Pioneer 10 and 11 Spacecraft: The Pioneer 10 and 11 spacecraft were the first human-made objects to leave the Solar System. They were launched in the early 1970s to study the outer Solar System and eventually become the first human-made objects to leave the heliosphere, the bubble of charged particles from the Sun.
Interstellar Communication: Interstellar communication refers to the transmission of messages between planetary systems. The Pioneer plaques were an attempt to communicate information about the origin of the spacecraft to any potential intelligent life that may encounter them in interstellar space.
Extraterrestrial Intelligence: Extraterrestrial intelligence refers to the hypothetical existence of intelligent life forms on planets other than Earth. The Pioneer plaques were designed to provide information about the origin of the spacecraft and its creators, in the event that they were encountered by such intelligent life forms.