Regardless of the potential effects on humanity's future, researchers from MIT are studying how to use existing laser technology to beam a beacon strong enough to attract attention from as far as 20,000 light years (LY) away.

The study suggests that a high-powered 1 to 2 MW laser focused through a 30 to 45 m telescope and aimed into space would produce a beam of infrared radiation that is distinct from the sun’s energy. This signal could be detectable by alien astronomers performing surveys of the Milky Way, especially if they live in nearby systems such as Proxima Centauri, the star closest to Earth, or Trappist-1, a 40 LY away sun that hosts seven exoplanets, three of which may be habitable.

Researchers said this beacon could send a brief message in the form of pulses, similar to Morse code.

“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 student in MIT’s Department of Aeronautics and Astronautics and author of the study.

Clark said the beacon could be crafted from a combination of technologies that exist now and could be developed in the near-term. Clark researched different lasers and telescopes before finding the right combination of laser wattage and telescope size that might produce a signal distinguishable from the sun. He found that a 2 MW laser pointed through a 30 m telescope would be sufficient in pointing a beacon to Proxima Centauri, while a 1 MW laser through a 45 m telescope would send a clear signal to the Trappist-1 planetary system. Both scenarios would require laser and telescope technology that is available or within practical reach.

For example, the defunct U.S. Air Force Airborne Laser — initially built to shoot ballistic missiles out of the sky — has the power of 1 to 2 MW, but a 30 m telescope dwarfs any existing observatory on Earth today. However, there are plans to build such massive telescopes in the near future, such as the 24 m Giant Magellan Telescope and the 39 m European Extremely Large Telescope, currently under construction in Chile.

Clark acknowledged safety issues with such a laser beacon and the possibility it could damage vision of nearby locals or adjacent property, but there are possible solutions as well.

“If you wanted to build this thing on the far side of the moon where no one’s living or orbiting much, then that could be a safer place for it,” Clark said. “In general, this was a feasibility study. Whether or not this is a good idea, that’s a discussion for future work.”

The full research can be found in The Astrophysical Journal.

To contact the author of this article, email pbrown@globalspec.com