That’s the thesis of a new book called Mixed Signals: Alien Communication Across the Iron Curtain, from science historian Rebecca Charbonneau.

Anybody who lived through even part of the Cold War knows what a strange time it was. The world was split into two, each side a stranger to the other, and the prospect of mutually assured destruction and the possibility that could happen tomorrow, was just a fact of life that we all had grown used to.

Thankfully, it didn’t come to that. Glasnost and perestroika, a stuttering Soviet economy and the fall of the Berlin Wall brought about a thawing of the frosty relations between East and West that led ultimately to an end to the Cold War. But the world was a very different place by the time the Soviet Union dissolved in 1991 compared to when the Cold War had begun in 1947. And because the Cold War defined that era, it’s influence in changing the world is undeniable, even in areas where one might not imagine it would be so pervasive. That includes SETI.

“It’s hard for me to imagine that SETI would look the way that it does without the Cold War,” says Charbonneau, who works at the American Institute of Physics. “Things like the ‘L’ factor in the Drake Equation, things like the Kardashev scale, they were just so of that particular moment that it’s hard to imagine that they would have existed in their exact form without the influence of the Cold War.”

One of the commonalities between the East and West during the Cold War was the militarisation of certain civilian activities. As much as scientists might like to pretend otherwise, astronomy and the military have always been bedfellows, and it hasn’t always been the military using astronomical technology for its own ends; sometimes astronomy has been able to take advantage of what the military has had to offer too.

Radio astronomy began back in the 1930s, when Karl Jansky noticed radio waves coming from the core of the Milky Way. Yet not long after, war intervened and any radio technology was subverted for military use, most notably in the development of radar. Yet even during wartime, radio astronomy continued to develop. Numerous army officers independently detected radio waves from the Sun, while mysterious, high-altitude radar echoes heard throughout the war were a puzzle.

To track these radar echoes down to their source, astronomer and former radar technician Bernard Lovell adopted army surplus radio equipment and set up a makeshift radio observatory at Jodrell Bank in Cheshire, near Manchester in the UK, shortly after the war ended. Again, the connection between the military and astronomy was evident. Lovell discovered that the mysterious radar echoes were from meteors burning up in Earth’s atmosphere.

Buoyed by his success, Lovell set about building the giant 76-metre Lovell radio telescope at Jodrell Bank, completed in 1957 but having run massively over-budget and with Lovell facing serious questions about his management of the project. Yet the Cold War came to his rescue.

The Cold War was waged not through direct conflict, but through both a series of proxy wars and through competing for prestige. Perhaps the most dramatic example of that was the Space Race, which the Soviet Union won in October 1957 with the launch of Sputnik 1, which orbited the Earth. Yet how to prove it? The Soviets wanted the world to see that they had sent a satellite into space, while the West, particularly the United States, wanted to track it – for all they knew it was a spy or weapons satellite. The Lovell telescope was the only radio telescope powerful enough to track Sputnik 1’s staged rocket, which was of vital interest to western governments because a rocket that could enter orbit could be used as an ICBM. Afterwards, Lovell received thanks from the United States, his own government and even the Soviet Union for shedding light on the reality of the dawn of the Space Age. For the next few years, the Lovell Telescope was an important part of Cold War shenanigans as it tracked each space launch, and Lovell himself was caught up in the paranoia of the time during an invitation to visit the Soviet Union that turned disquietingly sinister.

Over in the United States, radio astronomy took longer to catch on – somewhat ironic, given that it was an American, Karl Jansky, who kickstarted it all. Many astronomers in the United States were sceptical of the value of radio astronomy – they didn’t think there was anything interesting to be seen in the radio sky. The only extragalactic variable radio sources were known prior to the 1960s. This, of course, was before the discovery of thousands of radio galaxies, quasars and pulsars, and radio emission from regions of star-birth and star-death, interstellar chemistry, and much more besides.

The success of the Lovell Telescope in tracking Sputnik 1 convinced US spies that some form of radio monitoring technology was essential, and as this technology was pretty similar to the technology required by radio astronomy, the two developed synchronously. It was that technology that in 1960 allowed Frank Drake and his students, Margaret Hurley and Ellen Gunderman, to conduct the first ever radio SETI search, called Project Ozma.

They didn’t discover any alien signals, of course, but their search triggered a chain reaction that spread around the globe to the Soviet Union and gave birth to the SETI that we know today.

If the United States had Frank Drake and Carl Sagan, the Soviet Union had Iosif Shklovksii. Charbonneau describes Shklovskii as Drake and Sagan rolled into one.

“Project Ozma was a big catalyst for SETI in the Soviet Union,” Charbonneau says. Though news from the West was patchy and often late, a year after Project Ozma took place Shklovskii got wind of it, and it inspired him enough to write a book on the subject – Universe, Life, Intelligence – which acted as a call to arms for Soviet SETI.

“In some ways, SETI in the Soviet Union exists because of Iosif Shklovskii,” says Charbonneau. “He’s the one who supported his students like Nikolai Kardashev to be able to do their work. The way that science was conducted in the Soviet Union was that it was at the discretion of figures like Iosif Shklovskii, and it really boils down to his actions and his interests, and it does seem he largely got his interest because of the activity in the United States.”

Soon, Shklovskii became pen-pals of sorts with Carl Sagan, who had read Universe, Life, Intelligence and wanted to find an American publisher for it. With plentiful addendums added by Sagan, it was republished in the West as Intelligent Life in the Universe and, for many years, was the pre-eminent book on the subject. Sagan and Shklovskii’s contact across the Iron Curtain was part of a growing connection between SETI astronomers on both sides, all of whom tried to resist the efforts of national spy agencies to use the scientists for intelligence gathering.

The contact between Soviet and American SETI scientists was multi-layered. At face value it was a sharing of ideas. At a deeper level it showed that people of the East and West could work together as human beings. And deeper still, the difficulties that they faced in reaching out from their separate nations, quite alien to one another, and be understood was like role play for the day we really do make contact with an alien intelligence. This was not lost on the protagonists.

“They were very aware of the parallels between what they were trying to do, which was to make contact with ‘the other’, while very similarly trying to talk to each other – and they loved it,” says Charbonneau. “I went to the Library of Congress to read the letters of correspondence between Iosif Shklovksii and Carl Sagan. You could see it all throughout their letters and the way they talked to each other, almost as if they were extraterrestrial cosmonauts speaking to one another. Because at that time the United States and the Soviet Union were very alien civilisations to one another.”

American and Soviet SETI scientists even met up at a conference, co-organized by the US National Academy of Sciences and the USSR Academy of Sciences, at the Byurakan Observatory in Armenia in 1971. Yet even though the scientists were starting to get along, their governments were still at loggerheads and the spectre of mutually assured destruction loomed over everybody. And as it did so, it also worked its way into SETI.

Frank Drake’s famous equation is a calculation designed for making rough estimates regarding the possible number of communicating extraterrestrial species. It includes a variety of factors, from the rates of star and planet formation to the fraction of worlds that produce life. The very final term is ‘L’, the lifetime of a communicating species. L is such a large term, numerically, in comparison to the other factors of the Drake Equation that it is the dominant factor in the final estimate.

So L took on increased prominence, and immediately sparked discussions about the fates of civilisations, which inevitably led to meditations about the long-term survival of humanity. Drake devised his equation in 1961; a year later the Cuban Missile Crisis very nearly ignited World War Three. The discussion about the longevity of alien civilisations was mirroring our own fears of extinction.

“The way that SETI scientists spoke about L was not dispassionate,” says Charbonneau. “They were framing it in terms of these big questions, what are the fates of civilisations, do we inevitably destroy ourselves, and is technology ultimately the start of the demise of civilisation? The way that they spoke about it was so clearly tied to the Cold War anxieties that they were facing.”

Those anxieties have never really gone away, and today are trying to push their way back to the forefront, not just in the fear of nuclear war, but pandemics, climate change, artificial intelligence, descent into authoritarianism, and myriad other ways we can imagine dooming our global civilisation. L remains an uneasy legacy of the Cold War, a reminder that we can have a future, but that it could all too easily be snatched away from us. The continued silence from the stars is no comfort at all.

There’s one other way that the Cold War seems to have had influence on SETI, in that the only two nations that did SETI systematically were the opposing Cold War powers, namely the United States and the Soviet Union.

Charbonneau has been wracking her brain for answer. “In my book I’ve tried to figure out why it was really just the United States and the Soviet Union, and really nobody else. That’s weird, right?”

Charbonneau wonders if it is a by-product of the Space Race, itself motivated in large part by Cold War rivalries. And with that came an interest in all things space and science fiction. “I do think the rich tradition of science fiction in the two respective cultures is part of the answer, but it can’t be the whole answer, because other countries also had a rich science-fiction tradition and an interest in space.”

Perhaps it is less about cultures and politics, and more about people. Even in the United States and the Soviet Union, SETI was pretty niche and prone to ridicule, and still is, with relatively few people doing it. If it had not been for Frank Drake, modern-day SETI may never have got started. If it had not been for Iosif Shklovskii, Soviet thinking about SETI may never have happened. In contrast, in the UK – a nation with an interest in space research and a tradition of science fiction – the Director of the largest radio telescope in the world at that time, at Jodrell Bank, had no real interest in SETI. If he had, perhaps it would have been a different story. No, the beginning of SETI is a story of a handful of people in the right place, at the right time, able to harness the technologies and paranoias and anxieties and curiosities of the Cold War for good rather than for ill, and to cross political borders and lines on a map to reach out and communicate with each other, putting nationalism to one side to see the world, and other worlds, from a different perspective.

Maybe we’ll never find aliens, but SETI has allowed people to discover each other before, and perhaps it will do so again in the future.