The members of the SETI program have just released the results of the largest and most accurate extraterrestrial techno-signature research campaign. The researchers returned empty-handed but are not discouraged, because we have only scratched the surface of the world of exoplanets.
In September 1959, the journal Nature published a visionary article by Giuseppe Cocconi, who played an important role in setting up the Proton Synchrotron of CERN, and Philip Morrison, who had participated in the Manhattan Project.
The two physicists held the following reasoning: if advanced extraterrestrial civilizations exist in the galaxy, they could communicate with each other or with their colonies using radio waves. Considering the wavelengths most conducive to the distant transmission of clear signals, despite the radio galactic background, they had concluded that the most suitable radio band was the narrow one, surrounding the 21-centimeter wavelength.
In addition, this band corresponds to a so-called transition hyperfine in the atom of hydrogen neutral, the most abundant element in the universe. So it was a good way to establish a standard of communication, naturally adopted by any developed civilization.
A young radio astronomer, Frank Drake, had reached similar conclusions. When he was posted to the Green Bank radio telescope, on April 8, 1960 he launched the Ozma project, named after a princess from Oz. For two two-month periods Drake and his colleagues listened with the Green Bank radio telescope to two Sun-like stars less than 15 light-years away, Tau Ceti and Epsilon Eridani.
The result was negative. Sixty years after Drake, still alive, the SETI program is still relevant. In 2015, it received a major boost through the project Breakthrough Initiative billionaire Yuri Milner. Backed at the time by Stephen Hawking as well as Kip Thorne, the Nobel Prize in physics and science advisor of the film Interstellar, and Ann Druyan, the widow of Carl Sagan, he was aiming to give 100 million dollars in ten years to the Seti program.
More than 1,000 stars tuned on billions of frequencies
The Breakthrough Initiative project actually comes in two parts. The first and most important consists of trying to detect ET civilization programs in the radio field but also in the form of laser pulses; the second launches a $1 million competition. It is open to all and consists in proposing a message to one of the possible civilizations. It is therefore in line with the Golden Record but also the famous message of Arecibo, concocted and sent by Franck Drake and Carl Sagan, using the great Arecibo radio telescope.
Today, the members of the Breakthrough Listen project make an initial assessment of three years of ET techno signature hunting, again with the Green Bank radio telescope in the United States but also that of Parkes in Australia. The Automated Planet Finder Telescope (APF), a 2.4 meter fully robotic optical telescope at the Lick Observatory (California) already used to search for exoplanets, also entered the dance. Two articles on arXiv report on it. This is the most important research done by the SETI program in its history. The data collected, which has already been the subject of analysis of the researchers, is also made public.
In total, 1,327 stars in a sphere whose radius is about 160 light-years around the Solar System have been listened to and observed. The amount of data collected is equivalent to one petabyte, which is approximately 1,600 years of continuous listening from your favorite online music service.
For Danny Price, one of the radio astronomers at the head of this project: “This release of data is an important step for the Breakthrough Listen team. We analyzed thousands of hours of observations of nearby stars on billions of frequency channels. We did not find any evidence of extraterrestrial artificial signals, but that does not mean that there is no intelligent life out there: we may not have looked at the right place yet, nor seen quite carefully.”
The quest for one of the grails of exobiology will, therefore, continue, especially with the MeerKAT program in South Africa, which should concern this time a million stars.
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