The design of a pictorial plaque, attached to the exterior of the Pioneer 10 & 11 spacecrafts, indicating their origin in case they might one day be examined by another intelligent species. The dumb-bell" symbol at top left represents a hydrogen atom, the most common element in the Universe. Below, 14 lines radiate from our Sun to the relative positions of 14 Pulsars - cosmic sources of radio energy. Human figures, the man's hand raised in goodwill, are set against the spacecraft to give scale. At bottom is a plan of the Solar System, showing the route of a Pioneer spacecraft on the early stages of its journey from Earth. The frequency of each Pulsar at the time of launch is quoted in binary, relative to that of the Hydrogen atom with its "1" unity symbol. The"