Concept
Pioneer 11 (also known as Pioneer G) is a NASA robotic space probe launched on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter Saturn, the second to fly through the asteroid belt, and the second to fly by Jupiter. Later, Pioneer 11 became the second of five artificial objects to achieve an escape velocity allowing it to leave the Solar System. Due to power constraints and the vast distance to the probe, the last routine contact with the spacecraft was on September 30, 1995, and the last good engineering data was received on November 24, 1995. Approved in February 1969, Pioneer 11 and its twin probe, Pioneer 10, were the first to be designed for exploring the outer Solar System. Yielding to multiple proposals throughout the 1960s, early mission objectives were defined as: Explore the interplanetary medium beyond the orbit of Mars Investigate the nature of the asteroid belt from the scientific standpoint and assess the belt's possible hazard to missions to the outer planets. Explore the environment of Jupiter. Subsequent planning for an encounter with Saturn added many more goals: Map the magnetic field of Saturn and determine its intensity, direction, and structure. Determine how many electrons and protons of various energies are distributed along the trajectory of the spacecraft through the Saturn system. Map the interaction of the Saturn system with the solar wind. Measure the temperature of Saturn's atmosphere and that of Titan, the largest satellite of Saturn. Determine the structure of the upper atmosphere of Saturn where molecules are expected to be electrically charged and form an ionosphere. Map the thermal structure of Saturn's atmosphere by infrared observations coupled with radio occultation data. Obtain spin-scan images of the Saturnian system in two colors during the encounter sequence and polarimetry measurements of the planet. Probe the ring system and the atmosphere of Saturn with S-band radio occultation.
