As most everyone knows by now, the NASA/JPL’s New Horizons spacecraft passed by the dwarf planet Pluto six days ago. The images it has sent back are stunningly beautiful.
First off, Pluto itself (all images courtesy of NASA):
Notice anything odd about the surface? As in, what seems to be missing?
Craters. Lots and lots of craters. Thats whats missing.
Consider that Pluto lies at the inner edge of the Kuiper belt, an asteroid field probably larger and more populated than the more familiar asteroid belt between Mars and Jupiter. Consider also that most other non-gaseous outer solar system objects have surfaces that are generally heavily cratered, due to the accumulated impacts of smaller objects over billions and billions of years. The fact that craters are so few here indicates that Pluto’s surface is probably relatively new, only a few hundred million years old. Which means, Pluto is more geologically active than we originally thought. Some process is causing the surface to renew itself, either through active vulcanism or possibly internal heating caused by tidal stress from Pluto and Charon’s orbital dance (remember, Pluto appears to be composed primarily of various ices; it wouldn’t take much heating to periodically melt the surface into a viscous slushie).
Some close up views of Pluto’s surface have also been released.
Those are mountains, and they are composed almost entirely of water ice. They too cannot be more than a few hundred million years old, although it is probable that they are generally older than the smoother surfaces around them.
Moving on to Pluto’s principal moon, Charon:
Again, we’re seeing a general lack of heavy cratering, alhtough the surface here does appear to be more cratered than Charon’s parent planet.
Here’s a good image of the pair, showing once more their relative sizes:
The smaller moons of Pluto also recieved some attention during the flyby, but sadly they were all too far away for detailed images. These are probably the best images we’ll see for the satellites Nix and Hydra:
From what I gather, only about half of the data load that New Horizons recorded has been transmitted back to Earth. In fact, most of the really detailed images of Pluto taken during its closest approach haven’t arrived yet. New Horizons will be transmitting them over the next several weeks, so expect to see more images released in the coming month.
New Horizons will now fly on to another Kuiper Belt object, for an arrival sometime in 2019. There are two objects up for consideration, both of which are much smaller than either Pluto or Charon. A decision as to which of the two objects to target will be made in August, as New Horizons needs to start firing its engines no later than early September.
More details will follow as they become available.