The Pioneer series of spacecraft performed first-of-their-kind explorations of the Sun, Jupiter, Saturn and Venus. The different missions had little in common except that they all paved the way for later in-depth investigations, and were all spin stabilized.
Pioneer 0, 1, and 2 were the United States' first lunar attempts. These identical spacecraft, which all failed to meet their lunar objectives, were followed by Pioneer 3 and 4, which succeeded in becoming America's first successful lunar missions. Pioneer 5 provided the first maps of the interplanetary magnetic field. Pioneers 6,7,8, and 9 were the world's first solar monitoring network and provided warnings of increased solar activity which could affect Earth orbiting satellites and ground systems. The twin Pioneer 10 and 11 vehicles were the first spacecraft to ever visit Jupiter and Saturn. The craft performed a wide variety of scientific observations of the two planets and returned environmental data that was used during the design of the more sophisticated Voyager probes. The Pioneer Venus mission, consisting of the Pioneer Venus Orbiter (Pioneer 12) and Pioneer Venus Multiprobe (Pioneer 13), was the United States' first long-term mission to observe Venus and studied the structure and composition of the Venusian atmosphere. The mission also provided the first radar map of the planet's surface.