(meteorobs) More on the Norwegian meteorite

[Nikola Bilišskov]

Hunter, Robert wrote:
> We seem to be forgetting that a 'soft' object can expend nearly all of
> its energy in the atmosphere.  For instance, the Tunguska object
> expended far more energy than Hiroshima, yet NOTHING got to the ground
> (except a shock wave, and maybe some dust).  
>   
Let's see..
1. If metoeoroid body is carbonaceous or silicate porous stone, than it 
is probably completely destroyed during its flight thrrough the 
atmosphere. A terminal explosion is possible for that case. What one can 
find is just a micrometeorite dust;
2. If meteoroid body is compact stone, three scenarios are possible:
    (a) dissintegration with possible terminal explosion;
    (b) body can decelarate during its flight through the atmosphere. 
Sonic boom is possible in this case, but the sound will be produced in 
lower parts of the atmosphere, but before the body completely 
decelerate. Meteorite is also produced in this case, but it's momentum 
will be not big enough to produce impact crater;
    (c) body penetrate to soil with "cosmic" speed, and, in this case, 
crater could be formed. Also, speed of meteoroid will be hypersonic, so 
the sonic boom will be audible.
3. Iron meteoroid - very compact body, for which, if its dimensions are 
big enough to endure the pass through the Earth's atmosphere, 2(a) and 
2(b) scenarios are possible.

Off course, it will depend not only about composition, but also on 
entrance velocity and angle. Probability of meteorite finding is biggest 
in case of 2(b) and corresponding "iron meteoroid" scenario. In the case 
of 2(c), meteorite will be melted, so just its traces could be found.

Now, it should be seen, on the basis of eyewithnesses and other 
evidences, which scenario was predominantly probable in concrete case.

Best wishes,
Nikola