[meteorite-list] How much survives entry?

[Chris Peterson]

To get a visceral sense of why so little material survives entry, we can do 
a simple back-of-the-envelope calculation that lets us ignore messy details 
like entry angle, composition, and ablation physics.

A very slow meteoroid (12 km/s) entering the atmosphere is carrying a 
kinetic energy of 72 MJ/kg. That's the equivalent of 17 kg of TNT per kg of 
meteoroid. Usually, all of that energy is dissipated in at most a few 
seconds (for our purposes, any surviving meteorites can be considered to 
have zero kinetic energy).

A meteoroid that enters at 26 km/s (still slow enough for meteorites) gives 
up 338 MJ/kg, or 80 kg TNT per kg.

Not hard to see from this just how rough a ride those meteoroids experience. 
The energy is what it is; the primary factor that determines survival is how 
long the energy is allowed to dissipate. That's why long lasting fireballs 
are much better candidates for meteorite producers than shorter ones.

Chris

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


----- Original Message ----- 
From: <cdtucson at cox.net>
To: "Richard Kowalski" <damoclid at yahoo.com>; "meteoritelist" 
<meteorite-list at meteoritecentral.com>
Sent: Thursday, December 03, 2009 9:32 PM
Subject: Re: [meteorite-list] How much survives entry?


> Richard,
> Very nice show tonight. I recorded it so I can watch again. You were very 
> very good!  You are (the) ultimate meteorite hunter. Congrats.
> I'm pretty sure it has been stated on this list that the amount burned up 
> in passage through the atmosphere depends on so many different factors 
> that any guess might be right.
> Anyway, Congrats again.
> Carl