[meteorite-list] Re: Tektites IV (very short)
From: meteorites_at_space.com <meteorites_at_meteoritecentral.com>
Date: Thu Apr 22 09:43:32 2004
On Tue, 17 July 2001, Kelly Webb wrote:
> Hi, Steve and List,
> On the problems of fragmenting a large comet (10 kilometer) into
> smaller enough pieces that each will airburst: The largest ice object
> that will airburst is about 100 meters. A 10 kilometer comet has the
> volumetric equivalent of one million such objects, so first we have the
> problem of how do you break it into 1,000,000 pieces?
> Separation speeds between fragments are about 1 meter/sec. Despite
> the high velocity, the low speed of separation is due to inertia. Total
> flight time through the atmosphere for a large object is going to be 10
> seconds or less, so the 10 kilometer comet is only going to swell into
> an 11 kilometer swarm of a million objects, if it can be fragmented.
> So, another way of phrasing the question is: How many seconds will
> it take to fragment a 10 kilometer comet into a million pieces? It takes
> the direct physical application of force to fragment an object. Even
> after a portion of the 10 kilometer comet has begun to fragment, how
> much time will elapse as that force is propagated through the 10
> kilometer thickness of the body? It's a question of sheer size versus
> the time alotted.
> A comet travelling at 30 km/sec and coming straight in has only 3
> seconds of atmospheric transit; at a low angle, perhaps 10 seconds. The
> body of the comet itself is so large that if one edge were touching the
> surface of the Earth at sealevel, the other edge would be higher than
> Mt. Everest!
> I can see the notion of cascade fragmentation, and of course the
> airbursting of the leading edge fragments would accelerate the process.
> But with the density of ice (1.0 gm/cm^3), there's 200 billion tons in a
> 10 kilometer comet. That's a lot of material to be broken up a million
> ways from Sunday in just a few seconds.
> Sterling K. Webb
Again, and again, as I have stated in detail before, Web is dealing with a model that does not take into consideration factors that would allow for a comet traveling at the highest possible velocity, and at an angle that would allow for an cascade distruption as in Tunguska resulting in a mega Tunguska event or a multiple of such. The model is faulty because it makes assumptions that are clearly not in line with certain facts that the tektites present us with.
The Australites in particular offer a distribution pattern covering at least 10% of the globe that is consistent with that produced by an airburst event-- an event of tremendous magnitude. And the microtektites associated with it also support it. This coupled with the fact that there is no clearly defined crater (100+ km) leads us to *what* conclusion? Impact products, (splash forms, propeller forms, aerodymamic shapes, teardrops, layered types, and stretch forms) all layed out over the earth in patterns cosistant with those that one would expect with an impact event-- but no crater. Craters in the air. An airburst event is the ONLY conclusion that one could draw from this. There is no other conclusion.
And if it conflicts with the model that Webb says that precludes this possibility then perhaps one must examine that model more closely to find out if there are factors that are not taken into consideration that WOULD allow for mega Tunguska events involving large up to 10 km comets of fragile composition exploding in the air-- producing the crater in the air rather than on the ground.
Lastly, tektites did not come from the Moon-- there is virtually no solid evidence to support that assumption. Tektites did not come from a cosmic tektite parent body-- there is even less evidence to support that than there is that they came from the Moon. AND finally, there is mounting and convincing evidence that they were produced in massive impact events to the Earth involving impactors, the nature of which we at this time do not fully understand. And in this regard, evidence has been found at Bose, China that seems to relate to the event-- shattered and burned trees and ground scouring 1,200 km from what is thought to be the epicenter in what is now Cambodia (Tonle Sap). But there is no clearly defined crater.
Bottom line-- Airburst(s) and the current models that would preclude this MUST fall short in some why, some factor, as of yet not recognized.
If so then current impact models DO NOT reflect reality. Steve Schoner.
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Received on Wed 18 Jul 2001 11:06:48 AM PDT