Contact ET with High-Power Laser & Telescope?

                          
Image of the Unit Telescope 4 (UT4) of the European Southern Observatory's Paranal Observatory in the Atacama Desert of northern Chile. This was the first observatory to use multiple lasers to be the most powerful laser guide stars ever used in astronomy. Now, two space researchers propose using a mega-watt laser, through a large telescope, to signal possible astronomers in other star systems.
(Image Sources: European Southern Observatory, Wikipedia.org)

By Glenn A. Walsh

Reporting for SpaceWatchtower

Could a high-power laser, focused through a telescope, attract the attention of astronomers in distant star systems? Two scientists at the Massachusetts Institute of Technology (MIT) think so.

A paper published in the Astrophysical Journal by MIT scientists James Clark and Dr. Kerri Cahoy proposes that a 1 or 2 mega-watt laser, focused into Outer Space using a 30-to-45-meter telescope, could be enough to signal astronomers as far away as 20,000 light-years!

The idea is that such a strong laser-light would produce a beam of infrared radiation strong enough to stand-out next to the bright light coming from our local star, the Sun. So, if alien astronomers happened to use their telescopes to look toward our Solar System, they would notice an unusually bright light in addition to the light from our Sun.

Mr. Clark, the lead author who is a graduate student in the MIT Department of Aeronautics and Astronautics, told Sci-News.com, “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.”

Of course, this type of communication would only be practical for short distances. If the astronomers were as far as 20,000 light-years away, they would not receive the signal until 20,000 years in the future. And, if they would immediately return such a signal to us, it would take 40,000 years for us to receive the reply!

The first problem with making such a planetary beacon a reality is building lasers and telescopes to the large size requirements necessary. The U.S. Air Force's Airborne Laser, which has been tested as a way to shoot-down ballistic missiles from a military jet, is one example of a laser which could be strong enough for a planetary beacon.

Although no telescope is currently large enough for such a planetary beacon, 24-meter and 39-meter telescopes now under construction in Chile may be large enough for such a project. The Large Magellan Telescope (24-meter) is being built by a consortium of countries led by the United States, and the European Extremely Large Telescope (39-meter) is being built by the European Southern Observatory.

Do extra-terrestrial astronomers, now, have such a planetary beacon which we could find? The MIT scientists determined that a 1-meter telescope on Earth could distinguish such a beacon. But to find it, the telescope would probably have to look directly at the beacon.

Mr. Clark told Sci-News.com, “It is vanishingly unlikely that a telescope survey would actually observe an extraterrestrial laser, unless we restrict our survey to the very nearest stars.”

Internet Links to Additional Information ---

"Megawatt-Class Lasers from Earth Could Attract Alien Astronomers, Says New Study."
Sci-News.com 2018 Nov. 9.
Link >>> http://www.sci-news.com/astronomy/megawatt-class-lasers-alien-astronomers-06591.html

Clark, James R. & Kerri Cahoy. 2018. Optical Detection of Lasers with Near-term Technology at Interstellar Distances. ApJ 867, 97; doi: 10.3847/1538-4357/aae380
Link >>> http://iopscience.iop.org/article/10.3847/1538-4357/aae380

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Friday, 2018 December 7.

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gaw

Glenn A. Walsh --- < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
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Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991. Formerly Trustee of the Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
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