Short answers, pulled from the story.
The Pioneer program was two successive series of United States uncrewed space probes. The first series, 1958-1960, targeted the Moon and interplanetary space. The second, 1965-1992, explored interplanetary space weather, Jupiter, Saturn, and Venus.
Stephen A. Saliga, chief designer of Air Force exhibits at Wright-Patterson AFB, proposed the name "Pioneer" at a briefing in 1958. He chose it partly to outmaneuver the Army, which had been publicly branding itself as "Pioneers in Space" after launching its Explorer satellite.
Pioneer 10 and Pioneer 11 were the first two of five artificial objects to achieve the escape velocity needed to leave the Solar System. Pioneer 10 launched in March 1972 and Pioneer 11 launched in April 1973.
Each probe carries a golden plaque engraved with an image of a man and a woman alongside information about the origin and creators of the spacecraft. The plaque was intended for any extraterrestrial intelligence that might one day find the probe drifting through interstellar space.
Pioneers 6-9, launched between December 1965 and November 1968, formed an interplanetary space weather network in solar orbit. Placed at different distances from the Sun, they could detect solar activity on the Sun's far side several days before Earth-based observatories could see it. Pioneer 9 went inactive in 1983.
The Pioneer Venus Orbiter launched in May 1978 and the Pioneer Venus Multiprobe launched in August 1978. The Multiprobe carried a 300-kilogram parachuted Large Probe and three 75-kilogram impactor probes designated the North, Night, and Day Probes, together conducting a detailed multi-point study of Venus.