GEORGE F. CHAPLINE
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away from a policy of nuclear deterrence. I would like to defer fur–
ther discussion of this question until the end . For the moment I will
simply assume that the motivation for considering defensive systems
is that many people would like to see a drastic reduction in the effects
of a first strike nuclear attack by the Soviet Union.
This brings us to the question of the technical feasibility of
strategic defense. Following the President's March 1983 speech, this
has been a subject of heated controversy in intellectual circles . While
a knee-jerk negative reaction to the President's speech from his po–
litical opponents was to be expected, the declarations of political op–
position were (and are) often accompanied by (and sometimes
camouflaged by) assertions that a defense against ballistic missiles is
not technically possible. Such assertions are in fact quite irrational in
the sense that one could not possibly know whether defense against
ballistic missiles is possible in the absence of a concerted effort to try
and make a workable defense - exactly what President Reagan pro–
posed .
The whole situation is reminiscent of the turn of the century
when it was widely believed in academic circles that heavier than air
flight was an impossibility. Actually, the problem of building an air–
plane at that time was mainly an engineering problem. Neverthe–
less, the Wright brothers had to build the engine for the first airplane
themselves, because no engine manufacturer of the day wanted to
expose himself to the ridicule of being involved in a project that was
well known in sophisticated circles to be crazy. There are good rea–
sons for believing that the problem of defense against ballistic
missiles today is mainly an engineering problem.
There are four technical developments that make the feasibility
of an effective defense against ballistic missiles much more plausible
today than it was in the 1960s when the question of a defense against
ballistic missiles also was widely debated. These are 1) the nuclear–
pumped x-ray laser; 2) the free-electron laser; 3) high-resolution
space-based telescopes; and 4) compact super computers.
The nuclear-pumped x-ray laser is a novel concept for directing
some fraction of the power produced by a nuclear explosion into a
narrow x-ray beam. Because the energy released in a nuclear ex–
plosion is huge, only a very small fraction of this energy needs to be
converted into a laser beam in order for the beam to have devastat–
ing effects over distances of thousands of kilometers. Because nu–
clear devices are relatively compact and lightweight, the nuclear–
pumped x-ray laser offers the hope of a space-based defense against
