In between 1965 and 1968, Pioneers 6-9 were launched into Solar Orbit and their prime mission was accomplished years ago. The Pioneer space probes were launched in the Orbit to make comprehensive measurements of interplanetary magnetic fields and the flow and the structure of the solar wind. It was one of the first space-based solar weather network providing data on solar storms which impacts communications and power systems on the Earth.
It's been 50 years since the Delta E rocket which carried Pioneer 8, flew from Cape Canaveral Florida and entered the solar orbit with a mean radius of 1.1 Astronomical Units(AU) ( 1 AU is the average distance between the Sun and the Earth) or slightly outside the Earth's orbit. The probe was equipped with the eight instruments which were solar powered and the findings were correlated with the information gathered by the other Pioneers. During the Apollo lunar missions, the fleet of pioneers provided hourly updates on the Sun's activity. The pioneer provided early warnings on the unusual blasts of intense showers of solar protons which could have the life-ending situation of astronauts.
The fleet worked far more than anticipated, and Pioneer 8 sent useful data on 8 June 2001 which was the last contact. The probe helped to understand the interplanetary space environment and did an astounding job during Apollo lunar missions.