The Electronic Arsenal

Military electronics came of age in 1940 when British defense forces used bulky, primitive radars to spot fleets of approaching Luftwaffe bombers in time for R.A.F. interceptors to knock them out of the sky. Ever since, scientists have been busily expanding the world's electronic arsenals--while colleagues have been just as busy devising electronic countermeasures. The ingenuity and success of both efforts have been demonstrated in the skies and battlefields of Southeast Asia and the Middle East. The time-tested tactical adage that urges field commanders to "take the high ground" has now been all but replaced by a new military imperative: "To win, an army must gain electronic superiority on the battlefield."

Making use of everything from steadily shrinking microcircuitry to high-speed computers and high-energy laser beams, the three U.S. military services this fiscal year are pouring at least $500 million into research and development of new electronic snooping and jamming gear. That bill reflects not a penny of the price paid for R. and D. in the electronics of some new offensive weapons so costly that the military can barely afford to test-fire* them.

To keep pace with the Soviets, who have been working overtime on their own sophisticated electronics weaponry, the Pentagon's spending for electronic warfare will rise by at least 30% this year, one of the largest individual hikes in the military budget. Some of the more remarkable areas of research and development:

ELECTRONIC COUNTERMEASURES (ECM): Although the electronic "bubbles" that surrounded U.S. bombers and fighter-bombers over North Viet Nam gave them a high degree of protection against missiles and antiaircraft fire, the Soviets may learn to pierce the bubbles. The U.S. answer: new ECM techniques that can fool enemy radar into "seeing" a plane in the sky some distance away from where it actually is. Still largely cloaked in secrecy, the technology depends on mimicry and deception. Once a plane's instruments sense that radar signals are bouncing off it, they identify the type of pulses, memorize them and then retransmit them. But the apparent radar echo is sent back with a different interval between pulses, or with the pulse altered--or both. Ground-based radars that decipher the new signal are likely to locate their target in the wrong part of the sky. As one electronics expert told Aviation Week, the phony echoes can give a radar "a bad case of schizophrenia."

ANTI-SURFACE-TO-AIR MEASURES:

The U.S. had no answer to the Soviet-built SAM6 missiles that savaged Israel's American-built Phantom and Skyhawk jets during the 1973 Middle East war. Fired in clusters, the missiles have infrared, heat-seeking systems that guide them directly to the hot exhaust of a jet engine. They can also be guided by ground-based radar or their own onboard radar that can independently seek out an enemy plane. The frequencies of the radar signals can be so rapidly changed that electronic countermeasures become extremely difficult. Only after examining SAM6 missiles captured by the Israelis did the U.S. learn how to equip jets with electronic countermeasures capable of foiling the versatile missile. U.S. scientists are also developing a new missile called HARM (high-speed anti-radar missile), which will have its own computers to enable it to ride the radar beams of the SAM-6's ground-based control and home in on the launch sites. Slated to replace the Shrike and Standard Arm missiles, which knocked out SAM-2 missile sites around Hanoi, HARM has a range often miles.

COUNTER-COUNTERMEASURES: The Russians have not stood idly by while the U.S. was developing techniques to fool their missiles and radar. A Soviet text on electronic warfare translated by the U.S. Air Force describes several methods for helping ground radar to deal with bogus echoes from an ECM-equipped plane. One method is to use several tracking antennas, each of which seeks different information about the aircraft. The U.S. Sixth Fleet in the

Mediterranean recently got another hint of Soviet skills. A Soviet destroyer came so close to a U.S. ship that the sailors on deck could see it clearly; yet the electronic fog thrown up by the Russian destroyer was so dense that the American radar was blinded.

AUTOMATED SENTINELS: Some of the most effective snooping--electronic intelligence gathering (ELINT)--is done quietly without human intervention. On the sea floor, the U.S. Navy has a widely dispersed network of unmanned detectors that have "ears" so sharp they can pick up the hum of a passing submarine's props--or the thrashing of a whale--and pinpoint its location. Circling the earth, the Air Force's "Big Bird" satellite constantly scans the surface below with radar, cameras and electronic sensors that are so effective they were able to follow the movement of individual tanks across the Sinai desert during the 1973 war. Farther off in space, the Air Force operates a battery of watchdog Vela satellites that carry so wide a variety of sensitive detectors --infra-red, Xray, gamma-ray, cosmic-ray--that they can pick up the reverberations of a nuclear test anywhere on earth or moon.

COMMAND POST IN THE SKY: Defense Secretary James Schlesinger this month urged Congress to approve the construction of a squadron of modified Boeing 707s equipped with monstrous, mushroom-shaped radar domes for the Air Force's new airborne warning and control system (AWACS). Literally a command post in the sky, each plane will cost $111 million--the most expensive plane ever built by the Air Force. Packed with computers, radars and jamming gear, the AW ACS will be able to spot far-off targets, including very low-flying planes, and feed instructions to wide-ranging U.S. combat aircraft. Over the English Channel recently, a prototype plane was able to direct an entire simulated NATO battlefront, even while it was keeping an eye on aerial movements in East European and Russian airspace as far away as Moscow.

LASER-GUIDED ARTILLERY: The Army is enthusiastic about the potential of a newly developed 155-mm. shell. Fired from a conventional cannon, the 6-in. shell sprouts tail fins and small forward wings to prevent spinning. It can be aimed up to 500 yds. wide of a target illuminated with a laser beam projected by a forward observer. A "seeker" in the nose of the shell picks up the laser reflection, controls the fins and thus guides the shell to the target. Another application of the laser is giving tank guns more accurate range finders. Once they get a target in their sights, tank gunners merely press the laser button, hitting the enemy with the beam. An on-board computer then gauges the reflected light, makes nine separate calculations and fires the gun. In tests, the system has provided up to 40% more first-round hits than conventional equipment.

CRUISE MISSILES: Confronted by the growing number of so-called cruise missiles aboard Soviet ships and planes, the U.S. Navy is taking a new look at such surface-to-surface weapons. Descendants of the Nazi V-l "buzz bombs" of World War II, cruise missiles are similar to unmanned planes. Equipped with turbine engines and stubby wings, they can be launched from ships, aircraft or even submerged submarines; a rocket booster propels the missile until it breaks through the water's surface and its engine takes over. When equipped with a terrain-following electronic guidance system, which is now being developed, it should be able to skim great distances over land or water (as far as 1,500 miles). while eluding enemy radar defenses. (In contrast, ballistic missiles follow high, arcing trajectories, which make them more vulnerable to radar detection.) Because the recent Vladivostok arms-limitation accord does not specifically limit cruise missiles, some strategists are even beginning to think of them as first-strike weapons against Soviet missile silos or military bases.

MIRV AND MARV: No greater challenge faces the architects of electronic warfare than to devise a defense against MIRV (for multiple independently targeted re-entry vehicles) nuclear missiles, which scatter warheads toward several different targets after the rocket re-enters the atmosphere. The more deadly MARVs (for maneuvering reentry vehicles) have several separate nuclear payloads that can be maneuvered in different directions and at varying speeds as they plunge toward earth --making them even more difficult to intercept. The U.S. has already MIRVed a good number of its missiles and hopes eventually to MARV others. To help meet the threat of Soviet MIR vs now being deployed, the Pentagon has ordered major "rewiring" of both the pyramid-shaped nerve center of the Safeguard anti-missile system in North Dakota and the North American Air Defense Command's Cheyenne Mountain headquarters in Colorado, which keeps track of every man-made object in space (3,269 at last count).

Even the most optimistic American strategists are frank to admit that no new weapon--or defense against an adversary's new weapon--will stand unchallenged for long. Every new achievement spurs ambitious and expensive counterefforts. As a result, the life span of each new kind of weaponry becomes shorter and shorter; even the "smartest" electronic devices may be obsolescent soon after they reach the battlefield.

* For example, each U.S. infantry team being trained to use the TOW, a wire-guided antitank missile, is allowed to fire only four of the 3,200 missiles a year.

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