The superpower weapons race heads into Earth orbit

From the launch of the first Russian Sputnik a quarter-century ago, which brought warnings of Soviet nuclear thunderbolts, space has been the 20th-century military frontier. For years now, the United States and the Soviet Union have had the ability to hurl hundreds of ballistic missiles, carrying thousands of nuclear warheads, through space.

But more recent developments in space may radically change the basis of nuclear deterrence, which is that both sides are mutually vulnerable and therefore unlikely to launch an attack in the first place. Whether this will be for better or worse undoubtedly will be the most controversial subject for discussion when superpower arms talks resume in Geneva next week.

Questions about the value of ``mutual assured destruction'' as well as technological advances are moving both superpowers in the same direction regarding space: looking for ways to attack each other's satellites (which would play a key role in launching and directing conventional as well as nuclear war), and lessening the vulnerability to nuclear attack by destroying missiles and warheads in midflight.

The Soviet Union has a system of interceptor missiles around Moscow, as allowed under the Anti-Ballistic Missile Treaty of 1972. The ABM agreement limits each side to 100 antimissile rockets at a single site.

But US intelligence and defense officials are concerned that the Soviets are preparing to ``break out'' of the ABM Treaty by expanding their missile defense system to cover much more of the nation. These officials point to the upgrading of the Moscow system, the construction of a large phased-array radar in Siberia, the testing of advanced antiaircraft systems against ballistic missiles, and considerable laser research.

US officials also repeatedly point out that the Soviet Union has the world's only operational antisatellite (ASAT) system. Mounted on large rockets, these devices orbit the earth several times, rendezvous with satellites, and explode. Some US officials also say the Soviets may have begun aiming lasers at US satellites in low-Earth orbit.

Even critics of the Reagan administration acknowledge that the Soviets may be stretching, if not violating, the ABM Treaty's restrictions.

But they play down the utility of the Soviet ASAT system. They note, for instance, that all of the tests of this ASAT in the more advanced infrared-homing mode have failed. And they say that the active radar device used on the earlier version of the Soviet ASAT could easily be ``spoofed'' with electronic countermeasures.

The knowledge that they are at least several years behind the US in the more advanced ASAT and antimissile technologies (especially sensors and information processing) is behind the Soviet call for a moratorium on ASAT testing and space-based missile defenses.

But the Reagan administration is very wary of any effort to stifle US efforts in this area. The President has made it clear that he wants to find a way of rendering nuclear warheads ``impotent and obsolete,'' and he has said that finding a way to verify an ASAT ban is extremely difficult, if not impossible.

The Pentagon has conducted three tests of its ASAT device, a miniature homing vehicle fired into space by a small rocket carried by an F-15 fighter. The first test against a target in space is scheduled for this spring. Experts say such a weapon could be much more effective than the relatively cumbersome Soviet ASAT and (because of its small size) deployable anywhere a tactical jet can take off and land.

For some years, the US has been spending about $1 billion a year on research related to missile defense. With his controversial ``star wars'' speech in March 1983, Mr. Reagan launched a five-year, $26 billion Strategic Defense Initiative that has since been accelerated. Officials stress that there is no plan to go beyond the ABM Treaty restraints -- at least for the next few years -- and that the SDI program is strictly a research effort.

Critics -- and there are many of them in the scientific and defense communities -- say the President's goal of eliminating the threat of nuclear war through space-based defenses is unattainable. And they warn that such an effort would simply spawn a new arms race, including the deployment of many more Soviet nuclear warheads to overwhelm strategic defense.

All of this could have significant impact on the coming arms talks.

Says former national-security adviser Brent Scowcroft: ``I think the Soviets are unlikely to be willing to contemplate significant changes in warhead numbers and [ballistic missile] throwweight if they have to look over their shoulder at some defense system that they may need to penetrate.'' -- 30 --{et