If you’re looking to communicate with distant aliens, laser power is your best friend. A new early-stage study proposes creating a beacon from Earth that could be seen as far as 20,000 light-years away — or about 5,000 times further than the nearest star system from Earth, Alpha Centauri. It’s a new way to tell extraterrestrials we’re here.
In theory, all the project would need is a 1- to 2-megawatt laser. Scientists would focus the beam through a 30- to 45-meter telescope and then point the thing at space. The result would be a huge channel of infrared radiation that would be strong enough to see from far away — even with our nearby sun hogging a lot of the infrared energy in the neighborhood.
This signal would be visible across many star systems, but it’s the potentially habitable ones nearby that astronomers are most interested in. Another possibility (besides the Alpha Centauri system) is TRAPPIST-1, a star only 40 light-years away that may be home to three habitable exoplanets.
“If we were to successfully close a handshake and start to communicate, we could flash a message, at a data rate of about a few hundred bits per second, which would get there in just a few years,” said James Clark, a graduate aeronautics and astronautics student at the Massachusetts Institute of Technology and lead author of the study.
Can We Build It?
Clark says it’s possible we could even make this signal with today’s technology — he describes it as “a challenging project, but not an impossible one.” At the least, it would generate a bit of an odd infrared signal that would mess up the signal our sun produces, which would attract some extra attention.
The U.S. Air Force once developed an airborne laser of 1 to 2 megawatts that was supposed to shoot down incoming ballistic missiles. And as for a 30-meter telescope, it’s something that will be feasible very soon. Two telescopes of similar size are already under construction: the 24-meter Giant Magellan Telescope, and the 39-meter European Extremely Large Telescope.
But before turning this laser beacon on, Clark says we should consider some safety issues. The beam — even though it’s invisible — could hurt anyone’s vision if they looked in the wrong direction. It’s even powerful enough to mess up cameras of any orbiting spacecraft going through the beam’s path. One solution could be to build the laser on the moon. Clark emphasizes, though, that more solutions could come from other work — he was just interested, for now, if seeing if the technology was possible.