Starship Asterisk*

Pluto from above Cthulhu Regio

Explanation: New high resolution images of Pluto are starting to arrive from the outer Solar System. The robotic New Horizons spacecraft, which zoomed by Pluto in July, has finished sending back some needed engineering data and is now transmitting selections from its tremendous storehouse of images of Pluto and its moons. The featured image, a digital composite, details a surprising terrain filled with craters, plains, landscape of unknown character, and landforms that resemble something on Earth but are quite unexpected on Pluto. The light area sprawling across the upper right has been dubbed Sputnik Planum and is being studied for its unusual smoothness, while the dark cratered area just under the spacecraft is known as Cthulhu Regio. So far, New Horizons has only shared a few percent of the images and data it took during its Pluto flyby, but will continue to send back new views of the dwarf planet even as it glides outward toward even more distant explorations.

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Clearly has the look of ice, with fractures and infill. And more than one flow overlapping another. But what kind of ice? Anyone for Pluto on the rocks???

Could the white plains of Sputnik Planum be covered with frozen atmosphere? It is in the northern hemisphere and at the end of a long winter. Perhaps as it condenses, the atmosphere settles into the lowest areas before freezing out, leaving higher areas bare.

Maybe a simplistic view, but here is an explanation for the unusually smooth region.

If a comet strikes Pluto, the heat of the collision could melt the dirty ice of the comet which then could spread on the soil and quickly freeze.

Is that too simple?

Cheers,

Didier

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http://apod.nasa.gov/apod/ap011018.html

Explanation: Pluto's horizon spans the foreground in this artist's vision, gazing sunward across that distant and not yet explored world. Titled New Horizons, the painting also depicts Pluto's companion, Charon, as a darkened, ghostly apparition with a luminous crescent against a starry background. Beyond Charon, the diminished Sun is immersed in a flattened cloud of zodiacal dust. Here, Pluto's ruddy colors are based on existing astronomical observations while imagined but scientifically tenable details provided by the artist include high atmospheric cirrus and dark plumes from surface vents, in analogy to Neptune's large moon Triton explored by the Voyager 2 spacecraft in 1989. Craters suggest bombardment by Kuiper Belt objects, a newly understood population of outer solar system bodies likely related to the Pluto-Charon system. NASA is now considering a future robotic reconnaissance mission to Pluto-Charon and the Kuiper Belt which could reach the distant worlds late in the next decade.
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http://apod.nasa.gov/apod/ap070304.html
http://apod.nasa.gov/apod/ap950805.html

Didier.Besset wrote:Maybe a simplistic view, but here is an explanation for the unusually smooth region.

If a comet strikes Pluto, the heat of the collision could melt the dirty ice of the comet which then could spread on the soil and quickly freeze.

Is that too simple?

I'm not sure if anybody has looked closely at the dynamics of low speed, massive impacts. These aren't possible in the inner Solar System (except with asteroids, and rarely some moons), but with Pluto we can have collisions as slow as 1200 m/s, which means that much less energy is dissipated and we could see more melting (as opposed to the outright vaporization associated with hypervelocity impacts).

The problem is, liquid water sublimates very quickly in a vacuum, so whether it would flow to a flat surface over a large area is unclear. A variation on your suggestion would be that underlying rocky material is heated by a low speed collision, and remains hot enough to allow liquid water or ice to flow for an extended time.

If it was up to me I would vote Pluto back in as a planetary member of our Solar System!

Pluto is cooler than an ice cold one !

Is NH heading towards any particular star system ?

ta152h0 wrote:Is NH heading towards any particular star system ?

That depends on how you choose to define "towards", and how long you're willing to wait. (But its path was not planned to intersect any particular star system.)

ta152h0 wrote:Is NH heading towards any particular star system ?

I don't know about a star system, but they may have it's next target selected ...
http://asterisk.apod.com/viewtopic.php? ... 87#p247487

I've been saying for some time that many mountains on Pluto look like large slide blocks (think Heart Mountain, Wyoming). The isolated rectangular patch looks very much as if it moved away from the rectangular notch to its left, and the isolated peaks above it might have come out of the small notch on top of the rectangular piece.

Chris Peterson wrote:

ta152h0 wrote:
Is NH heading towards any particular star system ?

That depends on how you choose to define "towards", and how long you're willing to wait.
(But its path was not planned to intersect any particular star system.)

• New Horizons is currently in Sagittarius.

Thank-you for the update. I've been following this mission since long before the launch, and appreciate every piece of new data which is being shared with us.

One comment, meant as a helpful suggestion, and not a criticism: Can you please ask the young lady in the Youtube videos to slow down, so that native English speakers can understand her? I appreciate that she is doing her best, and thank her for her efforts.

What I assume to be the full text of the videos is in printed the poster's comments on the pages, and that really helps, but its a shame that most of the world audience is missing out on the work which is being put into making the videos. How much better these would be if the spoken words could be given at a comprehensible speed. There really is no need to cram so much information into one minute. Why not make two [or more] videos with a part of the information in each one?

American English speakers might have no problems with the videos, but I am native English, and I find the accent difficult enough to understand, without the high-speed delivery. Non-native speakers of English must find it very difficult to understand her. The viewers' comments to the videos confirm that other people really are having difficulty in understanding the interesting information.

Thank-you for taking this into account.

Looking forward to the next 500 [or more] days. We have much to learn about Pluto and it's neighbours.

This is an amazing image in its own right, but I want to point out something that is not mentioned in the caption -- there is clear visual evidence of an erosion terrace from a previously larger ice flow/body. We see such 'terraces' around the great salt lake in Utah, USA, but to see a very similar structure around an ice flow/body on Pluto is truly astounding!

r.w.b wrote:Thank-you for the update. I've been following this mission since long before the launch, and appreciate every piece of new data which is being shared with us.

One comment, meant as a helpful suggestion, and not a criticism: Can you please ask the young lady in the Youtube videos to slow down, so that native English speakers can understand her? I appreciate that she is doing her best, and thank her for her efforts.

What I assume to be the full text of the videos is in printed the poster's comments on the pages, and that really helps, but its a shame that most of the world audience is missing out on the work which is being put into making the videos. How much better these would be if the spoken words could be given at a comprehensible speed. There really is no need to cram so much information into one minute. Why not make two [or more] videos with a part of the information in each one?

American English speakers might have no problems with the videos, but I am native English, and I find the accent difficult enough to understand, without the high-speed delivery. Non-native speakers of English must find it very difficult to understand her. The viewers' comments to the videos confirm that other people really are having difficulty in understanding the interesting information.

Thank-you for taking this into account.

Looking forward to the next 500 [or more] days. We have much to learn about Pluto and it's neighbours.

I think the issue with the audio in the "Pluto in a Minute" videos, is that it has been heavily processed and compressed. I am a native English speaker, with a flawless international accent ... ... and I am well accepting of the American twang, but there were certainly a few parts of the audio that were hard to decipher.

And heeeeeeer's Tooooooony BENNETT!!!!!

"I left my heeeeaaaaart....on Planet Pluto....."

This is a great image...looking forward to many more.

:---[===] *

I've been pondering the origins of the vast ice sheet known as Sputnik Planum... My first inclination is to assume it forms much like the polar caps and glaciers of Earth, due to precipitation from the atmosphere. I've read that it's mostly frozen nitrogen, and Pluto's atmosphere is mostly nitrogen. If I'm not mistaken, the ice sheet is centered near the side of Pluto that constantly faces away from Charon, so it is closer to Pluto's equator than it's poles. Also, with Pluto's considerable axial tilt and inclined orbit, the poles as well as the equator can get fairly direct sunlight at times during it's orbit... so I'm not sure that the angle of solar rays would dictate where an ice sheet forms on Pluto, unless it's somehow related to an atmospheric circulation pattern that favors precipitation on the side of Pluto that always faces away from Charon. Further, there seems to be little evidence of "snow" accumulation a short distance away from Sputnik Planum (e.g. the dark "Cthulhu Regio" to the "south" of the ice sheet which is heavily cratered suggesting great age, but does not appear to have any "snow" or ice cover, or any signs of past erosion from past larger ice sheets). I'm at a loss to explain why atmospheric precipitation would be so localized over the eons... and it appears that Cthulhu Regio and some of the adjacent mountain ranges (Norgay and Hillary Montes) are higher in elevation than the ice sheet... if so, it's not as if it "snows" in the high elevations and the glaciers then flow down into the plains...

Which brings me to my second theory: note the large region of jumbled blocks of crust to the left of Sputnik Planum that sort of look like a giant ice floe with the bergs pushed together and then frozen in place. Note that the Montes to the "south" of the ice sheet also appear to be composed of large blocks of crust (water ice?). Further from the ice sheet, the crust is not broken up into blocks and craters are visible, suggesting a much older surface. Note the relatively smooth arc that the edge of the ice sheet makes with the older terrain, especially to the "north". Could it be that the ice sheet occupies a massive impact crater? Were the giant blocks of crust (the Montes and the chaotic terrain) along it's perimeter broken up by the impact and then frozen into place? Did the ice sheet form from upwelling / outgassing / eruption of material from deeper in the planet after the impact? Does the upwelling continue to this day, sort of like a mantle plume triggered by the impact (sort of like the formation of the Lunar Maria that fill giant craters on our moon)? Could this process be what continues to replenish Pluto's atmosphere?

Wow, I got all shivery over this last image. I can't wait to hear what the geologists make of it all. I've not been commenting here lately but that is only because I've been working hard catching up to everyone in terms of data sets in my own brain. Cutting down on idiot remarks from me. Loved the lecture series by Robert and I've been reading every Apod since day one.

Back to Pluto. I have always been fascinated by which craters (across the solar system) develop a central bulge and which do not. I understand that this is a factor of impactor size, density, speed and impact location. Note the edges of Sputnik Planum into the featured areas of Cthulhu Regio. Note, in particular, the medium small craters. See how some present with central "rebound" mounds and others do not despite the size and impact depth similarities. The craters with rebound hills seem to share similar locations and/or similar geology in their vicinity. Even failing that, I think they tell a tale of the geology of their locations at the time of impact. Then note the, how can I put it "softness" of the apparent surrounds of the craters with no rebound marks and those with. It would lead me to conclude that those craters occurred in softer areas that had a deeper, low density ice layer at the time of impact. Something flexible enough not to develop the needed compression to result in rebound after impact.

This fact should help date not only the ice field's age but also its evolution and chemistry. It would be my suspicion that these crater effects can help give us a chronology of the life of the Sputnik Planum, especially at its boundaries.

My mind is flooded with uneducated erroneous notions of what those smallish craters with rebound hills in the middle and those without are telling us. Does anybody have an actual notion; who could shed light on what these crater differences could be telling us? Or shall we wait for NASA's geologists to make more educated "guesses."

I appreciated the comments by triastro and Wayne Jepson, above.
I followed the "images of Pluto" link and found a nice blog I need to sit down and read.
I was struck by something I could only see in the highest resolution "detail" image shown there.
Frozen nitrogen snowdrifts ! Also, the one peak I got in my excerpt is shaded lightly in the image. Does it have nitrogen snow all over it? Or is it something else that is giving it that smooth, almost shiny luster?

The light colored ice of Sputnik Planum is rapidly evaporating into the near vacuum of Pluto's atmosphere. The ice is made up of methane and carbon monoxide, in addition to the nitrogen. This is where Pluto's rapidly escaping atmosphere comes from. The ice is soft. Cooling at the surface has triggered solid state convection, which delivers warm ice from below to the surface where it can evaporate. The convection constantly renews the surface and creates the pattern of irregular polygons on its surface. A lot of energy is being released. All this activity is recent. It hasn't gone on since Pluto was born. Little planet Pluto doesn't have that much energy in it.

Until recently the soft ice of Sputnik Planum was sealed under a protective crust. Something shattered that crust, perhaps an impact or perhaps just internal volcanism. So the mountains, such as the al-Idrisi Montes, near the edge of Sputnik Planum that look like giant jumbled up paving stones are exactly that. They are about 3 miles thick and up to 20 miles long. They used to cover Sputnik Planum's ice. Apart from Sputnik Planum the crust still covers the entire planet, as does the ice ocean underneath it. The crust is not uniform in thickness. After the section of crust at the heart of Sputnik Planum was shattered, warm soft ice flooded out through the hole. Since then ice has flooded out of the hole to cover large areas of surface in a series of different directions around Sputnik Planum before receding. Such a flood is flowing out over Pluto's surface to the north of Sputnik Planum, right now.

The ice from Sputnik Planum doesn't actually rear up and roll over the landscape in a giant tsunami, instead it appears that the crust sags allowing ice to flow over it until the crust eventually rebounds causing what ice still hasn't evaporated to flow back. The crust is regenerated by a rain of hydrocarbons created in the atmosphere due to solar radiation triggered reactions between the methane, carbon monoxide and nitrogen. The material of the crust itself may be something like tarry pumice stone.

This 'thin crust' interpretation is my own. There is still a lot of information to come from New Horizons so I might have to make corrections. Many others have different ideas.

--------------------------
My Pluto Geology Interpretation Blog
http://charlesastro.wordpress.com . . . . . . . http://twitter.com/ChasAstro

r.w.b wrote: One comment, meant as a helpful suggestion, and not a criticism: Can you please ask the young lady in the Youtube videos to slow down, so that native English speakers can understand her?

You can slow her yourself, it's youtube after all. Select the replay speed in 'settings' on the lower right.

Charles Astro wrote: This 'thin crust' interpretation is my own. There is still a lot of information to come from New Horizons so I might have to make corrections. Many others have different ideas.

The idea may just be your own but it helps me wrap my brain around what I'm seeing. As a working hypothesis, I think it is very good. It sure helps me understand more concerning my own observations of details that seem to contradict each other.

A queer place, we've got here. Something tells me it's going to get more queer before it gets more clear.

Why the name "Cthulhu Regio" (Region of Cthulhu)?

Why not the "real" name of the place where dead Cthulhu waits dreaming? "R'lyeh".

Not knowing the aproximate rate at which Pluto is impacted I can't guess how new the smooth region in the upper right is, but I am sure that in "Pluto time", this picture is like an undisturbed crime scene. The smooth field shows a low angle impact from a huge body, perhaps even Charon. The smooth impact zone terminates with a huge well defined, crescent shaped debris field, from which, empty channels eminate. There is an area in the lower right of the image, that may also be material cleared away by the impact. There are craters in the debris that seem to indicate the area must be older than the smooth area, but these lack the distinctive bowl-like form of impact craters throughout the solar system. They are likely caused by the re-impact of material thrown by the main impact.

Mountain-like features can also be explained by huge chunks of Pluto's surface, broken and bulldozed by the impact. I suspect that the dark cratered area, lower in the image, is an indication of the smooth area's character before the impact. The channels must have been carved by liquid melted by heat from the event.