NASA's mission of two spacecraft to the planet Venus in 1978, an orbiter launched in May and a multiprobe launched in August. The first spacecraft went into orbit around Venus on 4 December, carrying 12 instruments that included a gamma-ray burst detector and a surface radar-mapper. The orbiter's primary objectives were to investigate the solar wind in Venus's environment, study the planet's upper atmosphere and ionosphere, and map the topography of the surface. Designed to operate for one Venusian year (243 days), the orbiter and most of its instruments lasted until 1992 when it fell into the atmosphere. The second spacecraft encountered Venus on 9 December and separated into five pieces: the transporter, an atmospheric entry probe, and three identical small probes. All entered the atmosphere and sent back data for an hour as they descended.

http://nssdc.gsfc.nasa.gov/planetary/pioneer_venus.html Straightforward guide to the Pioneer Venus mission. As well as the descriptions of the spacecraft instruments and data, there are artists' views of the spacecraft. The page also provides links to many important Venus exploration resources.