Science: Veil Around the World

It almost seemed impudence. Man, in cosmological terms an all but invisible presence on the surface of the earth, had flung aloft an apparatus which disturbed the order of the heavens themselves, made auroras flare in the skies, a hemisphere apart. Exploding nuclear bombs 300 miles above the South Atlantic, the men of Project Argus spun a veil of electrons around the earth, boldly using the atmosphere and nearby space as their laboratory.

Arching Lines. Project Argus began with a suggestion from Nicholas Constantine Christofilos, 42, a remarkable engineer-scientist of limited academic training but highly original ideas. For centuries, scientists have known that the earth behaves as if it had a great bar magnet inside it; lines of magnetic force make compass needles point to the magnetic north and south poles. As magnetic theory developed, scientists realized that the lines of force must arch high above the atmosphere. More than 50 years ago they began to speculate on how charged particles such as electrons would behave in the vacuum of space near the earth.

Late in 1957 Christofilos (see below) became convinced that high-speed electrons released above the earth’s atmosphere would be trapped by the magnetic field and circulate in complicated paths for a considerable time. When Dr. James A. Van Allen discovered shortly afterward by means of the Army’s Explorer satellites that such a radiation belt actually existed and conformed to the predicted magnetic contours, the Christofilos suggestion looked even more reasonable. But no one knew whether man could produce enough electrons to affect the whole earth or whether they would prove, in the words of one scientist, “a teaspoonful in a sea of natural radiation.”

Racing Particles. Since a good source of electrons is atom bombs, which give off vast swarms of them, military authorities realized quickly that rocket-borne atom bombs, exploded at the proper altitude over the proper part of the earth, would test peaceful magnetic theories while giving answers to military problems. e.g., the possible use of atomic charges exploded above the atmosphere as a defense against ballistic missiles. When an atom bomb explodes in the atmosphere, its fireball stops expanding when its pressure falls to that of the air around it; in the vacuum above the atmosphere, the fireball expands indefinitely. Ahead of its hot, ballooning shell races a host of electrons, other particles and gamma rays that would be stopped soon by the lower-lying atmosphere. Thus its lethal above-the-atmosphere range should be vastly increased.

Late last August and early in September, three small (1.5-kiloton) nuclear charges were fired into space by rockets from the Navy’s missile ship Norton Sound near the Falkland Islands in the South Atlantic. The Argus shots worked like a charm. Electrons released 300 miles above a point in the South Atlantic were captured, just as theory predicted, by the arching lines of the earth’s magnetic field. Some of them went south, cutting into the top of the atmosphere not far from the Norton Sound and causing the glow of an artificial aurora. Others went north, soaring high into space in tight spirals and slamming down to hit the atmosphere and cause a second aurora at the corresponding point on the far side of the magnetic equator (see diagram). Obviously Argus’ electrons amounted to more than a teaspoonful.

Doughnut Shell. The path followed by the electrons depends in part on their speed. To be trapped by the magnetic field, they must have more than 1 Mev (million electron volts) of energy, which means that they move almost at the speed of light. When passing above the magnetic equator, their spirals open out until their paths are almost straight along the magnetic lines of force. As the particles move down toward one of the magnetic poles, their spirals get tighter. Near the top of the atmosphere, they reverse and start another arching spiral toward the other magnetic pole. According to unofficial Pentagon information, the electrons from Project Argus made the trip from southern to northern hemisphere in a small fraction of a second.

Some of the electrons died when they hit atoms in the atmosphere and caused the auroral glow. Others made the round trip many times, but they did not follow exactly the same path each time. Spiraling back and forth, they gradually shifted around the earth, forming in about one hour a great shell like a doughnut. How long the shell lasted has not been told.

Presumably it died away in a few days as its electrons got mired in the atmosphere. But according to some accounts, the Argus shell was stronger for a short time than even the Van Allen natural radiation.

High-altitude nuclear explosions set off over Johnston Island southwest of Hawaii in early August had more limited objectives. Electrons from them caused an artificial aurora across the magnetic equator that was reported by New Zealand scientists in Samoa. But they were too low (about 100 miles altitude) to inject their electrons into a real vacuum. And so their effects did not spread around the whole earth.

Results & Complaints. The strictly military lessons of Project Argus will presumably be kept secret, but they may have already affected U.S. planning for above-the-atmosphere warfare. Dr. Van Allen has stated that neutrons from a nuclear charge exploding in a vacuum might detonate or inactivate an incoming enemy warhead, “if there were enough of them.” Other authorities declare that “enough of them” is an improbably large figure, and that it would be easy to protect the warheads with a shield of some neutron-absorbing material like boron 10. Such controversies will not be settled for the general public for a long time.

Even less clear is Argus’ effect on radar and radio. The Johnston Island explosions knocked out radio communications for 700 miles, but they were in the high atmosphere, not in space, and were much more powerful than the South Atlantic charges. Presumably, Argus had some global effect, since the Russians seem to have noticed that something was going on. Some scientists suspect that there may never be a full report. The effects in space were monitored by Explorer IV satellite orbiting overhead and by rockets shot up from the U.S. and elsewhere. But the Department of Defense, overconcerned with security, failed to tell more than a handful of electronics experts to watch for radio effects. Scientists are also impatient about the delay in publishing the data of the experiment. Six months, they think, should have been long enough for abundant study. They can hardly wait to see the results firsthand.