Pioneer 6, 7, 8, and 9

Pioneer 6, 7, 8, and 9 were space probes in the Pioneer program, launched between 1965 and 1969. They were a series of solar-orbiting, spin-stabilized, solar cell- and battery-powered satellites designed to obtain measurements on a continuing basis of interplanetary phenomena from widely separated points in space. They were also known as Pioneer A, B, C, and D. The fifth (Pioneer E) was lost in a launch accident, and therefore did not receive a numerical designation. Pioneers 6, 7, 8, and 9 were created to make the first detailed, comprehensive measurements of the solar wind, solar magnetic field and cosmic rays. They were designed to measure large scale magnetic phenomena and particles and fields in interplanetary space. Data from the vehicles have been used to better understand stellar processes and the structure and flow of the solar wind. The vehicles also acted as the world's first space-based solar weather network, providing practical data on solar storms which affect communications and power on Earth. The experiments studied the positive ions (cations) and electrons in the solar wind, the interplanetary electron density (radio propagation experiment), solar and galactic cosmic rays, and the Interplanetary Magnetic Field. The spacecraft were important collectors of heliophysics and space weather data. In conjunction with other spacecraft these, for the first time, enabled spaceborne observations to be combined with terrestrial observations on the ground and from sounding balloons. Pioneer 9 in early August 1972 recorded significant observations of one of the most potent solar storms ever recorded, and the most hazardous to human spaceflight during the Space Age. Each craft was identical. They were spin-stabilized diameter × tall cylinders with a long magnetometer boom and solar panels mounted around the body. The main antenna was a high-gain directional antenna. The spacecraft were spin-stabilized at about 60 RPM, and the spin axis was perpendicular to the ecliptic plane and pointed toward the south ecliptic pole.