P-3 Atlas-Able 4, Atlas-Able 4B, Pioneer X Pioneer 5 Pioneer P-2, Thor-Able 4, Pioneer V Pioneer P-30 Atlas-Able 5A, Pioneer Y Lunar probe Failed to achieve lunar orbit. September 25, 1960 Pioneer P-31 Atlas-Able 5B, Pioneer Z Lunar probe Lost in upper stage failure. December 15, 1960 Juno II lunar probes (1958–1959) Pioneer 3 – Lunar flyby, missed Moon due to launcher failure December 6, 1958 Pioneer 4 – Lunar flyby, achieved Earth escape velocity, launched March 3, 1959 Later missions (1965–1978) Five years after the early Able space probe missions ended, NASA Ames Research Center used the Pioneer name for a new series of missions, initially aimed at the inner Solar System, before the flyby missions to Jupiter and Saturn. While successful, the missions returned much poorer images than the Voyager program probes would five years later. In 1978, the end of the program saw a return to the inner Solar System, with the Pioneer Venus Orbiter and Multiprobe, this time using orbital insertion rather than flyby missions. The new missions were numbered beginning with Pioneer 6 (alternate names in parentheses). Interplanetary weather The spacecraft in Pioneer missions 6, 7, 8, and 9 comprised a new interplanetary space weather network: Pioneer 6 (Pioneer A) – launched December 1965 Pioneer 7 (Pioneer B) – launched August 1966 Pioneer 8 (Pioneer C) – launched December 1967 Pioneer 9 (Pioneer D) – launched November 1968 (inactive since 1983) Pioneer E – lost in launcher failure August 1969 Pioneer 6 and Pioneer 9 are in solar orbits with 0.8 AU distance to the Sun. Their orbital periods are therefore slightly shorter than Earth's. Pioneer 7 and Pioneer 8 are in solar orbits with 1.1 AU distance to the Sun. Their orbital periods are therefore slightly longer than Earth's. Since the probes' orbital periods differ from that of the Earth, from time to time, they face a side of the Sun that cannot be seen from Earth. The probes can sense parts of the Sun several days before the Sun's rotation reveals it to ground-based Earth orbiting observatories. Outer Solar System missions Pioneer 10 (Pioneer F) – Jupiter, interstellar medium, launched March 1972 Pioneer 11 (Pioneer G) – Jupiter, Saturn, interstellar medium, launched April 1973 Pioneer H – proposed out-of-ecliptic mission for 1974, never launched. Is identical to Pioneers 10 and 11. Venus project Pioneer Venus Orbiter (Pioneer Venus 1, Pioneer 12) – launched