The Pioneer Venus project was part of the Pioneer program consisting of two spacecraft, the Pioneer Venus Orbiter and the Pioneer Venus Multiprobe, launched to Venus in 1978. The program was managed by NASA's Ames Research Center. The Pioneer Venus Orbiter entered orbit around Venus on December 4, 1978, and performed observations to characterize the atmosphere and surface of Venus. It continued to transmit data until October 1992. The Pioneer Venus Multiprobe deployed four small probes into the Venusian atmosphere on December 9, 1978. All four probes transmitted data throughout their descent to the surface. One probe survived the landing and transmitted data from the surface for over an hour. Overview The Pioneer mission consisted of two components, launched separately: an orbiter and a multiprobe. Orbiter The orbiter was launched on May 20, 1978 on an Atlas-Centaur rocket. The orbiter's mass was . The Pioneer Venus Orbiter was inserted into an elliptical orbit around Venus on December 4, 1978. It carried 17 experiments (with a total mass of 45 kg): a cloud photopolarimeter to measure the vertical distribution of the clouds a surface radar mapper to determine topography and surface characteristics an infrared radiometer to measure IR emissions from the Venus atmosphere an airglow ultraviolet spectrometer to measure scattered and emitted UV light a neutral mass spectrometer to determine the composition of the upper atmosphere a solar wind plasma analyzer to measure properties of the solar wind a magnetometer to characterize the magnetic field at Venus an electric field detector to study the solar wind and its interactions an electron temperature probe to study the thermal properties of the ionosphere an ion mass spectrometer to characterize the ionospheric ion population a charged particle retarding potential analyzer to study ionospheric particles two radio science experiments to determine the gravity field of Venus a radio occultation experiment to characterize the atmosphere an atmospheric drag experiment to study the upper atmosphere a radio science atmospheric and solar wind turbulence experiment a gamma ray burst detector to record gamma-ray burst events In May 1992 the orbiter began the final phase of its mission, in which the periapsis was held between 150 and 250 km until the fuel ran out and atmospheric entry destroyed the spacecraft in August 1992. Multiprobe The Pioneer Venus Multiprobe was launched on August 8, 1978 on an Atlas-Centaur rocket. It consisted of a 290 kg bus which carried one large