

The fact we see craters on Charon reinforces the youth of Pluto's surface seen so far at high res.

[Habukaz]

First thing that struck me re moat mountain: deep sublimation pit/similar providing the path of least resistance to cryolava?

[volcanopele]

Nice to see a good example of flexure...

https://en.wikipedia.org/wiki/Lithospheric_flexure

[hendric]

My thought was an upwelling of heat that hasn't reached the surface, but softened it enough that the mountain pressed down, pulling down the area around it. Wouldn't have called that in a million years.

I suppose it could be a volcano, piling up and pushing down the area around it, but the borders look to well defined to me.

[MarkG]

Now that is just weird. I don't recall ever seeing a mountain coming up out of the center of a canyon, rift, chasm, or whatever.

An exaggerated case of isostatic adjustment, like the depression of the seafloor around the Hawaiian Islands? What pushed up the mountain went away, or we have volcanism. Definitely weird.