How the World Learned About the Pentagon’s Sky-High Nuclear Testing

In 1958, the U.S. military detonated atomic weapons high in Earth’s atmosphere—and found itself in a battle with scientists and the press to control just how the world found out.

A black-and-white photo of antinuclear protesters holding signs in Cape Canaveral, Florida
Antinuclear protesters in Cape Canaveral, Florida, in 1958 (Anonymous / AP)

Sometime in the summer of 1958, Hanson Baldwin, a longtime military correspondent for The New York Times, uncovered the Pentagon’s latest, biggest secret. Dubbed Operation Argus, it was the brainchild of the eccentric Greek-American physicist Nicholas Christofilos, a response to the fears of a possible Soviet missile attack that gripped the United States in the wake of Sputnik the previous autumn. Argus would detonate atomic weapons in outer space, creating an artificial radiation belt in Earth’s magnetic field that would supposedly fry incoming Soviet warheads in flight. Already, in utmost secrecy, an enormous naval task force was assembling in the remotest spot on the planet, the frigid South Atlantic, to launch nuclear missiles from the rolling deck of a ship in a crazily ambitious Cold War gamble.

A key player in Argus was America’s latest satellite, Explorer 4. It launched in July 1958 ostensibly as part of the International Geophysical Year (IGY), in which 67 nations came together to explore and study the planet that they all shared, in a spirit of complete scientific openness and collegiality. But as its builder, the physicist James Van Allen, knew quite well, Explorer 4’s true purpose would be to study the effects of Argus. He was no stranger to the peculiar world of official secrecy; for years, much of his research, including the recent discovery of the Earth-girdling radiation belts that now bear his name, had been conducted and supported using military resources.

This post is adapted from Wolverton’s new book.

Van Allen didn’t realize that Baldwin’s information had apparently leaked from his own lab at the State University of Iowa. Possibly a graduate student, possibly a technician—the identity of Argus’s own whistle-blower has never been definitively ascertained, even after six decades.

Baldwin knew he had a big story, but as a Pulitzer Prize–winning war correspondent, graduate of the U.S. Naval Academy, and savvy observer of all things military, he knew the serious ramifications of revealing such a secret operation, especially before it even happened. He decided he needed some guidance on the scientific aspects of it all, so he confided in his Times colleague, the science reporter Walter Sullivan.

“About the end of June, 1958, [Baldwin] put his head in my office and asked if he could talk to me privately for a few minutes,” Sullivan later wrote in his book-length account of the IGY, Assault on the Unknown. “He had learned, he said, that the United States planned to fire several atomic bombs in space.” Baldwin explained his reluctance about going public too soon. In the meantime, Sullivan suggested consulting a friend of his who was “so centrally involved in the U.S. space program that he would be sure to know of the operation.” That was Richard Porter, chairman of the IGY Panel on Rockets and Satellites. Sullivan was sure that Porter would also “give us his candid personal opinion, rather than merely an official line.”

Porter was “both horrified and amused” when Sullivan told him what he and Baldwin had already uncovered. “I can’t tell you not to print it, but I can say this: If you do, the operation will never take place,” he told the science reporter. To emphasize the point, about an hour later Sullivan got a call from the Pentagon’s Advanced Research Projects Agency (ARPA), imploring him to hold the story. ARPA assured Sullivan that Argus would be officially announced and revealed to the world after it was all over, and that the Times would be informed in advance so it could be the first to break the story. Realizing that they’d obviously struck a very sensitive nerve somewhere within the bowels of the Pentagon, Sullivan and Baldwin agreed to sit on the story until the operation had actually taken place.

By the end of 1958, Operation Argus was long over, the task force disbanded, and the faint, militarily ineffectual orbital radiation belts it had generated now faded from existence. And the dark curtain of secrecy and security cloaking Argus was also beginning to falter, as Baldwin and Sullivan began to feel their exclusive scoop slipping away.

In October 1958, Nicholas Christofilos presented his idea of creating an artificial radiation belt at the Chicago meeting of the American Physical Society. “The only major point he omitted was the use of an atomic bomb,” Sullivan later complained. Then came the annual meeting of the American Association for the Advancement of Science (AAAS) in Washington, D.C., just after Christmas, which Sullivan duly attended as part of his usual Times science beat. At the meeting came more rumblings of Argus from other quarters, including a paper on “Artificial Modification of the Earth’s Radiation Belt,” which inspired questions from a Newsweek reporter about possible connections with high-altitude nuclear explosions. Sullivan realized that his Newsweek colleague was really asking about Argus, albeit indirectly and perhaps somewhat shooting in the dark.

Old pros that they were, Sullivan and Baldwin knew that journalistically speaking, if other reporters had caught the scent, then the game was almost up. They decided to take more decisive action in order to guarantee an exclusive for the Times. Sullivan wrote to the Pentagon’s scientific director, Herbert York. He mentioned some, but not all, of what he knew of Argus, and requested a meeting to discuss going public, emphasizing that the Times didn’t believe it could continue to hold the secret indefinitely.

That was enough to set off some alarms at the White House and Pentagon. York consulted with James Killian, the chairman of the President’s Science Advisory Committee (PSAC), noting, “I know that he [Sullivan] knows considerably more than he has written.” He also pointed out that scientists such as Van Allen were increasingly pressing for the publication of Argus scientific data, as required by IGY agreements.

To help prove his point that Argus could be uncovered with a little “concentrated effort,” Sullivan checked with the IGY monitoring networks and casually inquired whether there had been any indications of unusual magnetic storms around the end of August and the beginning of September. He was informed that yes, there had in fact been a “rather remarkable event” around that time that couldn’t be associated with any definite solar disturbance of the sort that generally created such phenomena. Sullivan also checked around with other official sources, including overseas, for reports of unusual magnetic or auroral activity around that same time period. He detailed his poking around in another letter to York.

In a meeting with York at the Pentagon, Sullivan laid out the case for going public. “They had studied my letters and apparently had discussed them with James Killian,” said Sullivan. But they thought that the evidence Sullivan and Baldwin had collected was “inconclusive.” Sullivan argued that since knowledge of the radiation belts and ideas for Argus-type experiments were already quite public, any disclosure of the Argus shots wouldn’t tell the Russians anything they didn’t already know. York agreed in a general sense, but pointed out that information on the explosions, such as their altitude, yield, and geographic location, was indeed sensitive and had to be concealed for national-security reasons, and again officially asked the Times to hold the story.

Sullivan was far from satisfied by the entire encounter, smelling political maneuvering. “I am convinced that the only reason we are being discouraged by the Pentagon … is to postpone the day of diplomatic reckoning,” he told Baldwin. Specifically, he thought that with nuclear-test-ban negotiations then ongoing in Geneva, the last thing the government wanted was to reveal that the United States had been secretly blowing up atomic bombs in space. Scientists involved with Argus had been telling Sullivan the same thing.

There was indeed a rapidly growing rift between the scientists pushing for declassification and openness on one hand, and the Pentagon striving to maintain secrecy on the other. A memo to Killian on January 14, the same day as York’s meeting with Sullivan, noted that “it is to be expected that fragmentary unauthorized releases and leaks will occur,” and that “enough have already occurred to have attracted the curiosity of many scientists.” Declassification “would have beneficial effects on our own scientific community since it would equip them with working knowledge and would stimulate them to develop new ideas and inventions based upon the newly demonstrated effects.”

Aside from coalescing around military and scientific poles, the intramural debate began to settle down into two broad options, which were set out by Presidential Special Assistant Karl G. Harr in a memo to Killian on January 20. “There appear to be two contingencies: first, the publishing of information about the shots as a result of leaks and, second, the voluntary release of information by the Government … If The New York Times, or anyone else, breaks a substantial part of the story, our alternatives appear to be: 1. Neither to confirm nor to deny such leaks; 2. To disclose all that we may safely do from a national security point of view.” Harr pointed out that waiting for the story to break on its own would mean that “we would have lost control over the manner and timing of such release.” He proceeded to recommend, among other things, that “appropriate scientists prepare a report” and that Congress and the appropriate foreign powers, including the Soviets, be officially informed as well. He even provided a handy set of guidelines to govern such a public release, including emphasizing that “the detonations produced no radioactive fallout”; that “there was no violation of our IGY commitments” because unclassified satellite data had been released; and that “this was not the test of a weapon in the usual sense, but a scientific experiment.”

Sullivan and Baldwin as yet knew nothing of all the consternation they had caused within the hallowed halls of the White House and the Pentagon. As far as they were concerned, in the previous summer they had made a gentleman’s agreement to keep the secret of Argus until it was all over and made public, and now their reasonable expectations to at last publish the story were being summarily dismissed and endlessly delayed. The time had come for a direct approach, closer to the top. On February 2, James Killian happened to be in New York to make a speech. Sullivan figured that was his chance.

After Killian finished his speech, Sullivan approached him with a handwritten letter. He handed the sealed letter to Killian personally, making sure it wasn’t going to be intercepted and round-filed by some trusty assistant running interference for his boss. As the banquet hall emptied, Killian and Sullivan took seats. Killian opened and read the letter as Sullivan waited.

The letter patiently spelled out The Times’ position. “We were given repeated assurances that we would be given sufficient prior notice of any announcement so that we should be the first to publish it,” Sullivan had written. “To avoid inadvertent disclosure, knowledge of the project has been limited, on the Times, to Hanson Baldwin and myself.” Despite prior assurances, however, Sullivan noted that, apparently, “a policy decision was made some months ago not to make any disclosure about Argus.”

But that position, Sullivan argued, was no longer sustainable. He detailed the various reports on Argus effects that had come out in the scientific literature, not to mention “questions asked by science writers at the AAAS annual meeting” that “suggest that some of them are on the track of Argus.” Given all that, continued the letter, “we doubt that we can continue to withhold publication of at least a limited account of Argus.” Scientists they had consulted were unanimous that revealing Argus “would not disclose anything which was not already known, from the scientific and military point of view.” And Sullivan again pointed out the U.S. obligation to publish Explorer 4’s IGY data.

Killian didn’t argue with Sullivan’s reasoning, but sidestepped it by pointing out that disclosure of Argus could derail the Geneva test-ban negotiations. When Killian said that he also couldn’t provide any advance notice in case the government went public, Sullivan asked if at least someone could tip off the Times informally. “His reaction to this seemed to be assent, but we were still left in an uneasy situation.”

The scientists were getting restless as well. Later in February, a classified 10-day meeting on Argus results ended up in heated discussions over the question of Argus classification. Scientists concluded that it was perfectly possible to separate out the science from the military secrets.

It remained only for Killian’s PSAC to make its own judgment. At its monthly meeting on March 16, PSAC decided that “continued security classification … is not of significant military advantage to the U.S.” While PSAC had originally recommended that Argus be classified as top secret, “there are no longer any scientific or technical considerations which can justify the continued classification of the [Argus] tests.” PSAC also reiterated the argument that revealing Argus would enhance American prestige and thereby offset any political fallout that might result from inadvertent leaks. The upcoming meeting of the National Academy of Sciences in April would be the perfect venue to tell the world about Argus, PSAC thought.

All were fully aware that The New York Times was lurking in the wings, straining at the bit to publish the whole story but patiently awaiting some stamp of official approval. But it wasn’t going to wait forever, particularly when Hanson Baldwin got wind of the rapidly building momentum within the government and even the Pentagon to go public. After being so patient and conciliatory for almost a year now, it seemed that Baldwin, Sullivan, and The New York Times were about to be scooped by their own government. “We feared that, once the decision was made in Washington, the machinery might move so fast that we would be left hanging in the dust,” wrote Sullivan.

If that was the case, then it was pointless to sit on the story any longer. Baldwin and Sullivan went to the top: the New York Times publisher Arthur Hays Sulzberger, president Orvil E. Dryfoos, and managing editor Turner Catledge. After hearing the case laid out for them by their long-suffering reporters, the Times brain trust gave the go-ahead for publication—with the proviso that Sullivan and Baldwin notify the White House first as a courtesy. If the White House protested that publication would seriously harm national security, the Times would continue to hold off.

Around 4 p.m. on March 18, Sullivan tried to call Killian, but the science adviser was out of the office. Sullivan laid out the situation for Killian’s assistant. “He said that matters had proceeded too far to withhold publication of the story any longer,” the assistant wrote in a memo. “When I asked if this was an irrevocable decision, he said that it had certainly proceeded far enough to make such a change very difficult; that it was essentially irreversible.” Sullivan promised “to keep the yield, time, place, and height of the experiment in vague terms.”

Baldwin called ARPA and spoke to its director, Roy Johnson, basically giving him the same pitch: The Times was about to publish. The administration began to circle the wagons, deciding who would be responsible in which agency for answering what questions, and in general deciding on the officially approved story. Everyone settled in to await the coming onslaught.

Sullivan and Baldwin spent the rest of the evening scrambling to write the main Argus story along with supplemental material, and to prepare accompanying maps, photographs, and diagrams, all while waiting for a fateful call from the White House that could yet stop everything dead.

“Hanson and I watched the clock tick away the final minutes until the great presses in the basement began to thunder. They rolled. No call ever came. And the world learned of Argus.”

Much to the relief of Sullivan, Baldwin, and a great many scientists, including James Van Allen, the White House for whatever reasons had apparently decided to bow to the inevitability of the free press and the might of The New York Times. On the morning of March 19, 1959, one of the greatest secrets of the Cold War became one of its biggest public stories, spoiling President Dwight D. Eisenhower’s breakfast.

This post is adapted from Wolverton’s new book, Burning the Sky: Operation Argus and the Untold Story of the Cold War Nuclear Tests in Outer Space.