Lasers and ICBMs (fwd)

From: Eugene Leitl (
Date: Wed Jul 25 2001 - 10:49:29 MDT

-- Eugen* Leitl <a href="">leitl</a>
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---------- Forwarded message ----------
Date: Wed, 25 Jul 2001 09:26:55 -0700
From: Tim May <>
Subject: Lasers and ICBMs

Being older than most of you, I remember doing some of these
calculations about burn times, laser intensities, etc. more than 20
years ago. (Although Reagan did not announce SDI until around 1983,
the topic was widely discussed in the late '70s. "Scientific
American" published articles by Prof. Kosta Tsipis, Richard Garwin,
and others about the difficulty of intercepting ICBMs with lasers and
particle beams. I remember some of these articles from circa 1977-79.
I even used one of the them as the basis for a presentation I made to
DARPA in Washington on a kill method for satellites.)

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
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.

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

I'm still skeptical, for the reasons many have outlined over the
years. Bill Stewart, most recently, who pointed out that the
Macedonian Liberation Army will simply smuggle in a bomb and then
demand that the U.S. and NATO stop arming the Albanian terrorists.
And so on.

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

--Tim May

Timothy C. May        Corralitos, California
Political: Co-founder Cypherpunks/crypto anarchy/Cyphernomicon
Technical: physics/soft errors/Smalltalk/Squeak/agents/games/Go
Personal: b.1951/UCSB/Intel '74-'86/retired/investor/motorcycles/guns

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