[meteorite-list] Further thoughts-Observations

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Thu, 20 Mar 2008 18:08:34 -0600
Message-ID: <00c701c88ae7$bdeccb70$0a01a8c0_at_bellatrix>

Hi Elton-

I don't see that any sort of explosion- especially not chemical- is
required to explain what you saw. There is a significant difference
between sending material in all directions relative to the point of
breakup, and imparting some lateral velocity. The former requires more
energy than can be reasonably explained- at least several times the
parent body mass in TNT. But it's certainly possible that with the right
sort of breakup (especially at low altitude), aerodynamics could produce
components that fly off the original path somewhat (but still with much
of the original forward velocity component). Combine that with an
expanding smoke cloud (where all forward momentum has been lost), and I
imaging a striking explosion effect. I see nothing about your
description of the Maryville fireball that contradicts this explanation.

In fact, videos of fragmenting meteors and of decaying space junk do
show components with some lateral velocity component. It's just not
common for that amount to be very much. Of course, if a fireball has a
large motion component towards the observer, the terminal explosion may
appear to radiate outwards in all directions even though all the
material is still traveling along substantially the same path.

We should also take care to distinguish between what might be possible
in exotic cases from what is typical. We all know that small meteors
don't reach the ground with hypersonic velocity. Well, except for one.
While we can't say for certain that there isn't a set of conditions that
might cause meteor components to be propelled from the parent at radical
angles and high velocities, we can say with absolute confidence that any
such event is very rare, and certainly doesn't represent a typical
fireball/meteorite fall.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message -----
From: "Mr EMan" <mstreman53 at yahoo.com>
To: <mexicodoug at aim.com>; <pshugar at clearwire.net>;
<Meteorite-list at meteoritecentral.com>
Sent: Thursday, March 20, 2008 4:16 PM
Subject: Re: [meteorite-list] Further thoughts-Observations


I have to respectfully disagree Doug. I'd agree more with you had I not
witnessed it myself. I believe there might be an unconsidered chemical
source to drive an explosion.

The Maryville Bolide(1983), which I was lucky to observe may have been
an aberration from the norm on several levels( e.g. calculations
indicate it was still incandescent between 3-4 miles when conventional
wisdom places the max altitude for incandescence at 5 miles above sea
level)but none-the-less it expanded explosively in all directions
formaing a slightly squat turnip-shapped fire/smoke ball. This
meteorite was likely still traveling 1-2 or more kilos per second when
it first appeared in front of me.

When it "bolided", there was a visible smoke trail of a fragment that
was ejected up and out at 45-60? leaving 3 distinct doglegs of smoke
trails as it went up, out, then started down. An area of secondary
crust was found on the only recovered mass suggesting that may have
been the source of the wayward fragment.

Many questions remained about this fall. Owing to an early morning
entry with both cosmic velocity and meeting Earth's 15kps(?) orbital
velocity combined, it was screaming fast. The size of the bolide/smoke
sphere was estimated between 400-1200 ft in diameter. This seems
rather large for the approx. 1kg stone which was recovered. The fall
was very close to a large lake so we could never be confidant if the
recovered stone was truly the surviving/main mass or if it was the
fragment observed ejected from the upper hemisphere of the bolide.

In that we know factually little and only weakly theoretically-- about
the actual expansion mechanism aka explosive disruption, I believe that
there is a case to be made for an "explosion"--i.e. rapidly expanding,
gas-driven, wave front which is moving at or near shock wave velocities
of chemical explosives or propellant burn speeds-- even if we are
unsure of the mechanism that expands the fireball to many diameters of
the original smoke/incandescent trail.

Be it recalled that when air suspended, combustible particles such as
coal dust or wheat flour are ignited, they act as explosives and can
collapse large structures or mine shafts. The nano-gram sized
particles of a extensive disruption when suddenly exposed to oxygen
might be a sufficient chemical explosive mechanism. For example,
metallic iron, shearing at apart at plasma temperatures, might be
literally burned in the higher oxygen levels of the lower atmosphere
and the rapid expansion of the fireball could be driven by a burning
iron fog--meeting the definition of explosive.

Regards,
Elton
Received on Thu 20 Mar 2008 08:08:34 PM PDT