Something remarkable is happening in the science of life and...

Something remarkable is happening in the science of life and intelligence beyond Earth. The age of "technosignatures" is dawning. Credit: Getty Images / Pakin Songmor

On Dec. 18, the world learned that Breakthrough Listen, a privately funded search for extraterrestrial intelligence, had found its first official candidate signal. The signal's existence lit up the Internet. Was BLC-1, as it's called, finally our moment of contact? Breakthrough Listen scientists, now hard at work on a paper about their findings, were quick to explain that the answer was probably "no": Given the wealth of human-made radio signal interference out there, BLC-1 will probably turn out to be of human origin.

Their preliminary conclusion, however, does not defuse the excitement of BLC-1. The fact that there's a candidate at all is cause for celebration. That's because something remarkable is happening in the science of life and intelligence beyond Earth. The age of "technosignatures" is dawning.

Many people have the romantic notion that astronomers huddle over their telescopes every night and scan the skies looking for signals from distant, alien civilizations. That, unfortunately, just ain't happening. Though the Search for Extraterrestrial Intelligence (SETI) began more than 60 years ago, there was never sufficient funding or telescope time available to make a dent in the effort. In the 1980s and 1990s, some in Congress cited public SETI funding (as little as it was) as a press-worthy example of wasteful spending. Government support mostly dried up, leaving the field running on fumes. As Jason Wright and colleagues at Penn State have demonstrated, if the sky is an ocean that needs to be searched for life, so far astronomers have splashed around in just one hot-tub's worth of water. The reason we have not found life elsewhere in the universe is simple: We haven't really looked.

Now, however, the long desert of opportunity may finally be giving way to a new era of growth. In 2015, Internet billionaire Yuri Milner pledged $100 million to create Breakthrough Listen, a next-generation radio-based search for extraterrestrial intelligence. With a single stroke, Milner helped rejuvenate the field: The project provided access to telescopes from the Parkes radio dish in Australia and the Green Bank instrument in West Virginia, and provided resources to explore new search methods and technologies. These include machine-learning initiatives designed to accelerate "classic" SETI research of the kind epitomized by BLC-1. As pioneered by Frank Drake and others (and popularized by the 1997 movie "Contact"), classic SETI searches for signals that are anomalous, as opposed to those originating from natural or human causes. Historically, the challenge has been that SETI observations produce tidal waves of data. But artificial intelligence can enable computers to identify those all-important weirdness needles in the cosmic signal haystack of all that data.

Meanwhile, an entirely different kind of breakthrough — the exoplanet revolution — opened a second frontier in the search. For more than 2,500 years, astronomers had argued over the existence of planets orbiting other stars. Since life probably needs planets to form, answering this question was the critical first step in understanding if we were alone in the universe. Then, in the mid-1990s, astronomers found a Jupiter-size world on a four-day orbit around the star 51 Pegasi — and today, we know that almost every star in the sky hosts a family of worlds. Scientists worldwide are building a census of alien planets, showing which stars have planets and which planets are in the star's "Goldilocks zone," where surface temperatures are just right (that is, anywhere between freezing and boiling) for life to form. As a result, astronomers can find out exactly where they should be looking for life and intelligence.

Knowing where to look, however, is just the beginning. Astronomers are also gaining the capacity to probe the atmospheres of distant planets for biosignatures. (Alien astronomers looking at Earth, for example, would see oxygen and methane in our atmosphere — a signature of life's presence on our planet, since both chemicals would quickly react away without Earth's life breathing them back into the air.) By interrogating light passing through a far-flung world's gaseous veil, astronomers can compile its chemical inventory. They can see what's in the planet's atmosphere. Using existing telescopes, scientists have already explored the atmospheres of a few Jupiter-size exoplanets. The next generation of instruments, including the soon-to-be-launched James Webb Space Telescope, should enable them to explore the atmospheres of smaller, Earthlike planets and search for the chemical imprint of an exo-biosphere.

But why stop at biosignatures? The presence of technology on a planet might be as, or far more, detectable than that of just biology. The large-scale deployment of solar energy collectors by a civilization, for example, would leave an imprint on the planet's reflected light. Telescopes on the drawing boards right now might have the capacity to see city lights on distant worlds. All this means that the search for technosignatures is becoming just as plausible and just as important as the search for biosignatures, to which the astronomical community is already deeply committed. Technosignatures represent the thrilling new face of SETI, embracing both anomaly-based searches and targeted explorations of exoplanets and their environments.

NASA has been an essential part of this recognition: At the behest of Congress, the space agency convened its first meeting on what is now called "Technosignatures" Science in 2018. In 2019, my colleagues and I were awarded NASA's first-ever research grant to study atmospheric technosignatures, and this year, NASA funded two other technosignature studies. If the trend continues, the search for intelligence in the universe may finally escape the giggle-factor that for so long left it associated with bad sci-fi shows and generic UFO nuttiness. The field — which was pursued in the past almost exclusively by older, established scientists with less to lose — may finally establish a community of researchers at all levels of age and expertise.

That last step is crucial. While news of candidate signals like BLC-1 will always generate buzz, the truth about the search for intelligence — the search for exo-civilizations — is that it's probably going to take a lot of time and effort. That's the price you pay for great science; it's the price you pay to know something extraordinary. Getting used to that reality means paying as much attention to the journey as to the awaited results. That extraordinary journey — the one taking us to the shores of alien worlds — is really only just getting started.

Frank is an astrophysicist and the Helen F. and Fred H. Gowen Professor at the University of Rochester. He most recent book is "Light of the Stars: Alien Worlds and the Fate of the Earth". This piece was written for The Washington Post.


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