Lasers and ICBMs

[Eugene Leitl]

On Wed, 25 Jul 2001, Tim May wrote:

> A lot of the calculations being sketched out here, of watts/cm^2,
> dwell times, gold coatings, etc. are slightly off-base. We've known
> for 20+ years that the kill method is to use a short pulse to "push"
> (not from the photons' momentum) in the thin wall of an ICBM's fuel

Explosive ablation sounds like giant pulses, and chemicals lasers (the
only ones known to provide lasing output in the ballpark) don't do these
very well. So either you have to fire synchonously from many platforms, or
have a veritable Death Star out there in LEO. Several of them, in fact, to
maintain an umbrella at all times.

> system. A very short pulse can produce enough ablative heating, a kind
> of "puff," to trigger buckling of the very thin wall of an ICBM.

During boost phase. Once past that, you need a kinetic kill or a nuke to
damage a nuke (largely, by neutron flux, not the momentum due to explosive
ablation).

> So the theory goes. Countermeasures to traditional "heating" are so
> easy to imagine (rapidly spinning the missile, deploying gold-plated
> shrouds once exoatmosheric, changing the missile coating at random

One would want to hide the real McCoys in metallized inflatable balloons
anyway, to hide them in the decoy cloud.

> intervals to foil laser frequencies, etc.) that the "punch" method
> was developed.

Gold or copper will do well for infrared, but aluminizing the hull will
still do for a wide spectral window, and I haven't heard about FELs
delivering the output necessary.

> For knocking out satellites, particle beam weapons are the way to go.

Do you think one could kill a hardened warhead in transit?

> And don't believe Kosta Tsipis' 1978-79 article in Sci Am about how 50
> loads of fuel in the space shuttle would be needed for every firing of
> a particle beam weapon.

It would be interesting to see whether any of the proposed solar power
satellites (which need realtime beamforming via a phased array to track
the rectenna target on ground) could double as vehicle killers, if
deployed massively.