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Shouldn't we be expecting a rock that has just been heated to plasma stage by atmospheric friction only seconds earlier to be glowing, steaming or leaving littl

Shouldn't we be expecting a rock that has just been heated to plasma stage by atmospheric friction only seconds earlier to be glowing, steaming or leaving little molten fragments of itself behind? Update: maybe not. The last stage of flight is "dark and cold" according to this: http://www.meteorite-recon.com/en/Meteorite_fusion_crust_1.htm http://www.meteorite-recon.com/en/Meteorite_fusion_crust_1.h...

deleted 13y ago
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jessriedel 13y ago
I imagine the rushing air can cool a rock pretty rapidly. The increase in terminal velocity will also tend to partially counteract the increased volume:surface-area ratio of larger rocks.
jccooper 13y ago
It has to be a pretty big rock to be hot when it hits the ground. Smaller pieces, on landing, are often found to be quite cold, entry heating not being long enough to remove the in-space cold soak, and the upper atmosphere being chilly.
goodcanadian 13y ago
As I understand it, the rock doesn't get especially hot. The hot surface ablates, and the rock underneath remains relatively cool (doesn't have time to heat up). From http://en.wikipedia.org/wiki/Atmospheric_reentry#Blunt_body_entry_vehicles http://en.wikipedia.org/wiki/Atmospheric_reentry#Blunt_body_... (admittedly about spacecraft rather than meteorites): "Through making the reentry vehicle blunt, air cannot 'get out of the way' quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward (away from the vehicle). Since most of the hot gases are no longer in direct contact with the vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere."
InclinedPlane 13y ago
Small rocks will experience substantial heating around their outside and will form a melt crust, but this cools down very quickly once the rock has slowed down. Most small meteorites are still cold in their interiors when they land.

deleted 13y ago

[deleted]

jessriedel 13y ago

I imagine the rushing air can cool a rock pretty rapidly. The increase in terminal velocity will also tend to partially counteract the increased volume:surface-area ratio of larger rocks.

jccooper 13y ago

It has to be a pretty big rock to be hot when it hits the ground. Smaller pieces, on landing, are often found to be quite cold, entry heating not being long enough to remove the in-space cold soak, and the upper atmosphere being chilly.

goodcanadian 13y ago

As I understand it, the rock doesn't get especially hot. The hot surface ablates, and the rock underneath remains relatively cool (doesn't have time to heat up). From http://en.wikipedia.org/wiki/Atmospheric_reentry#Blunt_body_entry_vehicles http://en.wikipedia.org/wiki/Atmospheric_reentry#Blunt_body_... (admittedly about spacecraft rather than meteorites): "Through making the reentry vehicle blunt, air cannot 'get out of the way' quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward (away from the vehicle). Since most of the hot gases are no longer in direct contact with the vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere."

InclinedPlane 13y ago

Small rocks will experience substantial heating around their outside and will form a melt crust, but this cools down very quickly once the rock has slowed down. Most small meteorites are still cold in their interiors when they land.