Developments into a powerful laser could let aliens know where we are
If there are aliens out there, a researcher in the United States thinks he might be able to find them.
James Clark, a researcher at the Massachusetts Institute of Technology, says he believes scientists would be in a position now to produce a laser beacon detectable up to 20,000 light years away – effectively designed to say to aliens idly gazing across the galaxy, “Hey! Over here!”
His feasibility study posits that a one to two-megawatt laser focused through a 30 to 45-metre telescope and aimed into space would emit radiation strong enough to be distinguishable from the sun’s infrared energy. Aliens in a neighbouring solar system might then spot it and come over to say hi.
Of course, in intergalactic terms, neighbouring is still quite far away. Proxima Centauri, the nearest star to Earth, has planets around it and is about four light years away; Trappist-1, which has seven planets in its orbit, three of which are potentially habitable, is around 40 light years away.
But as technology progresses, Clark, a graduate student in MIT’s Department of Aeronautics and Astronautics, says: “we can be more certain that, if ET is phoning, we will detect it.”
He even reckons we could send a Morse code-style message by using pulses, as long as the aliens are reasonably well versed in telegraphy – and don’t mind waiting years (literally) for the reply to get there.
Clark’s research, which was part of his studies, was published earlier this month in The Astrophysical Journal.
“If we were to successfully close a handshake and start to communicate, we could flash a message which would get there in just a few years,” he said.
“This would be a challenging project but not an impossible one. The kinds of lasers and telescopes that are being built today can produce a detectable signal, so that an astronomer could take one look at our star and immediately see something unusual about its spectrum. I don’t know if intelligent creatures around the sun would be their first guess, but it would certainly attract further attention.”
It’s true that the necessary technology is within practical reach. A 30-metre telescope is considerably larger than anything we have now, but the 39-metre European Extremely Large Telescope is under construction in Chile. The now-defunct US Air Force YAL-1 Airborne Laser, which was meant to fly aboard a military jet and shoot ballistic missiles out of the sky, had the equivalent power to the laser Clark says would be required.
There are other concerns, however, such as the laser potentially damaging people’s eyes if they looked directly towards it — even though the beam would be invisible to the naked eye, it would still be extremely strong (around 800 watts per square metre, compared with the sun, which generates about 1,300 watts per square metre). The laser could also scramble cameras on board spacecraft which passed through it. But Clark has a solution for this too – put it on the far side of the moon, where in his words, “no one’s living or orbiting much”.
In fact, maybe there are already aliens out there doing this now. Would we know? We’d have to have a telescope a metre long or more directed at the exact source of the beam, which Clark describes as “vanishingly unlikely”. However, imaging tools used to study gases on other planets for signs of life could pick up the signals too. The little green men might already be typing out “Hey. Wanna hang?” as we speak.
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