Which NASA mission dropped four probes into Venus's atmosphere in 1978?

The Pioneer Venus Multiprobe was the NASA mission that dropped four probes into Venus’s atmosphere in 1978. Also called Pioneer Venus 2 or Pioneer 13, it carried one large probe and three smaller probes toward Venus.

The spacecraft launched on August 8, 1978, and the four probes entered Venus’s atmosphere on December 9. They approached different locations, measuring temperature, pressure, atmospheric composition, cloud particles, radiation, and wind conditions during descent. A separate bus also gathered measurements in the upper atmosphere before burning up.

The mission was part of the broader Pioneer Venus project, which included the Pioneer Venus Orbiter. The orbiter studied Venus from space, while the Multiprobe directly sampled the atmosphere. This distinction causes a common mix-up: “Pioneer Venus” refers to a program with multiple spacecraft, whereas the four atmospheric probes specifically belonged to the Multiprobe mission.

The probes confirmed Venus’s extreme surface environment and found powerful winds in the cloud layers. The Day Probe even continued transmitting for 67 minutes after reaching the surface, an exceptional achievement under Venus’s crushing pressure and heat.