Introduction

How can we interpret signals from extraterrestrials when we struggle to interpret signals on Earth? We will begin not in space, but at the bottom of the ocean.

October 27, 1962 - the Soviet Foxtrot-class submarine B-59 cuts quietly through the depths of the Caribbean Ocean, armed with a nuclear-tipped torpedo. Above the surface, the Cuban Missile Crisis is reaching its height.

Suddenly, explosions. Left and right, the submarine is shaken by depth charges dropped by a US ship overhead. Concerned that they are under attack, and perhaps that nuclear war has broken out above the surface, the captain, Valentin Grigorievitch Savitsky, decides to fire the sub's nuclear torpedo. To do so, he must first have unanimous support from two other officers, the political officer and the deputy.

President Kennedy had earlier declared a blockade of sea traffic between Cuba and the United States. Robert McNamara, the US secretary of defense, sent to Moscow and Soviet submarines radio messages headed "Submarine Surfacing and Identification Procedures," which stated that the US Navy would take action to "induce [submarines] to surface and identify themselves" if found violating the blockade. The US Navy had orders - not to attack Soviets, but to drop warning charges to prompt submarines to surface.1

B-59 did not hear McNamara's message; it was too deep to receive radio communications.

The political officer, Ivan Semonovich Maslennikov, gave his authorization to fire. But the final officer, Deputy Vasili Arkhipov, refused to authorize. According to the ship's communications intelligence officer, Arkhipov did not see the charges, which had been dropped only to the sides of the submarine, as a hostile act of war.

This is not an attack, he argued. This is a signal.2

The history of the Cold War is in large part a history of signals: signals from the ocean, signals from the Earth, and signals from outer space. Unlike the two previous world wars - which were fought in trenches, boats, and airplanes, using toxic gases, guns, and bombs - many of the most significant features of the Cold War were battled through adherence to a set of signaling and listening practices and variations on them, including intelligence-gathering masked as diplomacy, satellites peeping from overhead, and scientific progress disguising threats of destruction. Fundamentally, signaling is a form of communication, and communication was the battlefield of the Cold War. The above episode also demonstrates that communication is rarely straightforward, especially between cultures that are foreign - or alien - to each other. Cold War communication often relied on signals and codes, and therefore was rife with the potential for miscommunication. After all, were it not for Deputy Arkhipov'sa understanding that the US charges were attempting to communicate a desire that the Soviets come to the surface and not a hostile act of war, the Soviets might have somewhat reasonably decided to retaliate with their nuclear arsenal, potentially igniting a "cold" war into a hot conflict that could lead to global annihilation.

In addition to signals, the history of the Cold War also concerns aliens. Cold War-era science fiction, spurred by the Space Race and by fears of an attack from above that were in turn prompted by the launch of Sputnik (and the beep-beep of the signal it transmitted) and by the rise of atomic weaponry, foretold alien invasions and first contact scenarios with a combination of delight and terror. Like the entire Cold War, these science fiction stories of extraterrestrials fundamentally concerned communication with foreign cultures - the act of sending, listening to, and interpreting signals. Take for example Gene Roddenberry's television show Star Trek, which first aired in 1966. Star Trek is set in the twenty-third century on the starship Enterprise, a military-scientific vessel operated under the auspices of the United Federation of Planets and tasked with both "exploring strange new worlds" from a scientific-technical perspective and maintaining peace throughout the galaxy through military power. Take away the rubber costumes and planet-hopping and Star Trek is simply a show about Cold War international relations and the scientific-military-industrial complex.3 As with the Cold War itself, much of the show concerned signals. Enterprise was constantly in communication with alien civilizations, picking up distress signals and being tasked with the difficult challenge of making first contact.

A spin-off from the original series, Star Trek: The Next Generation had an episode focused entirely on the challenges of communicating with the alien. The episode "Darmok" began with the captain of the Enterprise, Jean-Luc Picard, becoming marooned on an alien planet inhabited by a species whose members could communicate only in metaphors drawn from their own complex mythology.4 The entire 40-minute episode is dedicated to Picard's frustrations as he tried to conduct meaningful communication with a people whose culture and way of signaling differed significantly from his own. The act of communication with the "other" is a major theme of Cold War and post-Cold War science fiction precisely because it parallels the attempts of communicating with the "alien" on our own planet - those nations and peoples whose languages, cultures, and ontologies differ drastically from the familiar ones.

There was also an underlying sense of anxiety during the Cold War, similarly evoked in alien science fiction. Film theorist Susan Sontag, in an essay on science fiction evocatively titled "The Imagination of Disaster," famously wrote:

Here is a historically specifiable twist which intensifies the anxiety. I mean, the trauma suffered by everyone in the middle of the 20th century when it became clear that, from now on to the end of human history, every person would spend his individual life under the threat not only of individual death, which is certain, but of something almost insupportable psychologically - collective incineration and extinction which could come at any time, virtually without warning.5

But why was science fiction so prominent a genre in the United States and in the Soviet Union during the Cold War period? The rise of science fiction can likely be explained by the apotheosis of science in the postwar period. The Cold War's scientific-technical competition, arms race, and Space Race elevated the status of science and technology in both countries. Furthermore, one of the primary battlefields of the Cold War was outer space - not only in the Space Race, but in the less public race for gathering intelligence with the help of satellites and techniques of signals intelligence. As seen in Star Trek, aliens were a convenient stand-in for foreign civilizations with which we struggled to communicate and build some understanding. Considering this combination of science adulation, xenophobia, and newfound public awareness of outer space, it is no wonder that science fiction became a primary medium through which to express Cold War anxiety and aliens became its mode of expression. The subject of this book is not science fiction, yet I begin with this brief analysis to highlight the interconnected nature of science, warfare, anxiety, and aliens in the Cold War mindset. Recognizing these connections, let us turn our focus on the development of two sciences that arose in the early Cold War period: radio astronomy; and communication with (and search for) extraterrestrial intelligence.

A Cold War Science

Radio astronomy is a subdiscipline of astronomy that observes the universe in the radio part of the electromagnetic spectrum. Instead of the mirrors and lenses that optical telescopes use to observe the "visible" part of the spectrum (meaning those wavelengths of light that human eyes can perceive), radio telescopes use receivers, parabolic dishes, feed horns, and antennas to explore the "invisible" universe (meaning light in the cosmos that has a wavelength too long for the human eye to detect). Despite what you might have seen in Netflix's Three Body Problem and in other science fiction shows, radio astronomers do not use headphones to "listen" to radio signals; radio waves are not sound waves, they are light that our eyes can't detect. Radio astronomers use creative ways to visualize radio waves, often in the form of spectra and data-processing techniques that convert raw radio wave data into meaningful images and maps.

The rise of radio astronomy as a scientific discipline was not simply a revolution in astronomy but also a significant diplomatic development in the Cold War - integral to the facilitation of international scientific collaboration and citizen diplomacy during an otherwise geopolitically contentious period. Not only was radio astronomy an intrinsic part of mid twentieth-century scientific research in both the United States and the Soviet Union, but it helped promote a philosophy of scientific internationalism and facilitated successful scientific exchanges between nations locked in conflict. The reasons for these successes are twofold.

First, Cold War-era radio astronomers developed scientific techniques and experiments that sometimes necessitated global cooperation, incentivizing scientists in the United States and Soviet...