 pioneer 6, 7, 8, and 9 were space probes in the pioneer program. together, they formed 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. == purpose == 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 has 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 impact 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. == vehicle description == each craft was identical, with an on-orbit dry mass of 146&nbsp;kg. they were spin-stabilized 0.94 m diameter Ã 0.81 m tall cylinders with a 1.8 m 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 1 hz, and the spin axis was perpendicular to the ecliptic plane and pointed toward the south ecliptic pole. instruments:  * solar wind plasma faraday cup (6,7) * cosmic-ray telescope (6,7) * electrostatic analyzer (6,7,8) * superior conjunction faraday rotation (6,7) * spectral broadening (6) * relativity investigation (6)  * uniaxial fluxgate magnetometer (6) * cosmic-ray anisotropy (6,7,8,9) * celestial mechanics (6,7,8,9) * two-frequency beacon receiver (6,7,8,9) * single-axis magnetometer (7,8) * cosmic dust detector (8,9)  * cosmic ray gradi
Artificial_satellites_orbiting_the_Sun Derelict_satellites Derelict_space_probes Missions_to_the_Sun Pioneer_program