Pioneer Venus project

[1][3] The Pioneer Venus Multiprobe deployed four small probes into the Venusian atmosphere on December 9, 1978.

The Pioneer mission consisted of two components, launched separately: an orbiter and a multiprobe.

It carried 17 experiments (with a total mass of 45 kg):[3] 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.

The Pioneer Venus large probe was about 1.5 m in diameter and equipped with 7 science experiments.

With no heat shield or parachute, the bus made measurements only to about 110 km altitude before burning up.