The Pioneer Venus Multiprobe, also known as Pioneer Venus 2 or Pioneer 13, was a spacecraft launched in 1978 to explore Venus as part of NASA's Pioneer program. This part of the program included a spacecraft bus which was launched from Earth. The bus carried one large and three smaller probes, which, after separating, each penetrated the Venusian atmosphere at a different location, returning data as they descended into the planet's thick atmosphere. The entries occurred on December 9, 1978. There was also an orbiter launched in 1978, part of the overall Pioneer Venus project along with this entry probe mission. Whereas the probes entered the atmosphere in 1978, the Pioneer Venus Orbiter would stay in orbit throughout the 1980s and the early 1990s.

Wikipedia: https://en.wikipedia.org/wiki/Pioneer_Venus_Multiprobe. Related NASA reference: https://science.nasa.gov/mission/pioneer-venus-2/. Description adapted from Wikipedia contributors (CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0/).