HPM%SU-AI@sri-unix.UUCP (11/15/83)
From: Hans Moravec <HPM@SU-AI>
n048 1253 14 Nov 83
(ScienceTimes)
(Art en route to picture clients)
By WILLIAM J. BROAD
c.1983 N.Y. Times News Service
NEW YORK - A top candidate has emerged in the Reagan
administration's quest for a technology to defend the United States
from assault by enemy missiles. It would be smaller, cheaper and more
powerful than other futuristic devices put forward in response to the
president's ''Star Wars'' speech, an appeal eight months ago for the
nation's scientists to develop what he called defensive shield in
space. At the core of the leading candidate to perform that task is a
small nuclear bomb.
Known as an X-ray laser, the device takes the power of a nuclear
explosion and channels it into laser rods that emit lethal bursts of
radiation in space. According to scientists at the Lawrence Livermore
Laboratory in California, the birthplace of the device, clusters of
X-ray lasers could, for example, stop the entire force of strategic
Soviet missiles, currently some 1,500 strong. The lasers would
literally pound the rockets apart with powerful X-ray beams.
A presidential panel recently called on the government to devote
$895 million over the next five years to develop the X-ray laser -
more than it recommended for any other technology uncovered in its
search, as President Reagan put it, for the means of rendering
nuclear weapons ''impotent and obsolete.''
But skeptics abound. Will the device really work? Can systems to
locate speeding booster rockets and to aim lasers at them be accurate
and fast enough? And would deployment of X-ray lasers tip the balance
of terror that has kept an uneasy peace between the superpowers for
nearly a third of a century?
Even defenders of the X-ray laser say it poses serious questions.
''There are very few technologies in the history of warfare that have
been either totally offensive or totally defensive,'' said Dr. Paul
L. Chrzanwski, head of military evaluation and planning at Livermore.
''If you can shoot down boosters, it's equally plausible that you
could shoot down satellites.'' The Livermore atomic scientists, add
however, that an examination of the device, to the extent permitted
by rules of government secrecy, reveals a unique technology that is
ideal for protecting the West.
What makes lasers so attractive for defense is their tight,
pencillike beams of coherent radiation, waves of electromagnetic
energy that move in step with one another. Laser beams can bore
through metal and bounce off the moon. In contrast, a flashlight
produces a jumbled beam of incoherent radiation that spreads out
quickly and disappears in the night.
X-ray lasers, moreover, can efficiently tap the titantic energy of a
nuclear bomb. The energy released in a single atomic reaction is
millions of times greater than in a single chemical one. According to
Livermore scientists, this makes X-ray weapons many times more
effective than chemical lasers, such as ones studied by the
Department of Defense that combine hydrogen and fluorine in a violent
reaction that can be made to create flashing beams of light.
The atomic potential is tapped when nuclear fire strikes the laser
rods - whose composition and design is secret - filling the rods with
energy and exciting their electrons so that they spin around the
nuclei of the atoms in expanded orbits. The fall of the electrons
back to their normal orbits - almost in a cascade - then creates a
beam of coherent radiation. If these electrons convert just
one-millionth of the energy of a megaton bomb - a minimum figure
often cited by the scientists - then each laser beam that emerges
from the device packs the punch of a ton of TNT, or about the energy
that recently leveled the Marine compound in Beirut.
X-rays would move toward their target at the speed of light. In the
split second before they hit, a missile would travel at most a few
yards. The burst of radiation would explosively evaporate the
booster's skin, launching a shock wave that destroys electronic
controls, rocket fuel and engine parts.
The distant rumble of the X-ray laser has been heard on at least
three occasions at the government's underground test site in Nevada,
starting in 1980. The beam from the first test was reportedly so
strong that it knocked out equipment meant to measure the radiation.
One of the inventors of the X-ray laser, Dr. George F. Chapline Jr.,
is a theoretical physicist who, sporting a corduroy coat with an open
collar, looks like the college professor he used to be. Every so
often his eyebrows come together in a look of puzzled wonder, as if
some apparently ordinary part of the universe holds secrets just
waiting to be uncovered. Last February the Department of Energy,
which finances the nation's nuclear weapons laboratories, gave him
its highest award, citing his ''highly creative applications of
atomic, nuclear and statistical physics to important national
security problems.''
An attraction of the X-ray laser, according to Dr. Chapline, is that
it can be used only in the vacuum of space and ''not against cities
and people.'' This is because X-rays, whose wavelengths are extremely
short, are quickly absorbed by individual atoms in the earth's
atmosphere.
But impenetrability is also a flaw, according to such critics as
Dr. Richard L. Garwin, an IBM researcher and Pentagon consultant. To
outwit the laser, he said in an interview, the Soviet Union needs
only to increase the rate at which its boosters burn fuel, so engines
are turned off and less vulnerable by the time they leave the earth's
atmosphere. The Livermore scientists dismiss this kind of criticism,
saying the precise power of the laser and the small divergence of
beams as they shoot through space - both measurements are top
national secrets - insure penetration deep enough into the thin upper
atmosphere to foil such tactics.
A key factor in favor of the X-ray laser, according to Dr. Lowell L.
Wood, a Livermore physicist and co-inventor of the device, is its low
price. He said each one might cost $2 million, half for the nuclear
bomb and the rest for hardware. In contrast, an MX missile costs
about $100 million. Low cost also lessens the competition's allure,
Wood said. Some of the large battle stations on the Pentagon's wish
list would cost between $2 and $5 billion, and boosting them into
space would cost an additional $100 million.
What all this means, according to Wood, is that the X-ray laser
would be smaller, cheaper and more powerful than other exotic
technologies. Small size is important, he added, because during an
attack the device could be launched into space at a moment's notice.
In contrast, bulky systems such as particle beams, chemical lasers
and electromagnetic rail guns often would need to be launched in
advance, and thus vulnerable to sneak attack while orbiting the Earth.
Praise for the X-ray proposal is anything but universal at
Livermore. Dr. Hugh DeWitt, a physicist who works on classified
projects, said X-ray advocates are biased because huge infusions of
money are at stake. ''There's lots of hype in the group,'' he said.
''The basic physics of the X-ray laser is O.K., but it's quite likely
that difficulties of system integration will defeat it.''
Moreover, some experts are skeptical on historic grounds, saying the
United States to date has spent about $25 billion in a futile quest
for an invulnerable defense. According to Dr. Herbert York, the first
director of Livermore, ''one of the outstanding delusions of recent
times has been the notion that a technological means for defending
the nation against a general nuclear attack is just around the
corner.''
Finally, critics say even a perfect defense would be a threat to
world stability. An aggressor might use X-ray lasers to knock out key
military satellites or, after a massive pre-emptive attack, to brush
aside a victim's feeble response. Indeed, that possibility worries
scientists at Livermore. ''Anything this country is doing along these
lines would be characterized as a defensive,'' said Chrzanwoski, head
of evaluation and planning. ''But I think that if the Soviets came up
with the same technology, I would be a little bit nervous about
possible offensive uses.''
The Soviet Union once had a large number of research groups that
published extensively on the theory of X-ray lasers, according to
Wood. But the reports suddenly dried up in 1977, leading to
speculation among atomic scientists that the Soviet program is now
highly classified.
Wood, a key spokesman at Livermore for the X-ray laser, is clearly
unmoved by the skeptics. He is a large, energetic man with a quick
smile and a steady eye. He answers objections with a patience that
bespeaks great confidence. The world is approaching a watershed, he
said. One X-ray laser, costing a few million dollars, will be able to
knock out a trillion dollars worth of boosters, radically changing
the economics of nuclear deterrence. He further insists that the best
way to avoid political instabilities - and, in fact, the ultimate
goal of the whole program - is for the superpowers to destroy their
offensive nuclear arsenals and replace them with defensive shields.
''The offensive approach to geopolitics is intrinsically unstable and
unsatisfactory and thus doomed to fail,'' he said. ''I'm worried that
when failure occurs, it will be catastrophic.''
nyt-11-14-83 1558est
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