[ExI] Asteroid on track for possible Mars hit

Gary Miller aiguy at comcast.net
Sat Dec 22 22:31:38 UTC 2007

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?

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.  

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.

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?


-----Original Message-----
From: extropy-chat-bounces at lists.extropy.org
[mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of Eugen Leitl
Sent: Saturday, December 22, 2007 4:57 PM
To: extropy-chat at lists.extropy.org
Subject: Re: [ExI] Asteroid on track for possible Mars hit

On Sat, Dec 22, 2007 at 12:41:09PM -0800, spike wrote:

> Hmmm, ja, but I don't expect it to be much less than 100kg.  We need a 
> spherical plutonium core surrounded by high explosive with a damper 
> shell, next to a heavy hydrogen device.  For this application, I 
> expect it to exceed 100.

Even a Davy Crocket could be easily carried by a single grunt. 
Modern fusion devices are the size of a large orange/grapefruit.
You wouldn't need a damper shell, you'd want to flash the facing face of the
asteroid/comet into a thin layer of plasma; preferrably iteratively. I don't
know that the lowest payload would be (and if I knew, it would be
classified), but I'd hazard more like 10 kg, than 100 kg. I'd rather bet on
some 10 shots of 10 kg payload each rather than one 100 kg shot.

> We do, but it would need a combination ground based or space based 
> radar with ground guidance, combined with some pretty tricky endgame 
> guidance on-board as is done with the THAAD missile.  I expect the 
> entire package to be closer to about 400 to 500-ish kg, since you need 
> guidance propulsion, attitude control, antennas etc.

So you'd need guidance onboard. Still, 400 kg is not that much. 
> Ja we would need all of 10 km/sec methinks, but I need to do some 
> BOTECs to figure out how we would do this.  I think we would need to 
> get as close as possible to coming the exact opposite direction of the 
> rock, otherwise I don't know if our endgame guidance authority would 
> be sufficient for a hit with current technology.

We don't want a direct hit. We want a detonation some 100-1000 m during
flyby, so we'd get asymmetric ablation and deflection, instead of
fragmenting the sucker into hundreds to thousands of bolides-to-be. That
cure might be way worse than the disease.
> I doubt we could get out to the object, match its velocity and attempt 
> a soft landing (the required delta V is way too high.)  So the biggest

While not having your background, this is my impression as well.

> technological challenge might be how to detonate the device within the 
> time tolerance when the closing speeds might be in access of 20km/sec.  
> The precision needed to do this is tech we don't currently have.  At 
> 20 meters per millisecond, if the device detonates 10 milliseconds too 
> early, 200 meters might be too far away to do much.  A millisecond too 
> late and the impact destroys the device without detonating.

You'd need a pearlstring of successive detonations, not a single on-off bet.

Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
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