Race for the high ground

In the name of defending the nation, researchers in New Mexico have destroyed a missile carcass with a beam of light. In New Jersey, they have built an electric cannon that uses in a single burst as much current as the city of Newark. At a New York Air Force base, they are trying to develop electronic eyes sensitive enough to spot nicks on warheads in the vast dark of space. It's all part of what one researcher calls ``splendid defense'' -- President Reagan's Strategic Defense Initiative (SDI), his visi on of developing a screen to protect the United States from nuclear missile attack. Critics say it is a pipe dream, one that might precipitate, not prevent, Armageddon. This series will not try to decide between the judgments of ``splendid defense'' and ``pipe dream.'' But it will explore the current state of technology of SDI and the options this now gives the US in designing its multibillion-dollar program.

What began as a seemingly offhand remark by Mr. Reagan in a 1983 speech is evolving into one of the key global issues of our time. It proposes nothing less than a complete change in the way superpowers think about nuclear weapons. It is a central force shaping relations between the United States and the Soviet Union. It perplexes, and at times peeves, America's European allies. It baffles Congress, divides scientists, and stirs the kind of passion in public more often associated with theological d isputes.

``I think this offers more hope to the world than anything else,'' says Secretary of Defense Caspar W. Weinberger.

Scoffs IBM scientist Richard Garwin: It will require ``a kind of magic spell that will turn warheads to dust.''

The SDI, popularly known as ``star wars,'' is not a search for a perfect defense. Disinvention of nuclear weapons is not possible. Neither can the United States turn itself into a giant domed stadium, the population safely inside.

SDI is instead a multibillion-dollar inquiry into the relative merits of imperfection. While a leakproof defense looks improbable, even critics concede that a screen could be built to stop some Soviet missiles. Thus the key questions related to technology and feasibility are: How well would such a system work? Could the US afford it? What are the specific options?

A close look at the President's SDI program reveals these points:

The next 18 months will be pivotal in determining SDI's future. Members of Congress and lobbyists say they will devote full attention to the system for the first time. The Geneva arms talks may determine whether SDI research proceeds full-speed.

Official SDI plans initially involve rockets, high-speed guns, and other kinetic-energy weapons, which depend on the energy of motion for their destructiveness. Lasers, particle beams, and other exotic weapons aren't figured to be available until the year 2005 or 2010.

Weapons will not be the most difficult technical problem of star wars. That distinction will go to the computers, to the communications, and to other support technologies needed to knit the weapons into an effective system.

If SDI's goal is something less than perfection, it is also something more than mere protection of individual US missile fields, the goal of earlier ballistic-missile defense programs.

Technology alone can't make missiles obsolete. An effective defense of the US population would probably require some cuts in Soviet offensive arms, say a number of SDI officials. This brings arms control into the picture.

Cost is emerging as a major point of contention in the SDI debate. Administration officials concede they must be able to build a shield more cheaply than the Soviets can add offensive weapons to overwhelm it. Critics and supporters alike agree that this will be one of the program's toughest challenges.

Mr. Reagan's vision of a world bristling with defenses against nuclear weapons is not a novel idea. It is the latest event in an on-again, off-again effort by the US to build barricades against nuclear weapons -- a process stretching back to the dawn of the Atomic Age.

``There's such a sense of d'ej`a vu to all this,'' says Gregg Herken, author of ``Counsels of War,'' a history of the nuclear age.

As early as the 1940s, atomic bomb pioneer J. Robert Oppenheimer urged the world to work on defense against his own creation, arguing it was a moral as well as strategic imperative. In 1958, startled by the Soviet launch of Sputnik, Secretary of Defense Neil McElroy ordered development of systems for shooting down incoming missiles. This led to Project Defender, a wide-ranging program that some analysts think was more ambitious for its time than SDI is today.

Many of Defender's ideas never went much beyond the chalkboard. One, Project HELMET, proposed planting giant howitzers near US cities to shoot clouds of debris at incoming warheads. Another, SAMBO, called for orbiting a ring of pellets -- in effect, an artificial asteroid belt -- over known Soviet missile fields.

Other Defender work proved more enduring. Some of the earliest research on beam weapons occurred under the program, as did development of nuclear-tipped interceptor missiles. The interceptors became part of the only US defense against nuclear weapons ever deployed. It was installed in the 1970s to protect missile silos in North Dakota, but later it was scrapped as too costly and ineffective.

In the end the US decided that no defense against nuclear missiles was possible with the technology of the 1960s and '70s. The destructive force of nuclear weapons was so great that only something approaching a 100 percent defense -- a historically unprecedented achievement -- would have any meaning. Even a few nuclear warheads that got through a screen would spell disaster. Offensive weapons had unchallenged technological primacy.

In 1972, the US and the Soviet Union codified this mutual vulnerability in the Anti-Ballistic Missile (ABM) Treaty, which prohibited development and deployment of nationwide ballistic-missile defenses. The US, however, continued low-level research into missile-defense technologies. This work went almost unnoticed for years until March 23, 1983, when Reagan's star-wars speech pulled it back into prominence.

On the surface, Reagan's speech seemed impulsive. In fact, it caught many of his closest aides by surprise. Underneath, however, it appears to have reflected a variety of forces: technological advances that suggested an effective shield might for the first time be possible; Reagan's dissatisfaction, like presidents before him, with today's uneasy balance of terror based on offensive arsenals; and personal appeals from advisers such as physicist Edward Teller, the father of the US hydrogen bomb.

``The Soviets have a monopoly on defense,'' claims Dr. Teller, rocking back in a chair in his office at Stanford University's Hoover Institute, stabbing the air with a finger for emphasis. He is referring to the antiballistic-missile system the Soviets have around Moscow.

What sets the President's initiative apart from earlier thrusts is its stress on space components and a ``layered'' defense system. Previous efforts were mainly concerned with attacking warheads during their terminal phase, when the warheads reenter the atmosphere and dive toward targets.

Star-wars weapons would attack nuclear warheads at four phases of their 30-minute trip from silos to US territory. First is the so-called boost phase, when a rocket rises through the atmosphere for three to five minutes. Next is post-boost, the 3- to 5-minute period when the warhead bus, which carries the guidance system, warheads, and decoys, separates from the booster and begins to cast off its warheads and decoys. Then comes midcourse, when warheads and thousands of decoys float through space for 15 to 20 minutes, before reentering the atmosphere en route to their destructive destinations -- the terminal phase.

In theory, each defensive layer could be somewhat leaky and still contribute to an effective shield. If each layer destroyed 75 percent of the warheads leaking though the preceeding layer, 4 out of every 1,000 Soviet warheads launched would actually detonate on US territory.

To accomplish this task, a varied arsenal would probably be used because not all weapons may be good for all uses.

For example, kinetic-energy weapons may travel too slowly for use in the all-critical boost phase, when missiles are easy to find and warheads and decoys are wrapped in one neat package. Beam weapons can suffer similar limitations. For instance, some particle beams -- which use streams of atoms or atomic particles accelerated to near the speed of light -- can't penetrate the atmosphere. So they may not work for boost-phase duty. Certain lasers could eat down into the atmosphere, given much more brightne ss than they have now.

Under current SDI thinking, an initial missile screen would consist of ``kinetic kill'' weapons, such as quick rockets. If deployed at all, such a space-based defense would likely not come about before the mid-1990s. Exotic beam weapons would not be ready until the turn of the century.

Of course, it is not a foregone conclusion that these weapons will work. Most are now only lab experiments.

And any weapon, however powerful, is useless if it cannot be plugged into a working system. More than anything else, this is the requirement that makes star wars perhaps the most complex military undertaking ever.

The star-wars system first must find its targets. This would be particularly hard in the midcourse phase, when warheads and decoys may number a quarter of a million objects.

Picking out warheads from the radar-spoofing chaff, Mylar balloons, and other decoys will require new ways of getting different types sensors to work together. ``I think boost-phase intercept and midcourse discrimination are the key issues for a cost-effective defense,'' says Cornelius (Cory) Coll III, head of an SDI study group at Lawrence Livermore National Laboratory in Livermore, Calif.

Once targets are identified, weapons must be aimed and fired, and kills assessed. This requires ultra-fast communications and perhaps the most ``intelligent'' computers ever made. Computer hardware can probably be made to crunch numbers fast enough, though this will take plenty of work.

``It'll be like putting a Cray supercomputer on a sugar cube,'' says John Bosma, editor of the newsletter Military Space. The computer he refers to can perform up to 1.2 billion calculations a second.

But writing the software -- the instructions behind the number-crunching -- may be the single most difficult task of the program. SDI officials say yet-unknown technological advances will help write the 10 million to 100 million lines of software needed.

Critics contend that software bugs could never be worked out of the system.

``You'd have to have a real nuclear war to have operational testing,'' says David Redell, a Digital Equipment Corporation engineer.

Some critics also complain that so many lightning-quick decisions would have to be made that humans could not run the system. SDI officials say a top military officer would watch over the shield. But they concede star wars will impose new challenges on how to bring political and military leaders into the decisionmaking process.

An even bigger concern: While the US is developing defensive weapons, the Soviets will undoubtedly try to devise ways to counter them.

``Technology today is capable of shooting down offensive missiles. The question is: Can you do it in face of what the Soviets do in reaction?'' says former Defense Secretary Robert S. McNamara.

The Kremlin might build more offensive missiles and warheads to try to saturate a defense. They might try disguises -- balloons imitating warheads or warheads hiding in balloons.

They might try to skirt a defense altogether by aiming submarine-launched ballistic missiles so they leave the atmosphere only briefly, if at all, or by developing legions of ground-hugging cruise missiles and strategic bombers. These would be difficult to zap from space.

But SDI advocates argue that some star-wars weapons may work against this threat, and that, in any case, it is important to blunt the accurate land-based ballistic missiles, the heart of the Soviet strategic arsenal.

Moscow could also design ways to foil specific defensive weapons. They could spin boosters like drill bits so that lasers can't dwell on one spot, or devise thick-skinned missiles to resist attack. Perhaps most worrisome, they could build fast-burn boosters that would complete their work while still in the atmosphere, hampering the ability of some weapons to reach them.

Fast-burn boosters would be costly, both in reducing the performance of a missile and on the Soviet economy -- prohibitively so, SDI advocates say.

This type of measure-countermeasure gamesmanship will be expensive for both sides. ``You want to make the Soviets spend a lot of money,'' says one SDI scientist.

Finally, the Soviets could simply punch a hole in a defense system. They might orbit ``space mines'' that would blow up on command and shower satellites with shrapnel. One SDI scientist worries about three other antidefense weapons: ground-based lasers; nuclear-tipped interceptor rockets; and X-ray lasers, beam weapons powered by small nuclear bombs. The US is developing the X-ray laser as a possible defensive weapon, and the Soviets are known to be working on it as well.

``Many of these defensive technologies are the key to the destruction of the defense itself,'' Dr. Garwin says.

But battle stations may be able to defend themselves or have special ``guard'' satellites to do the job. They may be armored, or able to bob and weave when attackers approach.

``I worry about survivability. Along with cost, I see it as a major constraint to SDI,'' says Stephen Rockwood, head of SDI research at the Los Alamos National Laboratory in New Mexico.

Weapons in space might be used offensively to destroy an adversary's satellites. In theory, they might also be able to destroy aircraft or hit ``soft'' Soviet targets, such as factories. But SDI officials counter that star wars is only a defensive program and that soft targets can be more easily destroyed by existing weapons, such as bombers.

Whatever its final capabilities, any defensive shield would be expensive -- equal to adding another Navy to the budget, according to critic John Pike of the Federation of American Scientists. Estimates of a star-wars system's cost run to $800 billion or more, but until the system takes shape such figures are guesswork at best.

What is known is that expenses would not stop with deployment. ``Even in the absence of hostile action, there will have to be constant activity in space . . . to maintain a working system,'' notes a report by Congress's Office of Technology Assessment.

Star wars, after all, would be unprecedented in scope. It requires advances in basic science and engineering, and must take into account a cunning adversary who can shoot back. Work on the program may span 20 to 30 years. By comparison, during World War II the Manhattan Project to develop the atomic bomb took four years; landing on the moon took eight.

Even if it turns out that a defensive shield can be built, and for something less than a year's gross national product, there's the more fundamental question of whether it should be built.

According to President Reagan, star wars is a way out of today's nuclear balance of terror, in which the superpowers refrain from war because each is able to retaliate against the other. The balance of terror resulting from the primacy of offensive nuclear weapons has dominated the four decades of the nuclear era; and the specific American doctrine of mutual assured destruction (MAD) has dominated US military strategy for more than two decades.

SDI enthusiasts envision a world of ``assured survival,'' in which the US would once again control its own destiny. Under the most prevalent scenario, initial deployment of a defensive screen would deter the Soviets from launching a first strike, because they would have doubts about how many of their missiles might get through. In effect, this would strengthen MAD, though not replace it.

Over time, the Soviets would come to see the futility of investing in offensive forces and would begin to reduce their arsenals, relying more on defense. The world would never become free of nuclear weapons. But their role would be greatly reduced. They would be unusable and hence obsolete, in the words of one Reagan official. ``Obsolete and unusable, what's the difference?'' asks George A. Keyworth II, Reagan's science adviser. ``This idea of needing an umbrella of perfection is misleading, because you r real objective is to make nuclear weapons unusable.''

Critics see more dangerous endings to this script. They are concerned that development of a US shield will violate the 1972 ABM Treaty, unraveling the fragile fabric of arms control pacts. The response to US defenses will be a Soviet arms buildup, they claim.

Even if the Soviets decide to set up their own version of SDI, the transition to a defense-oriented world would be tricky. If one side developed a superior defense, it might be able to strike first with its nuclear missiles, knowing that its shield was good enough to handle any retaliation. Thus defenses might heighten, rather than lessen, the chances of nuclear holocaust.

Another conundrum is what a defense-dominated world would mean for America's European allies.

At present, Europe remains safe from the Soviet Union's massive conventional forces because of US nuclear might. If a Soviet defense shield neutralized this strength, Europe might once again be exposed to conventional war.

To the Reagan administration, SDI is an example of technology leading diplomacy toward a safer world. To critics, this vision could do more harm than good.

``It deludes the public into thinking that the solution to the dual problem of nuclear weapons and a troublesome adversary can be resolved by new weapons systems, rather than by political means,'' write MIT professors George Rathjens and Jack Ruina. First of six articles.