On Nov. 16, 1974, scientists fired off a nearly three-minute radio message into space with the express intention of communicating with intelligent extraterrestrial life. Broadcast from what was then the world’s largest radio telescope, in Arecibo, P. R., the message was delivered in the direction of M13, a globular cluster of stars about 25,000 light-years away. The M13 cluster was chosen in part because it includes hundreds of thousands of stars. Scientists hoped at least one may be orbited by a planet bearing intelligent life of some sort. The Arecibo message was a glorious demonstration of our species reaching outward into the universe for a connection to whoever was listening.
That’s precisely what the missive was — a demonstration of the Arecibo radio telescope’s technological prowess to fire off a powerful signal into the far reaches of space. It was never seriously expected to make contact with alien life. That should change. It’s time to follow up on that transmission 50 years later with a new, multigenerational project looking for proof that we are not alone in the universe.
We are living in strange and precarious times — marked by perpetual wars, a global climate crisis and polarized feelings about the state of the world. At this moment, when terrestrial concerns are tearing us apart, what if we looked to the heavens for a reason to hope? Knowing that another civilization is surviving the gantlet of its own challenges could reassure us. And while we hope to succeed in discovering and contacting other life, even concluding that we are alone in the universe could be a revelation that helps unite our species.
The Arecibo message tries to establish a common language with another species through math and science — subjects that should be universally understood by any extraterrestrial engineers who can build radio receivers. The message is made up of 1,679 radio pulses, which are meant to be organized into a two-dimensional graphic comprising 73 lines. Each line is 23 characters long. When decoded, the message begins by counting from 10 to one in binary. Then it lists key elements essential to life on Earth through their atomic numbers.
The message goes on to show the chemical formulas that combine these elements into the building blocks of DNA. The shape of the double helix (the molecular structure of DNA) is paired with the number of units that make up the human genome. Humans are described by their height and population on Earth. A stick figure hovers above a diagram of our solar system to point out our species lives on the third planet from the sun. To celebrate the technology that makes interstellar contact possible, the message ends with a diagram of the Arecibo radio telescope itself.
Should such a message ever reach another civilization and evoke a response, its impact would be world changing. Statistically speaking, any extraterrestrial species we contact will probably be much older — and hopefully wiser — than Homo sapiens. While humanity is relatively new to existential threats of its own making (like nuclear annihilation), any civilizations we hear from may have realized a stability and longevity inconceivable to us. Even if their reply is as simple as a confirmation that they got our message, the knowledge that it’s possible to survive the similarly monumental threats we face today will be profound.
But committing to the goal of making contact with intelligent alien life requires more than just one-off electronic letters fired randomly into space, like the Arecibo message. It needs to be a sustained endeavor, because interstellar messaging is woefully sluggish. The M13 cluster is far from an ideal target for establishing contact with another civilization. It takes 25,000 years for a radio message to traverse the 25,000 light-year distance. If we receive an immediate reply to our first message, it won’t be for about 50,000 years at the earliest.
Surely we can do better. We should start by targeting star systems closer to Earth, such as Proxima Centauri, located just a little over four light-years away and orbited by a potentially habitable planet. Transmitting toward star systems in our galactic backyard would dramatically reduce the time for a round-trip exchange. And the closer the star is to Earth, the “louder” our radio signal will be to aliens, making our message easier to hear. For example, if we send the Arecibo message to a star 25 light-years from Earth — a thousand times closer to Earth than M13 — it will be a million times easier to detect.
Why begin now? Because if we wait, we defer the possibility indefinitely. There are over 100 stars within 20 light-years of Earth. If a message had been transmitted to any of those stars some 50 ago, we might receive a response today. Within 50 light-years, there are about 1,800 stars. By one estimate, within 100 light-years, there are nearly 60,000 stars. Transmitting messages now could lead to first contact in just decades or centuries.
That doesn’t mean we’ll hear back immediately — or ever. From the moment we begin transmitting, to the centuries or millenniums we spend listening for a response, we may be met with only vast, cosmic silence.
But over time, we’ll come to realize that by committing to a project on a scale humanity has never undertaken before — and following through despite the uncertainty — we have become that long-lived, stable civilization we’ve been looking for all along.
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