Pioneer plaque The Pioneer plaques are a pair of gold - anodized aluminium plaques which were placed on board the 1972 Pioneer 10 and 1973 Pioneer 11 spacecraft , featuring a pictorial message , in case either Pioneer 10 or 11 are intercepted by extraterrestrial life . The plaques show the nude figures of a human male and female along with several symbols that are designed to provide information about the origin of the spacecraft. [1] The Pioneer spacecraft were the first human-built objects to leave the solar system . The plaques were attached to the spacecraft's antenna support struts in a position that would shield them from erosion by stellar dust . Physical properties Material: 6061 T6 gold-anodized aluminum Width: 229 mm (9 inches) Height: 152 mm (6 inches) Thickness: 1.27 mm (0.05 inches) Mean depth of engraving : 0.381 mm (0.015 inches) Mass: approx. 0.120 kilograms Wikipedia At the far right, the ...