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Monday, 1 February 2016

Liquids on Pluto, its huge climate changes, and NH next target....

Recently Alan Stern spoke to the SBAG about the latest New Horizons plans (latest Adobe version needed). Alan is New Horizon's principle investigator (basically he's the closest thing an unmanned probe gets to a captain), Alan Stern. I was hoping to put up a youtube version of this talk, but the only version I can get my hands on needs the latest version of Adobe (gettable from here). For those of you who don't or can't get Adobe, here're the highlights of the talk, with some stills:

  • PEPSSI and SWAP instruments made important detections, there's a paper about it submitted to science magazine.
  • The dust detector will be the first to take readings out to 35 AU and kuiper belt
  • 16 months to beam all data back (4 months if they had the dsn to themselves)
  • They got good data on all of daylight Pluto, not just the side that got imaged at closest approach:
    • Black and white optical data of far side at 40km per pixel resolution.
    • UV and colour data, with 200 km footprint, of the far side - good enough to do regional colour and composition analysis.
    • The best resolution of encounter hemisphere is 70m/pixel.
Above: All the sunlight views of Pluto. Only the south pole was never seen due to permanent darkness.

  • New horizons has revealed a very complex world
    • Young icy plains - especially the glacier sea of Tombaugh regio.
    • Sublimation pits in the glaciers
    • Dark, very red, plains devoid of volatiles
    • Tectonic features: Scarps, faults, and rift valleys.
    • What look like shield volcanoes
    • A complex atmosphere

  • The atmosphere shows:
    • Possibly evidence of huge pressure pulses on the surface, from near zero millibars up to 100 millibars of atmosphere (more on that below)
    • 24 plus haze layers, probably made of tholin particles, up to 230 km height.
    • Very similar to Titan's extended/detached haze layers
    • They're blue in colour ,as seen from behind the planet via scattering via Raleigh scattering. 

    • The scattering is so bright the NH team can use the hazeshine to see the night side at high resolution, and are mapping large areas that way- an unexpected bonus!

    • Atmosphere is colder, and more compact, than expected - this result is from the by solar UV occultation experiment.
Above: The results of the solar UV occultation test.

    • Atmosphere loss rate is 1000 to 10000 times lower than expected - much more like a planet than a comet, which was the expectation..

  • A false colour, dynamically stretched, view of the surface shows....
Above: A false colour, colour sharpened, view of Pluto.

    • Red stuff (almost certainly organic) fills the mountains around glacier sea.
    • The glacier sea fills an ancient impact basin
    • The mountains are water ice, and are chaotic in structure; They seem to float on an ocean of frozen nitrogen.
    • The mountains have snowcaps of methane.
False colour close up.

  • The glacier sea has no craters (so it's under 10,000,000 years old.
  • It has a 'cellular' pattern on its surface.

  • This pattern is most likely due to convection in the ice (it's warm at bottom, like boiling syrup or a lava lamp)
  • The glaciers are active, not preserved, and are seen to flow around obstacles
  • Pluto seems to have , or have had, a Nitrogen cycle like Earth's water cycle
  • The southern glaciers have pits:
Above: Pits in the glaciers
  • Some pits are 100 meters deep or more, and show very, very, black matter at bottom.
  • The pits have possibly have eaten through into a layer below the glaciers.
  • Dendritic channels on the surface MAY indicate that liquids flowed on Pluto's surface in the past
Above: Dendrite channels.
  • This would be evidence of huge pressure pulses on the surface, from near zero millibars up to 100 millibars of atmosphere.
  • Shield volcanoes on surface, 100km wide, with very few craters on surface, indicating they are under a billion years
  • Pluto has young, old, and middle age terrains - which means Pluto has been active throughout its history - where's the energy coming from on such a small, cold, world?
  • Charon may have stolen atmosphere from Pluto during high pressure pulses, freezing it into dark polar cap
  • Charon also shows a complex geologic history
  • Organa crater on Charon has an ammonia ejecta blanket, possibly indicating subsurface fluids at one point.
  • Several of the little moons look like two objects merged:
  • The next target didn't get a name because Jim Greene dragged his feet getting the naming contest going, so it's called (informally) 'Jim Greene'
  • It's under 50 km wide
  • NH will arrive there on the1st Jan 2019
  • NH will come close enough to do science on 20 KBO's

  • NH will measure the heliosphere phenomena much better than Voyager.
  • After Jim Greene flyby Nh may go into astrophysics mode - seek microlensing events from extrasolar planets, and doing dust studies..
  • Here are the preliminary science objectives for Jim Greene:

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