[meteorite-list] Re: Tektites

From: meteorites_at_space.com <meteorites_at_meteoritecentral.com>
Date: Thu Apr 22 09:43:31 2004
Message-ID: <20010714211907.23405.cpmta_at_c000.snv.cp.net>

Kelly Webb wrote after ">"

and Schoner replies:


>Hi,
 
> Glass's preliminary guess in 1968 that the Tunguska object had a
>"composition similar to that of tektites" has been long superseded by
>more recent and ongoing studies of the Tunguska microspherules, none of
>which bear this notion out. They are largely metallic, not glassy.

Probably, yes. I read somewhere that some of these might even be related to industrial activity and not the impactor at all. Billy Glass, a recognized authority on tektites made the statement, and I quoted it. But the jury is still out and I acknowledge it.


> The
>microspherules themselves lend no evidence either way on whether the
>impactor was meteoritic or a comet chunk. Actually more meteoriticists
>think the Tunguska Object was a stony meteorite, while more astronomers
>think it was a comet; it seems to correspond to whichever choice is most
>familiar to the theorist.

Whatever it was it was fragile. And having fallen on June 30th, and in the morning, it might have been related to the Taurid (?) meteoroid stream that the Earth passes through at around that time. I am not sure if it has been correlated with a comet or an asteroid. But it does seem coincidental that it fell at that date, and during a time of each year when large fireballs are likely to be seen.
 
 
> The crucial issue in the possible airburst of an impactor is the
>point at which the dynamic pressure of the atmospheric resistance [p =
>0.6 x gas density x (velocity)^2] equals the crushing strength of the
>impactor material. The Tunguska object, whatever it was, exploded at a
>dynamic pressure of about 200 bars. Whatever it was, it WASN'T weak and
>fluffy. That doesn't necessarily mean it wasn't a cometary fragment. We
>don't know enough about comets to be sure.

And we don't know what the effect of impacts to their structure and composition will be either. I would assume that they would, because they have been hit, and are being hit by other cosmic debris, that their composition would reflect that. But more importantly, how will such impacts while they are out in space affect the cometary structure? How fragile will they be after all of that bombarment? And how will they stay together when the do enter a planet's atmosphere?

Questions not easy to answer.

What we do know is that some comets are very fragile, and they break up by Solar wind pressure alone.
 
 
> The weakest fireball objects burst at 0.1 bar, so obviously there is
>weak and fluffy material out there, corresponding to interplanetary dust
>with densities of 0.01 to 0.10 gm/cm^3. However, your assertion that a
>10 kilometer weak'n'fluff would never reach the surface of the Earth is,
>well, ridiculous. The factor in determining whether an object will
>suffer ANY decceleration in the atmosphere depends on the total mass per
>unit area of frontal surface of the object.


Maybe my assumption might seem ridiculous to you, but it is obvious that such may very well have happened as the tektites indicate. Impact (or impactor) products (tektites and microtektites) scattered over areas as
broad as 10% or more of the Earth's surface and-- not a trace of a crater?

And these strewnfield distrubutions cannot be supported by having been formed, and ejected from the moon to Earth?

Humm... being skeptical... something is wrong in this picture.

However, there are several tektite fields that do seem to be associated with known craters, The Ivory Coast tektites-- Bosumtui (sp), Moldivites-- Reis, and Georgia tektites-- Chesapeake Bay crater.

But the Indochinites are the most enigmatic, for they point to some type of atmopheric bursting event that liberated enough heat to vaproize the impactor as well as ground rocks, throwing them far and wide of the epicenter of the event.
 
 
> Once an object is big enough to have more than 1.057 kilgrams of
>mass for every cm^2 of frontal area, it's gonna reach the surface of the
>Earth with its cosmic velocity relatively undiminished. The dynamics of
>cometary impact are as well known as that of any other kind of impact.
>That 10 kilometer fluffball of yours is just as deadly a hazard as any
>other object with its mass and velocity, whether stone, iron or pure
>neutronium [kinetic energy = mass x (velocity)^2]. A cometary fluffball
>with the density of interplanet dust particles, if there were such a
>thing, would reach enough mass to punch through essentially unimpeded at
>the 500 meter size.


I do not dispute that objects of the size that produced tektites are cosmic hazards to the Earth. Tektites clearly demonstrate that. But the fact is that, if they were, as I am convinced that they are, terrestrial, and no crater exists then an atmospheric burst (Tunguska event) must be the culprit. And though I don't dispute your mathematical reasoning, you have not proved that such a "fluff ball" (such as are some comets that break up by Solar Wind alone) ABSOLUTELY, and without question MUST reach the Earth's surface even if its size be at or below 10 Km in diameter. I suspect that there are other factors to be considered, such as the angle of entry, the velocity of the impactor, as well as its composition.

Some years ago, I saw a very interesting abstract by a Russian researcher looking into the dymamics of the bolide that created the Tunguska event. His analysis of it, using computer and mathematical models incorporating data gleaned from hydorgen bomb tests produced very nteresting results. As the impactor broke up, according to him, it had a "cascade effect" In other words the breakup caused more break up, and it
progressed exponentilly in the span of a millisecond or less, so that the energy release was as equal to that of a hydrogen bomb explosion in the air(airburst), not only in energy release but in effect as well.

The key point in his analysis as I remember was the total energy released in relation to the time element of the release, and the medium (air) in which that energy was released.

His conclusion was that the impactor made a "crater" in the Earth's atmosphere rather than the ground. Though not a very large body, if this was so then impactors do not have to reach the ground to produce craters. "Craters in the air" is what can be produced by an impactor if the conditions are right.

IN the case of tektites, they are evidence of such events on a much, much larger scale than the 1908 Tunguska event.
 
 
> Ignoring the numerical coefficients, we have a factor here composed
>of density x diameter^3 / diameter^2. This reduces to density x
>diameter. Even a little simple arithmetic would have revealed that your
>fluffball would have a volume of 5 x 10^29 cm^3 and a frontal area of 8
>x 10^11 cm^2 and hence would have to have a density of less than 10^-13
>gm/cm^3 to be unable to penetrate the atmosphere, or in other words, a
>density essentially similar to space itself or a very good laboratory
>vacuum. So, in a way, you're right: balls of vacuum do not penetrate the
>atmosphere!


NO, NO, NO! I think you had better go back to the drawing board on that one. A cometary "fluff ball" does not mean a vacuum. Let me give you this analogy. I think that it is a good one and illustrates the point well.

Suppose that you take a bullet-- a solid bullet and fire it from a gun at a set velocity at a target composed of ballistic jelly. The solid bullet will penetrate deeply into it leaving a bullet track in its wake as it expends energy. It will either pass through, or come to a stop, but all the while expending its kinetic energy until it comes to a stop.

Now use one of the "stinger" rounds, of the same weight, but composed of a bullet made of tiny lead shot contained in a polycarbonate shell. This round will travel at the same velocity, and strike the ballistic putty with exactly the same amount of force and energy yield-- HOWEVER-- because its structure is not consolidiated it spreads out on impact and expends its energy much facter and closer to the impact point in the ballistic putty, and more importantly it does not pass through. The hole "crater" it produces is in the ballistic jelly, and the majority of its damage is inflicted at, or very close to the point of entry.
  
The amount of kinetic energy of both rounds is identical. What is different is how they expend that energy on impact with the target and this is related
to the *structure* of the round AND NOT its mass.

The same effect I think applies to cosmic impactors. Structure is what determines how they release their energy in the Earth's atmosphere. (And whether they even reach the ground). Most larger impactors as you pointed out will reach the surface, but even a stony object of the same size as those that do, but that is highly fragmented can explode in a Tunguska type event
in the Earth's atmosphere rather than on the ground.

What is the pressure of the center of an explosion as the blast wave radiates out? Correct me if I am wrong, but I read somwhere that in the case of nuclear airbusts at 60,000 feet, that such an explosion produces a very strong blast wave which then radiates out from the epicenter, and milliseconds after that, the dynamic pressure at the center of that super heated plasma fireball is *close* to a perfect vacuum. Then in the wake of the blast the air rushes back to fill the void. (Take note of the old atomic blast footage of the blast wave-- it radiates out, then a moment later rushes back.)

Huge, mega-Tunguska events also produce blast waves that are "exactly" like thermonuclear blast waves, but on a much, much larger scale. And this is why in the early 50's that Dr. Lincoln Lapaz and others though
that the Tunguska event was caused by an "anti-matter" impactor rather than a meteoroid expending all of its kinetic energy in the Earth's atmosphere rather than on the ground. At the time, and with the limited information and data that was available to them they could not grasp the dynamics of a meteoroid disrupting in a cascade of fragmentation in the Earth's atmosphere. To get an idea of this, imagine the thing
shattering instantaneously, and in so doing coming to a complete stop high in the air. All of the impactor's kinetic energy would be converted to heat, and infrared radiation, and visible light. Instead of making the release of such energy in the solid ground it does so in the air. There will then be a bright and very intense flash-- just as in a thermonuclear explosion. In this regard, Dr. Roddy and previous to that, the late Dr. Shoemaker both told me that the energy release dynamics of Tunguska type events, are "identical" to the energy release dynamics of thermonuclear airburst explosions.

IN this regard a mega-Tunguska event in the Earth's atmosphere would most certainly generate enough energy to "blow away the Earth's atmsophere" and create a virtual supperheated vacuum as the fireball expanded, and additionally, the wake of the fireball (its track through the Earth's atmosphere) would also serve as a "conduit" for any impact generated materials that would be ejected into space as the flanged Australaisian tektites indicate.

Study the dynamics of the Comet Shoemaker-Levy impactors to the planet Jupiter to get a grasp of the process. The impactors expoded in the Jovian atmosphere and the blast plume then went up through the bolides wake. So if such happened there, such could and most likely did happen here on Earth.

Tektites serve as the evidence of such events.
   
 
 
> But, hey, we knew that already. That's what the backs of envelopes
>are for. When we get these great notions, like, I'll bet there are big
>comets so fluffy they won't penetrate the atmosphere, we do the
>arithmetic first to find out whether it's in the ballpark (or even if
>there is a ballpark). This notion is a complete non-starter.


As I pointed out, Kelly. I am no "arithmatic expert" (spelling either), but I think that the basis of your calculations are wrong. If you start out with the wrong assumptions, you will get wrong answers.

The fact is that Tunguska type events happen. And in the case of the Tunguska event, with impactors that may very well be much more substantial in structure than most comets. And I think that if you go back and plug into your equations some figures that show angle of entry variables, velocity of known comets, and also factoring in suspected struture based upon ovservation of fragmenting comets-- I am confident that your arithmatic will show that such impactors DO NOT necessarilly HAVE to reach the ground just because they are large.

They produce their craters in the air, and close to the ground, but not so much in it.

And impactor solids, along with that from the ground that was vaporized or melted by the air blast is then blown far and wide over the surface of the Earth, as the tektites and microtektites are found today.


> As for Michael Pain's article answering my questions, it was Michael
>Pain's article that was summarized in the CCNet post which raised the
>questions for me. I repeat, the notion of an impact of this magnitude
>--- 10,000,000,000,000 tons of TNT equivalent --- having occurred so >
>recently and without leaving unequivocal and substantial evidence,
>obvious traces, is ludicrous.


Air bursts. Mega- Tunguska events, just as I explained, and as he explained could and most likely are the cause for tektites.
 

> It reveals the increasing intellectual poverty of impact dogma to
>require an impact of this magnitude to create the Australasian field and
>be unable to find any trace of that fresh hole --- 70 miles across and
>12,000 to 20,000 feet deep --- in Indochina or anywhere else.


Craters in the air. Try to grasp the concept.

A crater in the air with the bottom of it reaching, but not penetrating into the ground.

That is what I and others think created tektites. It is a process that apparently happens only very rarely on the Earth.

34 million years ago in what is now Texas, and about the same time for the Georgia tektites.

14 million years ago for the Moldivites

800,000 years ago for the Indochinites.

Oh, and I forgot the Ivory Coast tektites-- was that 6 million years ago?

How many ground impacts have happened over that span of time? Many more than that. So I think that "air burst" events that produce their "craters in the air" are not nearly as common as those events that produce their craters on the ground.

  
> You can't
>bury all traces of a crater 1/3 the size of Chicxulub in less than a
>million years. (Back to arithmetic: it would take depositation of 1-2
>meters of sediment per century to fill the damn thing in and bury it in
>so short a time.)

Again, Kelly, your assumption evaporates and has no validity when one considers that Mega-Tunguska events produce their Craters in the *air*.
 
And the dynamics of air rushing back to fill that void is the explanation for the distribution of tektites as they are found on the Earth today.

I repeat-- You won't find a crater for the largest tektite field because the crater was in the air, and not on the ground. The atmosphere was, as I previously said, "splashed away" by the impact event, vaporizing both the impactor and the ground close to the bottom of the atmospheric crater itself. The crater is gone, filled in by air returning to fill the void, and the tektites are left as the only evidence that such an event occured.


> And, tektites do not have the "composition" of terrestial rocks, any
>terrestial rock.

On the composition there is no disparity between terrestrial rocks and tektites. Water is virtually absent, and that is about it.

As I quoted, Billy Glass, (a noted expert on tektites) said as much. And others that I have spoken to that are currently doing research on the tektite problem have also said as much.

So....


> There is no match for tektites anywhere on Earth. Even
>if by "composition," you mean "bulk composition," there is no match.
>What you are referring to is a set of plausible hypotheses that certain
>mixtures of terrestial materials subjected to certain very extreme
>conditions might produce something like a tektite. It's quite possible
>that they're produced that way, but it's hypothesis, not proof.

I am glad that you can admit this, Kelly-- because that is most likely the case. The proof will come, sooner or later. But I think probably in the next ten years the question will be resolved.

And the answer will be that they are terrestrial impact products caused by "air burst" events.


> Go grab
>some rocks and a big electric vacuum furnace and cook me up a tektite.
>That I'll believe. That would be proof. It's been tried, by the way,
>many times, and nobody's ever succeeded in making a tektite. Unique and
>perverse little things, that's why they're so interesting.

Until the middle of the last century no one could create diamonds in the lab either. Man had an
understanding as to how they might have been formed
but did not have the tools to actually make them.

And to date, I don't think that anyone has been able to re-create the conditions that would occurr during an air burst Tunguska type event. Conditions at, or most likely exceeding a Tunguska event are required to
form tektites. We simply do not know enough about it, or the conditions of such an event to bring about the creation of tektites in the lab.

Just because we can't at this time re-create them, does not mean that we cannot come to an understanding as to the processes that created them.

This is what science is doing now, and the evidence is mounting that they were created in terrestrial impact events.

I must add, that I am not an "expert" on tektites. In the past I sided with Harvey Nininger in his thoughts that they came from the Moon. But in discussions with Dr. John Wasson and others who have spent many years in the field and the lab studying them, my opinon has changed.

(And I might also add, that Harvey Nininger's position changed, too. More than a decade after the Apollo Missions, and in one of the last conversations that I had with him, when the subject of tektites came up
he felt that they were not from the Moon as he had previously proposed, but as the mounting evidence at that time indicated from impact events to the Earth.)

We talk about speculation?

The fact of the matter is, and as I pointed out before, there is ABSOLUTELY NO solid evidence that they came from the Moon, and there is ABSOLUTELY NO solid evidence for a tektite parent body, and or meteoroids.

BUT-- there is mounting evidence for a terrestrial origin.

So, based on the information at hand, what conclusion can we at this time draw?

I think that the answer is becoming clear.


>The isotopic compositions do indicate that tektites are derived from
>a differentiated body with a secondary crust. But the Earth is not the
>only such body, only the one we're most familiar with.


Yes, that is where they came from-- The Earth after impact events to the Earth's atmosphere created them.

One piece of evidence that shoots all tektite meteorite theories, and Lunar origin theories down are as I originally proposed-- the very rare Stretch tektites.

After very luckily acquiring the one that inspired all of this discussion at the last Tucson Gem and Mineral Show and going back to the Macovich Meteorite room to admire it in a brief quite moment-- it hit me like
a revelation-- the significance of the is form in the tektite mystery.

Looking at it, and knowing the mystery, it hit me, it struck me in an instant as I saw it.

These are the "smoking guns" in favor of terrestrial origin-- for there is absolutely no way that such a form could have survived falling from the Moon or anywhere else in space passing through the Earth's
atmosphere at 7+ miles per'second.

NO WAY-- it is logically impossible. And Darryl Pitt's meteorites, in the displays around me, fusion crusted, and ablated were evidence as to what the atmosphere does to bodies traveling through it at hypersonic speed. The flanged buttion tektites, too. Even they, ablated as they are and directly related to and contrasting with the "stretch" form indicated what happens when such objects travel through the Earth's atmosphere at hypersonic speed.

One would really have to "stretch" logic as well as science to explain them falling from space and then arrive on the Earth and still retain that stretch form. And the extraordinary stretch tektite that I have in front of me at this moment, with stretched bubble holes almost touching the surface, and a few breaking that surface, show absolutely no ablation that one would expect to see had such an object formed in the vicinty of the Moon or space and then fell to
Earth.

Nor do I buy the notion that stretch forms were formed by a "tektite meteoroid" breaking up in the Earth's atmosphere. Distribution problems exist with that notion. For to spread them out in the known strewnfields as they are would have also created the "crater" on the ground that everyone seems to be looking for. Also in this regard, tektites are much stronger material than comets. A tektite impactor would would therefore have a much greater likelihood of reaching the ground than an icy, "fluff ball" comet that breaks up under the influnce of the Solar wind.

So, the bottom line, the final piece of evidence that shoots down all Lunar, and tektite meteoroid theories is the rarest of tektites-- the so called "Stretch" tektites. Where they are found, close to the epicenter of the presumed air burst event, and their condition, lacking ablation, speaks volumes as to the origin of these strange objects.

On Earth.

And if not, then I challenge one, anyone far and wide, to explain how such a form could be produced on any other cosmic body, other than the Earth, then fall to Earth at hypersonic velocity, yet still retain its form which was clearly, and beyond doubt formed at or very near its point of origin.

I repeat it again-- The "smoking gun" for terrestrial origin of tektites are stretch tektites, and I think that tektite researchers should closely examine these forms in their quest to resolve the tektite enigma.

Steve Schoner
http://www.geocities.com/american_meteorite_survey
 
Sterling K. Webb
---------------------------------------------------
 
Steve Schoner wrote:
 
Actually, virtually every question that you raise can be addressed in a
very interesting article found in METEORITE, Feb. 2001 Volume 7, No. 1.
"Source of the Australasian Tektites" by Michael Pain, p. 34-37, with
extensive references that if followed pretty much shatter the Lunar, or
the supposed "silicate meteorite" theory.
 
Then there is that abstract by Billy Glass, {Microtektites and the
Origin of the Australasian Tektite Strewn Field; Publications of the
Center for Meteorite Studies, ASU, May 1968, p. 19) where he writes
after doing a microprobe of Tunguska glass spherules sent to him by Dr.
Krinov "Thus it seems probable after this preliminary investigation that
some of the Tunguska material may have a composition similar to that of
tektites."
 
As Tunguska clearly demonstrated comet impact DO NOT have to leave a
crater. And being that they are composed mostly of ices (gas and water)
they will not leave much solids either. (the lack of a crater might be
like the old story-- the perfect murder weapon-- a blade of ice).
 
The dynamics of cometary impact is not known, and there are factors that
are not understood. First off we are not certain how solid a comet is,
and what range of structure they might have. These icy dust balls might
be so fragile that even a 2 or 10 km one could not reach the surface of
the earth intact, instead exploding in the air in a Tunguska type event.
 
This would certainly generate huge amounts of energy-- enough to blow
away the atmosphere to the ground, dissociate the hydrogen-oxygen bond,
and melt, if not completely vaporize source rocks.
 
Comets are the most likely source for the events that created tektites,
and we won't have the evidence for it until it happens again, or when a
sample return mission brings back a piece of a comet and the trace
elements match with those found in tektites.
 
But more importantly, sans water, tektites in and of themselves reveal
their terrestrial source as they have compositions that are identical
with terrestrial source rocks. This is especially true of the
microtektites.
 
The evidence for Lunar origin has evaporated, and the the evidence for a
tektite meteoroid parent body is non-existent.
 
Terrestrial, impact origin is being ever the more supported by the
evidence.
 
So-- who is it that is relying on "faith rather than reason" ????
 
Steve Schoner,
 
 
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Received on Sat 14 Jul 2001 05:19:07 PM PDT