[ExI] Asteroid on track for possible Mars hit

[J. Andrew Rogers]

On Dec 22, 2007, at 2:31 PM, Gary Miller wrote:
> Is the goal to aim for the side and detonate soon enough before  
> impact with
> the asteroid to create a shockwave which pushes the asteroid enough  
> off it's
> trajectory without breaking it up?


You realize, of course, that hard vacuum does not constitute a working  
fluid.  Photons will be doing all the work here, a combination of  
ablation and light pressure.


> With conventional explosive shaped charges can be used to direct the  
> blast
> energy in one primary direction.
>
> Is it possible to do a shaped charge with nuclear or is that out of  
> the
> question due to the much higher intensity of the blast.


Intensity has nothing to do with it, the explosives operate on  
fundamentally different principles.  Shaped charges work by  
manipulating how the detonation wave moves through the explosive,  
creating constructive anisotropies that are then mechanically coupled  
to the target.  You can create anisotropies in the photon output of  
the nuke however.


> Also if the blast directly destroyed the asteroid and the resulting  
> small
> debris burnt up on entry into our atmosphere.
>
> Would the radioactivity created by the blast create a serious threat  
> when it
> burnt up in the atmosphere?


We did plenty of atmospheric nuke testing in the mid-20th century.  If  
that was not a serious threat, the posited scenario certainly is not.

J. Andrew Rogers