I had located this paper titled
"Primordial N2 provides a cosmochemical explanation for the existence of Sputnik Planitia, Pluto". |
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While writing my Flopper page, I was struggling with the idea that the southern area of Sputnik Planitia (SP) was a deep large pit because I had read a paper in which Bill McKinnon had said the southern area of SP around Norgay Montes was shallow.
Because of this, I began questioning my conclusion which had been based on visual evidence that it was a deep pit. The concept of small cells around SP's perimeter helps support or validate my earlier conclusion that the southern tip of SP is deep, really deep compared to the rest of SP. This section of SP is also the central focal point of Charon's oscillating tidal bulge energy created as Pluto's axis wobbles 24 degrees. |
When I created the Flopper page, my reasoning for saying this southern area was deep started with the rubble pile of icebergs along the north western edge of SP. I figured if small rubble equals ground up ice bergs because of shallow N2 depth then larger rubble indicated deeper N2. This pattern repeats itself along the entire western edge of SP, the icebergs nearest the shoreline are smaller ground rubble ice block piles indicating shallower land. Larger rubble icebergs are further away from the shoreline deeper in the frozen nitrogen fluid. Down south at Norgay Montes the variance becomes massive with the 2.5 mile high ice berg mountains floating in the nitrogen ice. |
My premise was based on the size of grounded rubble which to me meant smaller ice blocks nearer the shore line equaled shallow fluid while larger blocks further out from the shore equaled deeper fluid. Without really even realizing it, I was also using the polygonal cell's size as an indicator of the existence of the large V shaped pit. The roughly "V" shaped area in red and yellow below has no polygonal cells bounded by troughs making this the single largest polygonal cell anywhere on SP also making it the deepest area by far indicated by the 2.5 mile high icebergs (Norgay Montes), |
I figured the depth of the large pit area had to be at least 3-10 miles deep in order to allow N2 to buoyantly support the above surface ice mountains without grinding them into small blocks.
Even if the icebergs are sitting on bedrock it would still have to be quite deep in order to avoid grinding these mountains of ice into smaller pieces. NASA suggests the deepest SP can be is 10 km or 6.2 miles. Their estimates are based on the diameter size of the polygonal cells as a function of them being formed by convection currents. I am, however, not convinced the polygonal cells are produced by convection currents. The largest quantity of "sublimation" pits exist along the perimeter of the polygonal cells indicating more heat also exists along the cell edges not its center. Convection would make the cell's center hotter than the edges with more pits in the center, this is not what we observe. I don't think the cells are formed by convection because the visual evidence suggests they are instead large sheets of floating water ice covered and bounded primarily by N2 and CH4. |
I waffled (wavered) a little bit on this idea but eventually settled on thinking the area surrounding Norgay Montes is deep not shallow. NASA (specifically Bill McKinnon) believes the Norgay Montes area is shallow similar to a beach. |
It also seems reasonable to assume this area is deep based on the fact this is the exact point at which Charon would induce a tidal bulge that is flexed and wobbled slightly as Pluto oscillates 24 degrees every 1.4 myr. |
As Pluto's poles wobble back and forth, it has to torque Charon and the small moons along for the ride. This creates a twisting lead lag oscillating tidal bulge stress focused around Pluto's minimum principal axis (MPA). This MPA is focused directly in line with the V shaped pit. Another possible explanation for why this V shape pattern exist is because the ices are more relaxed or more fluid in this area (its warmer). |
This paper says,
We find that bottom heated systems, as assumed by previous studies, do not produce surface planforms consistent with the observed pattern. We propose that the long-term variations of surface temperature caused by variations in Pluto’s orbit over millions of years produces secular cooling equivalent to internal heating. |
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In this map, the surface of SP is identified with various color coded characteristic traits. Bread Slice, Kilauea and a few other yellow areas are errantly identified as impact craters. The area that butts up against the Norgay Montes iceberg mountains is colored in teal green. This teal blue/green color is identified with the following trait, dpp which stands for deeply pitted plains. More pits equal more heat. Larger polygonal cells equal more depth. |
Here's the highest resolution image of Pluto I have.
Its 8,000 by 8,000 pixels, most are 5,000 by 5,000. |
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