Pluto
Out of context: Reply #34
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9.5 years in the making.
http://arstechnica.com/science/2…
Since its discovery 85 years ago, Pluto has been nothing more than a tiny dot of light. Thanks to NASA’s New Horizons mission, this is no longer the case. After a 9.5 year, 3.5 billion mile journey, a spacecraft the size of a baby grand piano has revolutionized our understanding of the icy world. The first close-up images of the Pluto system are proving to be every bit as exciting as the science team had hoped. Principal investigator Alan Stern said in a media briefing today, “The Solar System definitely saved the best for last.”
With the data beamed down so far, everything we can now see of Pluto and its five moons is changing the way planetary scientists view these distant, icy worlds. Not only does Pluto harbor 11,000-foot mountains composed of frozen water ice, but its surface and the surface of its largest moon, Charon, are surprisingly devoid of large impact craters. This indicates to scientists that both bodies could be geologically active.
The mountains—thought to be no more than 100 million years old—are very young compared to the age of the Solar System, and their average height rivals that of the Rocky Mountains found here on Earth. It’s too early to determine how they formed, but their presence was a surprise to scientists. “This is one of the youngest surfaces we’ve ever seen in the Solar System,” said Jeff Moore of the New Horizons Geology, Geophysics, and Imaging Team (GGI) at NASA’s Ames Research Center in Moffett Field, California.
Mountains can be formed in many ways, and the team cannot definitively say how these came to be. But they can rule out tidal heating. There are no other large bodies near Pluto other than its largest moon, Charon, and since it is tidally locked with Charon, there is not a large heat exchange system between the two bodies. There must therefore be some other geologic process taking place.
Whatever provides the power, it could reshape the surface through possibilities that include geysers and or cryovolcanoes. Neither of these processes has been observed yet, but the team will be looking for evidence of them.
The latest data, released today, shows a zoomed-in view of a vast, smooth plain north of the mountains in an area unofficially dubbed “Tombaugh Regio” in honor of the man who discovered Pluto—Clyde Tombaugh. Moore went on to say, “This terrain is not easy to explain; however, the discovery of vast crater-less, very young plains on Pluto exceeds all pre-fly expectations.” The icy plains of Pluto seen in the image—unofficially named Sputnik Planum after the first satellite launched in space—resemble frozen mud cracks like we see here on Earth. This could be evidence for contraction of surface materials, like when mud dries and cracks, or even signs of convection below the surface. More data will be needed to tell.
The region is broken into irregular “polygons,” approximately 20 kilometers across; these are bordered by shallow troughs. Some of the troughs are filled with a dark surface material, while some harbor groups of hills. The hills could have been pushed up via interior processes, or they could be erosion-resistant features.