The Pioneer Venus Orbiter entered orbit around Venus on December 4, 1978, and performed observations to characterize the atmosphere and surface of Venus. What was Pioneer Venus 1?

The Pioneer Venus 1 (also known as the Pioneer Venus orbiter) was the first of a two-spacecraft orbiter-probe combination designed to conduct a comprehensive investigation of the atmosphere of Venus. The Pioneer Venus Project The Pioneer Venus Project's main objective was to investigate the solar wind in the Venusian environment, map the planet's surface through a radar imaging system and study the characteristics of the upper atmosphere and ionosphere. All instruments and spacecraft subsystems were mounted on the forward end of the cylinder, except … The spacecraft was a solar-powered cylinder about 8.3 feet (250 centimeters) in diameter. NASA's Pioneer Venus 1 was the first of a two-spacecraft orbiter-probe combination designed to study the atmosphere of Venus.
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 Pioneer Venus Orbiter was inserted into an elliptical orbit around Venus on December 4, 1978. The Orbiter was a flat cylinder 2.5 m in diameter and 1.2 m high. The probe found Venus to be generally smoother than Earth, … The second spacecraft was launched a few months later.. Pioneer Venus 1 used radar to map the surface of Venus. The orbiter spacecraft was launched May 20, 1978. It was the first American spacecraft to orbit Venus. The program was managed by NASA's Ames Research Center..