[meteorite-list] Ureilite ablation

[Chris Peterson]

Diamond combusts at a fairly low temperature, less than 1000 K, 
converting it to amorphous carbon forms. At typical meteoritic ablation 
temperatures, the graphites convert to gaseous products like CO and CO2. 
So I'd say that the nanodiamonds found in ureilites have no significant 
effect on the fusion crust at all.

A single diamond entering at meteoritic speeds wouldn't form a fusion 
crust, because it would combust into gaseous components leaving nothing 
solid to survive. A diamond a meter or more across (I wish!) might 
survive to produce meteorites, but I wouldn't expect an actual fusion 
crust at all, since there would be no melting, only combustion. So I 
think it would just have an amorphous carbon ash on the outside.

Meteor ablation temperatures can be above the melting point of diamond, 
but that melting can only occur in the absence of oxygen and at much 
higher pressures than are present around a meteor.

Chris

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

On 3/31/2013 4:56 PM, William Feek wrote:
> Hi All,
> Do the diamonds in Ureilites undergo ablation, and if so, what does the crust on them look like?
> If not, then let me ask this, can someone hypothesize about what they'd expect an ablated diamonds crust to look like?
> William