[meteorite-list] Meteoroid/Asteroid Electro-Magnetic Disruption and Charge Properties?

[Chris Peterson]

A body larger than about a centimeter transfers its kinetic energy to 
other forms primarily by compressing the air in front of it as it 
descends into the atmosphere. The pressure involved is typically very 
large- tens or hundreds of megapascals for meter-class bodies. Once this 
ram pressure exceeds the material strength of the body, it breaks apart 
(presumably along existing fault lines, so the material properties of 
the body are important- and generally unknown).

Before the breakup, the heat created by compressing air is melting the 
surface of the meteoroid, resulting in ablation. This ablation is 
responsible for some of the light we see (along with atmospheric 
ionization from the same heat source), but is not particularly 
disruptive to the meteoroid. Only the outer surface is affected. 
Ablation is a very efficient way of removing energy (which is why 
spacecraft heat shields prior to the shuttles were ablative). When the 
meteoroid fragments at hypersonic speeds, however, additional surface 
area is instantly exposed, resulting in a rapid heating of the 
surrounding air (which is just a fancy way of saying "explosion"). If a 
body breaks into just a few pieces, as is common, we may see a central 
or terminal brightening. If it completely shatters into thousands of 
pieces (as seems likely with Chelyabinsk) the energy from the suddenly 
heated air is immense- an efficient conversion of kinetic energy to 
thermal energy. The expanding hot air can produce an impressive sonic 
wave, and probably further disrupts the meteoroid itself.

I don't that there are any electrical forces of a significant size to 
affect the structure or motion of the meteoroid, although atmospheric 
electrical effects probably occur (e.g. electrophonics).

Chris

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

On 2/26/2013 11:59 PM, drtanuki wrote:
> Dear List,
> If there is anyone willing to discuss the how and why meteoroids/asteroids "detonate" please explain for the list and myself.  I am interested learning more about the electrical/mechanical/physical forces that these bodies undergo as they reach the earth such as in the latest Russian event. Thank you.
> Dirk Ross...Tokyo