Zeus on Kwajalein

Lonely little Kwajalein Island, a 600-acre islet in the central Pacific, has known more than its share of excitement. World War II bombing raids left it almost bare of vegetation. In 1954 it was the first refuge of 82 inhabitants of nearby Rongelap, who were evacuated, their hair falling out in patches, after an H-bomb test had sprinkled their home with radioactive residue. When the radioactivity on Rongelap died down, the refugees returned and Kwajalein quieted down. But last week it was busier than ever as a task force prepared to test the Nike Zeus, the U.S. Army's anti-missile missile. On the glaring, sun-baked coral of Kwajalein, scientists hope to find an answer to an ominous question: Can a reliable defense be built against surprise attack by intercontinental missiles?

To Prevent Frying. The army is spending $75 million on Kwajalein, and the island already looks like the set for a science-fiction movie. Close to the coral beach, a circular, steel-mesh fence, 65 ft. high and 680 ft. in diameter, surrounds a rotating, triangular radar antenna, 80 ft. on a side. This electronic monster is named ZAR (Zeus Acquisition Radar), and when it sends its pulses into space to probe for incoming missiles, the fence will act as a shield to keep the powerful radio waves from frying all Kwajalein. Crewmen operating ZAR will go to work through a metal-shielded tunnel.

When a missile plunges into ZAR's range, it will reflect radar pulses back to Kwajalein. Waiting to detect them is a 1,400 ton Luneberg lens, an assembly of foamed plastic cubes containing metal threads, which will concentrate the reflected radar energy like a magnifying glass. The lens rotates in time with ZAR on a massive thrust bearing, and is housed in a plastic sphere 100 ft. in diameter.

ZAR's job is to detect an incoming missile while it is still high in space. As soon as the missile has been "acquired," another radar (Zeus Discrimination Radar) will zero in and decide whether the approaching object is actually an enemy warhead, or a decoy, or a bit of space flotsam. If it is a warhead, the missile will be turned over to a third radar, which will track it until the time comes to shoot it down with a three-stage Nike Zeus rocket. All this will be automatic, and it will happen too quickly for human hand or brain to follow. To complicate the procedure still further, the Army's scientists expect the various radars to raise such an electronic racket that stand ard communication signals from Kwajalein will be drowned out. Radio messages for the outside world will first pass through a submarine cable, then be put on the air at comparatively quiet Gugeegue island.

Moment of Truth. The intricate Nike Zeus base on Kwajalein is now close to completion. Its effectiveness against long-range missiles will soon be tested with electronic tapes--flight recordings of rockets fired from Cape Canaveral down the South Atlantic range. Played over and over again, the tapes will provide plenty of practice in "intercepting" intercontinental missiles. Then there will be tests against comparatively small rockets lobbed toward Kwajalein from Roi-Namur island about 50 miles away.

Some time in 1962 will come the moment of truth: a real Atlas will be fired toward Kwajalein from Vandenberg Air Force Base in California. If all goes according to plan, the speeding speck in space will be detected many hundred miles away, and its course will be calculated. A Nike Zeus rocket will rise from the island to meet the Atlas far above the atmosphere. Neither the invading nor the defending rocket will carry genuine nuclear warheads (no one on Kwajalein wants a dose of peacetime fallout), but the Nike Zeus will be credited with a theoretical kill if it comes within lethal distance of the invader.

Skeptics abound who doubt that the Nike Zeus system will work well enough to justify its cost (nearly $900 million). They point out that a station can be saturated by coveys of attacking missiles arriving at the same instant. A simpler enemy stunt, the critics say, would be to make a single missile spew out electronic decoys that would look like warheads to the discrimination radar. Then most of the defending rockets that roared into space would waste their nuclear thunder.

But even if the first tests do not succeed, they may well be needed to point the way to more advanced systems of missile defense. The byproducts of the Nike Zeus program may be valuable too. One example: the solid-propellant boosters that toss the big rockets into action can already generate 450,000 lbs. of thrust, beating by a wide margin the 389,000-lb.-thrust Atlases, on which the U.S. now depends for its push into space.

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