New Horizons Image Reveals Curious Corner on Pluto’s Icy Plains

Pluto’s Icy Plains from New Horizons

Transmitted to Earth on December 24, 2015, this image from the Long Range Reconnaissance Imager (LORRI) extends New Horizons’ highest-resolution swath of Pluto to the center of Sputnik Planum, the informally named plain that forms the left side of Pluto’s “heart.” Mission scientists believe the pattern of the cells stems from the slow thermal convection of the nitrogen-dominated ices. The darker patch at the center of the image is likely a dirty block of water ice “floating” in denser solid nitrogen, and which has been dragged to the edge of a convection cell. Also visible are thousands of pits in the surface, which scientists believe may form by sublimation. Click for full image. Credits: NASA/JHUAPL/SwRI

The latest New Horizons image reveals some intriguing surface activity on Pluto.

Transmitted to Earth on December 24, this image from the Long Range Reconnaissance Imager (LORRI) extends New Horizons’ highest-resolution views of Pluto to the very center of Sputnik Planum, the informally named icy plain that forms the left side of Pluto’s “heart” feature.

Sputnik Planum is at a lower elevation than most of the surrounding area by a couple of miles, but is not completely flat. Its surface is separated into cells or polygons 10 to 25 miles (16 to 40 kilometers) wide, and when viewed at low sun angles (with visible shadows), the cells are seen to have slightly raised centers and ridged margins, with about 100 yards (100 meters) of overall height variation.

Mission scientists believe the pattern of the cells stems from the slow thermal convection of the nitrogen-dominated ices that fill Sputnik Planum. A reservoir that’s likely several miles or kilometers deep in some places, the solid nitrogen is warmed at depth by Pluto’s modest internal heat, becomes buoyant and rises up in great blobs, and then cools off and sinks again to renew the cycle.

“This part of Pluto is acting like a lava lamp,” said William McKinnon, deputy lead of the New Horizons Geology, Geophysics and Imaging team, from Washington University in St. Louis, “if you can imagine a lava lamp as wide as, and even deeper than, the Hudson Bay.”

Computer models by the New Horizons team show that these blobs of overturning solid nitrogen can slowly evolve and merge over millions of years. The ridged margins, which mark where cooled nitrogen ice sinks back down, can be pinched off and abandoned. The “X” feature is likely one of these—a former quadruple junction where four convection cells meet. Numerous, active triple junctions can be seen elsewhere in the LORRI mosaic.

Source: NASA

2 Comments on "New Horizons Image Reveals Curious Corner on Pluto’s Icy Plains"

  1. How can one not be impressed by all this.

    • Well if you consider that all we have discovered in this flyby was pretty much to be expected based on the 30+ year old Voyager 2 mission it’s pretty easy to not be impressed.

      Charon looks like it’s the missing sibling of the Uranian moon system. The features we see on Charon have all bee seen before on those moons.

      Likewise Triton the moon of Neptune, long thought to be a captured dwarf planet showed a lot of the similar land forms, but with the addition of active geysers shooting upward above plains of slushy nitrogen.

      Was it neat to see Pluto/Charon, sure.

      However they could have seen all they saw and much much more had they sent an orbiter to Neptune or Uranus, and spent about the same to get there, because both are massive enough to capture a small probe in an orbit around it. Pluto being so small meant only a flyby was possible.

      Then when you consider there is NO 2nd large object to visit after Pluto, it turns into a big disappointment.

      The mission was sold in part based on the team’s belief they’d find another large object the probe could visit after Pluto. Now they admit it was just a hope, and are settling for a small kiuper belt asteroid.

      All in all, it would have been better to send a similar mission to Uranus or Neptune. It would have provided much of the same data, but in greater detail due to the ability to establish an orbit around either.

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