What messages have we sent to space for aliens?

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Are we alone in the galaxy? Many wonder. In recent decades, some have even attempted to report our presence to possible extraterrestrials. Here are the different messages sent.

We start in 1962. At the time, Soviet researchers pointed a radio transmitter at Venus and greeted the planet in Morse code. This message consisted of three words: Mir (“peace” and “world” in Russian), Lenin and SSSR (acronym in the Latin alphabet for the Cyrillic name of the Soviet Union). The attempt was purely symbolic. More than anything, the Soviets were testing a whole new radar aimed at mapping objects in the Solar System.

In 1969, a commemorative plaque was then placed on the moon by the crew of Apollo 11. Attached behind the rungs of the lunar module, it displays a representation of the Earth and a message of peace from US President Nixon.

Pioneer design

Another attempt with a gold and aluminum plate attached to the Pioneer 10 probe, launched in April 1972.

Developed by Carl Sagan and Frank Drake and drawn by Linda Sagan, it represents a naked couple supposed to represent humanity (the right hand of the man is raised in sign of salute), a hydrogen atom and a drawing of the Solar system (with the placement of the Earth). Also shown are the trajectory of the probe and its size compared to our stature.

Finally, it represents the rhythm of emissions of fourteen pulsars. Concretely, the lengths of the lines show the relative distances of these objects from the Sun. The position of the Earth could therefore be calculated by triangulation.

The Pioneer Plate. Credit: Oona Räisänen

Arecibo’s message

Two years later, in 1974, a team of scientists, still including astronomers Frank Drake and Carl Sagan, this time transmitted a radio message from the Arecibo Observatory in the direction of Messier 13. This is a star cluster found at about 25,000 light years away. In other words, if the message finds recipients, we won’t have an answer for at least 50,000 years !

The image, sent in binary code, represents a human silhouette, our average height, as well as the number of humans on Earth in 1974. The Solar System also appears, a double helix DNA structure, an atom model. of carbon and a drawing of the Arecibo radio telescope.

The Arecibo message, sent in 1974 from the Arecibo Observatory. Colors have been added to better see the different parts. Credit: Arne Nordmann

Voyager’s Gold Record

We have not only relied on the radio to communicate with aliens, but also launched vessels containing terrestrial artifacts. In the Voyager 1 and 2 probes, launched in 1977 to explore the confines of our Solar System, a gold record containing music, ambient sounds of the Earth and 116 images of our planet and the Solar System.

These two discs are also accompanied by a stylus allowing their reading and a source of uranium 238 (radioactive half-life of the order of 4.5 billion years) making it possible to determine the time elapsed since their launch.

The golden jacket and its multimedia disc placed on board the Voyager probes. Credit: NASA / JPL

It remains to be seen whether all these messages can be found and decrypted. According to many specialists, the chances of this happening are almost zero. This outcome depends, of course, on whether or not there are extraterrestrials “in the range” of our messages. This life would also have to listen carefully to the radio signals and understand enough mathematics to interpret them.

Finally, the messages we sent tend to assume that these aliens feel the universe the same way we do: with hearing and seeing. However, this may simply not be the case.

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