[ExI] Asteroid on track for possible Mars hit

[Samantha Atkins]

On Dec 22, 2007, at 4:52 PM, spike wrote:
>
>
>>
>> That way if the course correction is not sufficient then you still  
>> have a
>> mass to target and not a swarm of smaller chunks which could impact  
>> us in
>> multiple collisions...
>
> Ja, but it isn't clear to me what would cause the thing to  
> fragment.  The
> surface heats up and boils away violently.  I suppose individual  
> fragments
> could come flying off, but I don't see that as a major problem.

Doesn't it depend quite a lot on the composition of the mass?  Given  
that the vast majority of meteors break up to some degree in  
atmosphere I would think there is some worry of breakup from a high  
yield fusion explosion near it.   I would think this is even more  
likely the less uniformly dense the object is and partially depending  
on its primary composition.  A comet would be the most fragile of all.

>> Would the radioactivity created by the blast create a serious  
>> threat when
>> it burnt up in the atmosphere? Gary
>
> No the scenario I imagine would deliver almost no radioactivity to  
> the earth
> at all, for the radioactive particles continue flying into space on  
> the same
> trajectory as before the blast.  A tiny amount I suppose might imbed  
> itself
> in the rock itself and return to earth, but compared to the amount of
> radioactivity from all those nucular* tests, it is nada.
>

In the context of a massive rock headed our way that is a serious  
enough threat to justify employing major nukes to deflect it I doubt  
very much any residual radiation on the rock itself would rate any  
real concern.

- samantha