How Little Lasers Might Light Our Way to Extraterrestrials
For 62 years, scientists have pointed instruments toward outer space in hopes of finding some sign that we’re not alone in the universe. But those instruments always scanned just a tiny swath of sky for a short span of time, limited mainly to listening for stray radio waves and leaving us largely blind to any visual evidence of extraterrestrials in the darkness of space.
Until now.
As the space age enters its seventh decade, the search for extraterrestrial intelligence (SETI) is getting a lot wider and more deliberate. And that could significantly boost our chances of actually finding something for the first time.
In mid-December, scientists with the SETI Institute in California finished installing a new laser instrument: an expensive lens-camera-computer combo at Haleakala Observatory, situated on a mountaintop on Maui, Hawaii, 10,000 feet above sea level.
The east-facing instrument, when combined with an identical west-facing system at the Robert Ferguson Observatory in Sonoma, California, scans a 150-degree arc of the night sky more than a thousand times a second, filtering the light and looking for the telltale signature of laser light—a possible sign of intelligent life. “We’re trying to cover all the sky all the time,” Eliot Gillum, the principal investigator for the LaserSETI project, told The Daily Beast.
Meeting that goal will require a few more instruments on the other side of the world, but the pair in Hawaii and California “is a big step toward full coverage,” Wade Roush, a science lecturer and author of Extraterrestrials, told The Daily Beast.
The expanding laser system complements older forms of SETI that listen for radio broadcasts or scan distant planets for visual evidence of current or extinct civilizations. Practitioners of the different modes of SETI—radio, optical and laser—are all trying to make their sensors scan more of the sky for longer spans of time.
Gillum and his team eventually want to look in all directions, 24 hours a day, using a bunch of different methods. “The SETI world has really shifted toward all-sky, all-the-time,” he said.
That persistence is critical, Dan Werthimer, a Berkeley astronomer, told The Daily Beast. “A typical astronomy research telescope looks at about one-millionth of the sky at a time,” Werthimer said. “So if E.T. is flashing us once a day, once a month, or once a year, we'd be very lucky to detect the flash with a telescope that can only examine a small part of the sky.”
Laser detectors are a key addition to the overall SETI effort. It helps that they are cheap as hell. The SETI Institute paid for the Hawaiian instrument with private donations and a measly $100,831 it raised from 531 backers on crowdfunding website Indiegogo. Gillum installed it himself with the help of a small team.
All things being equal, lasers aren’t necessarily the best way to spot E.T. “There are arguments to be made for a dozen different ideas,” Gillum said. An infrared telescope scouring the cosmos for artificial red light, for example, might be an even better addition to the SETI scientist’s toolkit, Gillum explained.
But infrared telescopes don’t work well on Earth’s surface, thanks to interference from the atmosphere. That means you have to put them in space. And that makes them really, really expensive. NASA’s new James Webb Space Telescope is an infrared instrument, and is sure to make a big dent in dozens or even hundreds of different scientific investigations. But it also took 25 years and $10 billion to build and launch Webb. NASA, let alone any other smaller space agency around the world, isn’t eager to burn through that much time and money to make another infrared space telescope any time soon.
So yes, lasers are low-hanging fruit in the search for alien civilizations. But that’s not to say they’re not ripe for plucking. In space, lasers are special. And that makes them pretty useful in SETI.
A laser is basically a single-color beam of light, like red or green. Besides being used to point at the white board in a giant lecture hall or keep cats entertained for a few hours, humanity uses lasers to communicate with satellites. It’s possible alien civilizations might also use lasers for comms of their own—or for other purposes, such as building a giant canon of lasers to push a spacecraft out into deep space at 20 percent the speed of light. (TBD on that idea.)
It’s even possible E.T. could flash lasers into space specifically in order to signal other civilizations like ours. “Such powerful lasers could be pretty easily seen by someone else’s… SETI experiment,” Seth Shostak, a scientist at the SETI Institute, told The Daily Beast.
Lasers work for SETI because they’re rare in outer space. It’s true that certain natural light sources can produce laser-like flashes under extreme conditions—the atmosphere of Mars, reflecting sunlight, can “lase,” for example. But natural lasers might pulse relatively slowly over a period of seconds. As we've seen with ones we've made on Earth, artificial lasers can flash quickly, like a sparkle lasting just a few milliseconds.
All that is to say, if Gillum’s new instruments detect a fast-flashing laser coming from space, it’s probably one of two things: some totally brand-new, previously unknown natural phenomenon … or aliens.
“Either way, exciting,” Gillum said. Say the new laser-detectors register the monochromatic flash of an artificial laser. The detection alone would be a profound accomplishment. “You should be booking a ticket to Stockholm to collect your [Nobel] Prize,” Shostak said.
But spotting a laser somewhere out there isn’t the same as making first contact with aliens. As time goes on and our technology improves, we’re detecting weirder and weirder stuff in our skies and beyond. Recent Mars missions, along with odd sightings of so-called "unidentified aerial phenomena" by U.S. Navy pilots, have helped drive a surge in interest in SETI.
That excitement is infectious, even in the scientific community. Sensing that some scientists are leaping to conclusions based on cursory discoveries (such as proteins on asteroids), NASA’s outgoing chief scientist James Green recently penned a paper urging his peers to place their data on possible alien life on a seven-step scale that ranges from interesting to definitive. “Our generation could realistically be the one to discover evidence of life beyond Earth,” Green wrote. “With this privileged potential comes responsibility.”
Detecting a laser might not rise very high on Green’s scale, at least not when there are possible (albeit very rare) natural sources of monochromatic light in space. After registering a flash of laser, scientists would need to confirm the observations through a slew of different instruments first. Only then would the real work begin to actually figure out whether the laser is being beamed by curious aliens or not.
And if we found out aliens are beaming lasers through space, what then? One suggestion is for scientists to signal back to E.T. by flashing our own laser. Depending on your perspective, you might be eager for humans to build a beacon like this and make contact with a distant civilization as soon as possible—or you might think it’s probably best if we keep our lights as dim as possible and don’t let the neighbors know we’re home.
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