NASA has launched four probes into space to communicate with extraterrestrials. Along with that it is used for the study of the universe, the planets of the solar system and so on.
Voyager 1 and 2 in 1977. Before this, they were Pioneer 10 in 1972 and Pioneer 11 in 1973.
(Out of which Voyager 1 is the farthest man-made object from Earth. It is now about 2100 million kilometers away.)
These probes are capable of being understood by other aliens in the future
In these, hints were given about the earth and man. Ancient pictorial languages were used in them. Voyager has a disk made of a gold alloy that records Earth’s sounds, images, and videos.
It also has human geometric figures, earth coordinates, and hints of culture.
A source of uranium-238 with a radioactivity of about 0.00026 microcuries is used to electroplate the cover of the record that encodes the message.
Because it takes 4.51 billion years for half of uranium-238 to decay. This will help the message to remain intact for a long time.
Among these, the language used to refer to the earth is “hieroglyphics”.
Hieroglyphics is an ancient Egyptian language using pictures.
Both spacecraft are sent in opposite directions from Earth.
Radio signals are still being received from these.
Once our message reaches another planet with life presence we can wait for their reply.