[meteorite-list] Further thoughts-Observations

From: Mr EMan <mstreman53_at_meteoritecentral.com>
Date: Thu, 20 Mar 2008 15:16:08 -0700 (PDT)
Message-ID: <564456.51498.qm_at_web51007.mail.re2.yahoo.com>

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


--- mexicodoug at aim.com wrote:
> Pete wrote:
> "Some will be blown up and some will be blown down."
>
> I believe this is a common misconception for many in the meteorite
> community and common thought. I don't think anything is "blowing
> up".
> Simply fragmenting. Each part of the original whole maintains its
> portion of momentum upon fragmentation. The direction of the
> momentum is along the angle of entry. There is no blowing up in that
sense of a bomb which propells fragments in all directions as there is
no internal source of energy (like in a chemical explosive).
Received on Thu 20 Mar 2008 06:16:08 PM PDT