An MIT student states that contemporary laser technology can in principle be used to send a laser beam into the universe as a kind of beacon to attract the attention of extraterrestrial astronomers at a distance of up to 20,000 light-years.
According to American MIT student James Clark, it is possible to aim a powerful laser of one to two megawatts through a telescope with a mirror of 30 to 45 meters. That would generate so much infrared radiation that the beam is strong enough to distinguish itself from the radiation from our sun.
In this way, aliens could still detect the beacon at distances of up to 20,000 light-years from Earth, especially if intelligent life happens to exist on some relatively nearby exoplanets, for example in the Trappist-1 system, which is 40 light-years away. is located. The laser beam is not just intended as a beacon. According to the study, the laser in the form of pulses can also be used to communicate short messages, much like Morse code.
The idea seems far-fetched and more of a science fiction movie, but Clark points out that a one- to two-megawatt laser is comparable to the US Air Force’s Airborne Laser. This never got off the ground, but the idea was to put a huge laser in a modified Boeing 747 to shoot ballistic missiles out of the sky. In addition, the Extremely Large Telescope in Chile will have a mirror with a diameter of 39 meters.
By shooting such a laser beam from Earth into space, problems can arise on Earth. The invisible laser beam can reach a flux of 800 watts per m², which is not so far away from the 1300 watts per m² of the sun. This means that people could incur damage to their eyes if they looked straight into the beam. Cameras in spacecraft that happen to fly through the jet also face problems. Therefore, for safety’s sake, Clark thinks it’s best to build the laser rig on the far side of the moon.
Clark acknowledges that this research is not a direct call to build such a laser installation; his study can mainly be regarded as a feasibility study. “Whether it’s a good idea is a discussion for the future,” Clark says. The research was published in the scientific journal The Astrophysical Journal under the title Optical Detection of Lasers with Near-term Technology at Interstellar Distances.