The State of SETI and CETI Searches

The SETI project (Search for Extraterrestrial Intelligence) arose in the United States in 1984 on the basis of this concept. Initially financed by NASA, it func-

Fig. 9.24 The radio telescope at Arecibo in Puerto Rico

tions today on private funding. It represents a vast international collaboration, and finances numerous research projects, primarily oriented towards listening for possible 'intelligent' signals emitted in the cosmos. Although the search may have been unsuccessful so far, it nevertheless bears witness to the collective interest in this quest, which goes far beyond the scientific community. Note that the SETI project has an equivalent in the visible region, OSETI, which may benefit in future from technological advances linked to the development of high-powered pulsed laser systems.

Beyond simple monitoring, the research projects known as CETI (Communication with Extraterrestrial Intelligence) pose the question of the methods necessary to initiate contact with any possible extraterrestrial civilization. The first example is the coded message sent by Frank Drake, using the Arecibo radio telescope in 1974, in the direction of the globular cluster M13. Two frequencies were selected, close to 2380 MHz. The message was coded in 1679 bits to generate an image of 23 by 73 pixels (Fig. 9.25). The Arecibo message is of symbolic rather than real interest, but it represents a classic example of the encoding of information being sent to an unknown recipient.

numbers 1 to 10 number labels atomic numbers for hydrogen, carbon. nitrogen, oxygen and phosphorus formulas for sugars and bases in nucleolides of DNA

number of nucleolides in DNA

double helix of DNA human being height of human being human population of Earth Solar system (Earth displaced towards human being) Arecibo telescope transmitting message diameter of telescope (b) (c)

formulas for sugars and bases in nucleolides of DNA

Fig. 9.25 The binary message sent by the Arecibo telescope in 1974

Fig. 9.25 The binary message sent by the Arecibo telescope in 1974

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