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Re: (meteorobs) Tunguska bolide & Beta taurid stream


jim>>There have only been three recoveries from the major photo networks:
Pribram, Innisfree, and Lost City, all of which were ordinary chondrites
produced by Type I fireballs from asteroidal orbits.  Ceplecha (Ceplecha
Z., 1988, Bull. Astr. Inst. Czech., 39, 221) in an analysis of photographic
and television data from multiple stations for 3624 sporadic meteors found
that 38% of fireballs come from cometary orbits (11% from highly eccentric
orbits typical of new comets), but most of the fireballs (62%) originate at
asteroidal orbits.  The standard explanation is that the denser asteroidal
material is more likely to survive an atmospheric transit than "weak"
cometary material.  <<

Thanks for the post....I thought for sure there were more than 3 recoveries 
from the major photo networks, but going thru FIDAC's reports I see there 
were a number that were photographed, but didn't see any mentioning of 
additional recoveries. I guess it just seemed that way from all those 
photographs? Wasn't the Peekskill meteorite's orbit also determined to have 
been asteroidal from the various video footage taken? 


jim>>a list of traits that they believe should be characteristic of a 
cometary-origin meteorite: 

1. Rare (as rare as carbonaceous chondrites)
2. Dark (about 5% geometric albedo)
3. Weak (~10^7 dynes/cm^2)
4. High porosity, low density
5. Highly unequilibriated Fe/(Mg+Fe) in silicates
6. Nearly Solar elemental abundances
7. High abundance of C, N, and organics
8. Anhydrous silicates
9. More likely than asteroidal meteorites to contain interstellar grains
with peculiar isotopic ratios
10. Likely not to have chondrules
11. Unremarkable cosmic ray exposure ages (~10^7 years)
12. and 13. Chemical differences due to cosmic ray exposure.<<

Would this almost be like the Carbonaceous Chrondrites without the 
Chondrites....or a pepsi without ice?
GeoZay

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