A new MIT study proposes to create a cosmic beacon, with laser technology available, strong enough to attract attention to Earth from 20,000 light years.
The research, which author James Clark calls 'feasibility study', appears in the Astrophysical Journal. The findings suggest that, if a 1 to 2 megawatt high-power laser would be focused through a Massive telescope from 30 to 45 meters and going into space, the combination would produce a beam of infrared radiation strong enough to stand out from the sun's energy.
Such a signal could be detected by astronomers from other civilizations who were doing a brief study of our section of the Milky Way, especially if those astronomers live in nearby systems, such as near Proxima Centauri, the closest star to Earth, or TRAPPIST- one, a star about 40 light years away that houses seven exoplanets, three of which are potentially habitable.
If the signal is detected in any of these nearby systems, according to the study, the same megawatt laser could be used to send a brief message in the form of pulses similar to Morse code.
"If we had to successfully close a handshake and start communicating, we could send a message, to a data rate of a few hundred bits per second, which would come in a few years, "says Clark, a graduate student in the Department of Aeronautics and Astronautics at MIT and the author of the study.
The notion of such a beacon that attracts other advanced civilizations may seem preposterous, but Clark says that the feat can be done with a combination of technologies that exist now and could be developed in the short term.
"This would be a challenging project but not impossible," says Clark. "The types of lasers and telescopes that are being built today they can produce a detectable signal, so an astronomer could take a look at our star and immediately see something unusual in its spectrum. "
Clark analyzed combinations of lasers and telescopes of various watts and sizes, and found that a laser of 2 megawatts, aimed through a 30-meter telescope, could produce a signal strong enough to be easily detected by astronomers in Proxima Centauri b, a planet orbiting our nearest star, 4 light-years away.
Similarly, a 1-megawatt laser, directed through a 45-meter telescope, would generate a clear signal in any survey conducted by astronomers within the TRAPPIST-1 planetary system, some 40 light-years away. He estimated that any of the configurations could produce a generally detectable signal up to 20,000 light years away.
Both scenarios would require a laser and telescope technology that has already been developed or is within practical reach. For example, Clark calculated that the required laser power of 1 to 2 megawatts is equivalent to that of the US Air Force's Airborne Laser, a one-megawatt laser now retired. that he had to fly aboard a military plane for the purpose of firing ballistic missiles into space. He also discovered that while a 30-meter telescope dwarfs any existing observatory on Earth today, there are plans to build such massive telescopes in the near future, including the 24-meter Magellan Giant Telescope and the 39-meter Extremely Large European Telescope. . Both are currently under construction in Chile.
Clark anticipates that, like these massive observatories, a laser beacon should be built on the top of a mountain, to minimize the amount of atmosphere that the laser I would have to penetrate before going out into space.
He recognizes that a megawatt laser would come with some security problems. A beam of this type would produce a flow density of approximately 800 watts of power per square meter, which approximates that of the sun, which generates about 1,300 watts per square meter. While the beam would not be visible, it could still damage people's vision if they looked directly at it.