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Posted: |
Mar 1, 2017 - 7:08 AM
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By: |
Grecchus
(Member)
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The talk covers pretty much everything we've picked up about Pluto ever since the encounter. There is some extra pre-mission history and other bits and bobs that may be of interest.
What I was pointing to in the reference above is that the edges of Sputnik Planum indicate some kind of flow took place. Binzel makes the point that it is not known for sure whether the glacial flows are concurrent over time (take place gradually all of the time), or a one-off event - which is to say that some event temporarily caused the ice movement but after a short period the flow suddenly stopped and what we see is 'frozen' in time. Given that I'm about as certain of my convictions as can be, I would maintain the idea it was pretty much a one-off event, because I think the entire region is indicative of an impact, more than likely with Charon, at the point in time they first became orbital dancing partners. I think Charon impacted Pluto the other side of the planet to Sputnik Planum and that a very sudden deceleration of the entire planet due to impacting Charon pushed the less solid matter inwards on the hemisphere opposite the impact side, generally towards the centre of the planet though more tangentially so. During the actual blow between the two bodies, the ices would have been pushed inertially inwards in just the same way you are pushed backwards in your seat when you accelerate your car - remember, the less solid matter would have had the momentum of the entire planet before impact took place and would tend to impel forwards in motion. The same thing happens when you take off in a plane - engine thrust being applied makes your body press into your seat. Although you are on the plane, you are not rigidly fixed to it, so the tendency is for your body to fall back behind the aircraft and you would feel that force until all the atoms in your body are travelling at the same speed as all the atoms of the plane - that is, until a sort of equilibrium returns. That would generate heat that never ever existed before and caused the underlying ices to expand, so they eventually spilled out over the planetary surface. The problem is confounding, because it is not terribly easy to work out the mechanics on that large a scale from so rare an impact event. Both Pluto and Charon would not have stopped dead in their tracks as the collision was not head on - rather they would have experienced a partial deflection from their original motions due to compressive forces on impact - a bit like two soccer balls travelling in the same direction but slightly converging flight hitting one another off centre. The surfaces of the balls where they come into immediate contact deform elastically for as long as they are carried by their original momentum. However, the balls gradually start to push one another apart and if they survive the impact, end up on slightly different trajectories to the ones they had prior to collision. It is the internal transmission of those forces and directed shock waves which I believe somehow formed Sputnik Planum. As to why charon didn't get smashed to bits in the process is something I couldn't even begin to fathom, however, I think the salient facts of the evidence points in this sort of direction. We really do need to see the other sides of Pluto and Charon asap!
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Posted: |
Mar 1, 2017 - 8:41 AM
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By: |
Grecchus
(Member)
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It's more of an idea than a theory. In fact, I think that idea is conformal because anyone with a basic, general physics background would come to the same sort of conclusion, based on what can be seen.
What I find so frustrating is that the actual scientific community is under the spell of the giant impact theory as espoused by Theia. The smaller of the objects has to be blown to bits while reforming in orbit around the larger object, but with parts of one embedded to varying degree within the other. Surely, most of the visible moons captured by the planets could not have been acquired in this manner? By far, most of them must have become slaved to the gas giants, for instance, via aerobraking - that is to say, contacting one another ever so slightly so they remain more or less intact, save some visible external scarring, but with the velocity of the smaller object being reduced via friction so as to make it a permanent satellite of the larger body.
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Posted: |
Mar 2, 2017 - 9:34 AM
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By: |
Grecchus
(Member)
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The dark band around Pluto is addressed in the talk. One can understand that quality science must be devoid of wild speculation and that careful thinking is required in providing official explanations for observed phenomena. Also explained is why New Horizons did not carry a magnetometer.
Nevertheless, to date, no one in an official capacity has cared to provide a possible large scale scenario to fully explain why Sputnik Planum exists. They talk about surface details and visible features. A giant impact scenario has been mentioned by several notable individuals, yet, the really bold ideas about how Pluto and Charon came to be as they are have never really been feasible topics for imaginative discussion. No doubt, all the good folks at SWRI discuss these things amongst themselves, yet it seems that they proceed ultra carefully when it comes to communicating facts to the general public because they can't afford to appear to be wrong about something, especially if it involves a fair amount of imaginative speculation. I think the achievement of getting a suite of instruments to Pluto and having the hardware up to scratch at the point of encounter a worthy goal. I just wish they'd let their hair down a little. 
One final point. The most important aspect of the Pluto system to me is how did two similar sized Kuiper Belt objects (one of which is believed to be the largest) get swept up into an inclined elliptical orbit at one and the same time? This is perhaps the most interesting aspect of the Pluto system. That two large, yet similar sized objects in the Kuiper Belt became confined to each other's quarters, and somehow managed to maintain their own identities in the process, is what sets them apart from anything else in the Solar system.
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