[meteorite-list] Re: Entry Burn [was Lunar Burn]

[Mr EMan]

Welcome back, Walter

I'd like to point out that my original comment was
intended to "desuggest" copper in favor of nickel.  We
who have done blowpipe mineral studies tend to think
in that framework.

Several years ago on my farm outside Ft Benning,
Georgia I saw 2 nearly identical fireballs in the same
sky location but they were on adjacent nights. Both
were headed towards the Benning impact area, so I had
doubts as to their true identity. 

Most notable was that both showed a pressure/bow wave
clearly leading the dimmer fireball. The bow waves
were orange in the center with green wings.  Since the
sighting of two identical fireballs on successive
evenings is improbable, my inclination was that this
might be "secret" rail gun experiments.  The rail gun
fires a Lucite slug with copper plate. Ergo the
assumption that this was a "copper" blowpipe
signature.( I now believe that these were  true
meteoroids not weapon's testing)

Around that time there was a list discussion about
"green meteors" and the consensus was that green from
a meteor was due to nickel--copper being an extremely
minor element found in meteorites. Thus the origin of
that thought: nickel vs copper.  There was also a
lengthy discussion about the desire to do spectral
analysis on fireballs as a signature for identifying
possible meteoroid composition.  I hadn't heard much
since that time.

I don't disagree that oxygen has a green spectral
line, just that this was the first I heard of
atmospheric oxygen as an emmiter in fireball reentry. 
I rarely see green as a color in fireballs with some
Leonoids and the two specific fireballs I mentioned
before as the notible exceptions.

If anyone has specific links to the discussion of
meteor spectrums, please share.

Elton