Cosmology Views

Pluto Round Craters

Pluto, like our Moon has round craters and some have a peak at the center of a flat floor with a consistent radius to the vertical wals around the circumference

Here is one image with several craters. Unlike any craters on the Moon, these walls have vertical striations.

first image has crater cluster

Some features have 'informal names' in this coarse resolution image, including several round craters.

second image showing features

third image from a distance

Though this post is about the round craters., other Pluto details are also interesting.

from Wikipedia:

The plains on Pluto's surface are composed of more than 98 percent nitrogen ice, with traces of methane and carbon monoxide. Nitrogen and carbon monoxide are most abundant on the anti-Charon face of Pluto (around 180° longitude, where Tombaugh Regio's western lobe, Sputnik Planitia, is located), whereas methane is most abundant near 300° east. The mountains are made of water ice. Pluto's surface is quite varied, with large differences in both brightness and color. Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as Saturn's moon Iapetus. The color varies from charcoal black, to dark orange and white. Pluto's color is more similar to that of Io with slightly more orange and significantly less red than Mars. Notable geographical features include Tombaugh Regio, or the "Heart" (a large bright area on the side opposite Charon), Cthulhu Macula, or the "Whale" (a large dark area on the trailing hemisphere), and the "Brass Knuckles" (a series of equatorial dark areas on the leading hemisphere).

Sputnik Planitia, the western lobe of the "Heart", is a 1,000 km-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal cells, which are interpreted as convection cells that carry floating blocks of water ice crust and sublimation pits towards their margins; there are obvious signs of glacial flows both into and out of the basin. It has no craters that were visible to New Horizons, indicating that its surface is less than 10 million years old. Latest studies have shown that the surface has an age of 180000+90000 −40000 years.The New Horizons science team summarized initial findings as "Pluto displays a surprisingly wide variety of geological landforms, including those resulting from glaciological and surface–atmosphere interactions as well as impact, tectonic, possible cryovolcanic, and mass-wasting processes."

According to the measurements by New Horizons, the surface pressure is about 1 Pa (10 μbar), roughly one million to 100,000 times less than Earth's atmospheric pressure. It was initially thought that, as Pluto moves away from the Sun, its atmosphere should gradually freeze onto the surface; studies of New Horizons data and ground-based occultations show that Pluto's atmospheric density increases, and that it likely remains gaseous throughout Pluto's orbit.  New Horizons observations showed that atmospheric escape of nitrogen to be 10,000 times less than expected.

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Pluto and Charon are in synchronous orbit , so Pluto rotates once in 6.4 days while Charon takes 6.4 days to orbit around Pluto at a barycenter distance of 17,181 km.

In other words they rotate face to face taking 6.4 days for once around.

I am surprised after only one fly-by, we can estimate the age of its surface and have even identified several 'processes' which resulted in this surprising surface, including 'obvious glacial flows.'

With Charon in synchronous orbit there is no periodic tidal force on Pluto's surface.

On Earth, glaciers flow by the accumulation of snow at the top so they, by their weight, slowly slide to a lower elevation by gravity.
On Earth, heavy glaciers can  have their sea-bound end  dragging and grooving the sea bottom.
On Pluto,  its glaciers are said to flow in and out of a basin.

The weak atmosphere is probably incapable of moving enough material to freeze onto glaciers so they get heavy enough to move by only  gravity.

On the image of Pluto features several grooves are shown. The 'obvious glacier flows' mechanism is probably needed  to explain grooves in the basin.

EU is not limited to erosion for surface features. Perhaps the grooves on Pluto are electrical scarring such as some canyons found on the terrestrial planets.

In our solar system where the gas giants are moving about, perhaps a more likely explanation is the smooth icy surface was deposited from a gas giant rather than the ice molecules moving around Pluto's surface within a very weak atmosphere. Nitrogen is in the atmospheres of Saturn and Titan.

NASA has described a possible return to Pluto mission arriving in 2046.