[meteorite-list] Meteorites - warm or hot to the touch?

[Chris Peterson]

Jeff-

Ablation is indeed an extremely efficient way to carry heat away from an 
object. That's why ablative heat shields are the norm for craft designed to 
return to the Earth's surface.

Aside from that, there is the simple fact that heat transfer takes time, and 
there is precious little time available for a meteoroid to heat up. Take a 
big rock and put it in a 8000° environment for three seconds, and you aren't 
going to see much rise in the interior.

Oriented stones should be able to maintain supersonic or hypersonic speeds 
(but sub-ablative) for longer, so potentially could absorb more heat. On the 
other hand, they fall faster once they lose their cosmic velocity, meaning 
that convective effects are more efficient at removing heat. Not a simple 
thing to analyze!

Chris

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


----- Original Message ----- 
From: "Jeff Kuyken" <info at meteorites.com.au>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>
Sent: Monday, July 04, 2005 7:40 AM
Subject: Re: [meteorite-list] Meteorites - warm or hot to the touch?


> This is such a fascinating subject for which many theories could hold 
> merit
> and it's very interesting to hear them all. One thing that would lead me 
> to
> believe meteorites are 'generally' not HOT is the function of ablation. My
> rudimentary understanding is that it's not the meteorite itself that gets
> hot, but rather the super heated/compressed air in front. This in turn 
> heats
> the surface of the stone which is then immediately ablated away. I would
> assume that's why meteorite fusion crust is also comparatively so thin. It
> seems ablation is a very efficient way of removing heat/energy and there
> really might not be an appreciable rise in temperature throughout the
> interior. Obviously this would depend a lot on the size of the stone too.
> And the shape! I bet there would be a significant difference between 
> highly
> oriented meteorites and a "normal" shape.