We all know well enough by now the story of the Russian meteor. It was the biggest meteor since Tunguska.
It is called the Chelyabinsk meteor, but in reality its biggest flare occurred over a town called Yetluk/Etluc/Etluk (different spellings, depending on who is writing it). Yetluk is south of Korkino, which is itself south of Chelyabinsk.
I have two specific things to blog on, and I should have been blogging on one of them long before. I’ve got a bone to pick on that one.
But this post is going to be on the second one, one that just came to my attention and that has some ramifications of how we think about meteors. Maybe nothing major, but still, interesting to me. . .
Okay, let’s get started on that one:
Take a look at this video.
A negative image (for better visualization) from 0:26 shows a pair of fragments going off to the top and bottom. Then at 0:28 about five larger fragments shoot out to the left of the meteor (and possibly with some forward direction, too).
The fragmenting is quite visible. Apparently at least seven fragments, of good size, are shot out. I would expect most, if not all, of the fragments to come from the front surface, the one doing all the ablating. After all, it is the one most exposed to heating
The fragments seem to come off before there is a flare-up. But just prior to the fragments coming off there is some of what looks like outgassing. Apparently fragments large enough to see are not the only things shooting off. What we might call “dust” would also be driven off by the force of the air.
So, in thinking about it, I’d say the timing of the flares in this last video with the fragmenting also suggests that the flaring (perhaps ALL non-burst flaring) is possibly just new surfaces being exposed.and new volatiles being burned. Perhaps it.is not necessarily exploding (though some would be), but the exposure of virgin surface and the newly exposed volatiles suddenly being heated. Fragments, big and small, before breaking off have more than just heat acting upon them. They are also being hit by hypervelocity air, which is a LOT of force. As pieces flake off – from heat OR wind or both – this virgin surface becomes exposed. I think it is significant that in the video the fragments shoot out just before there is outgassing/flare-up.
I worked back in about 1990 on multi-layer hot-core co-injection blow-molding. That is a fancy was of saying the plastic was injected in several layers, then later on blown to its final shape; but also that the plastic had to be heated all the way to the nozzles so it would keep its fluidity and be manageable all the way through the process. I got to work on the R&D side of things, and one thing I got to do was to experiment with exotic plastics.
One of those “engineering plastics” was on with the name of polybenzimidazol (we will call it PBZ). It was sold to us with the claim that it was not a thermoplastic plastic (a single material like nylon or polyethylene), nor was it a thermoset (a dual-material plastic that doesn’t do anything until you blend the two). PBZ was some weird third kind of plastic. When heated a LOT, it didn’t melt, and it didn’t burn. It just sat there and, little by little, layers would flake off. The flaking was called “ablating”. Because of this ablating ability, PBZ was used on the nose cones of rockets. The nose cone would get red-hot, and when the outer layer (the front) of the PBZ would get hot enough, it would flake off – exposing a fresh new surface to the heat. So, they would just have enough thickness of PBZ to get through re-entry, and the materials underneath would be protected from the heat. Oh, did I tell you that PBZ is also a great insulator?
Do you see where I am going here?
I am making the case that – just like the PBZ on nose cones, the materials at the front surface of a meteor also flake off, exposing new surfaces to be ablated. Oh, nobody designed the meteors that way – it just happens. Yeah, iron/nickel ones will also melt off – probably in blobs. But the chondrite ones are not metallic. (Some are a bit of both.) The chondrites will char (as I understand it), which is basically one of the steps in flaking off. The PBZ also basically chars, making it more “friable” – less well cohering to itself.
Flaking and Flaring
So, overall, I have the (semi-informed) opinion that on non-metallic or on combination meteors the non-metallic materials on the front surface of meteors ablate and slough off, layers at a time. And I propose that the continuous flaring – in fact maybe ALL of the brightness we see – is the result of small dust-like pieces or large pieces flaking off and allowing new volatile materials inside the meteor to be exposed to the friction heat and the air friction itself. Like a blast furnace, the air is ramjetted and combustion/oxygenization keeps on occurring, as long as there is material to combust.
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Oh, and BTW, in the video the object in the rectangle is literally an airliner. The pilots later described what they saw. See video at http://www.youtube.com/watch?feature=player_embedded&v=ICXyMyXbyqg, if you can understand Russian.