Launched in November 1965, Venera 3 lost communication before entering the Venusian atmosphere due to a failure in its radio system, so it returned no data about the planet it struck. Even so, its impact on Venus's surface marked the first time an object built by humans had reached the surface of another planet, a milestone in the Soviet Union's aggressive planetary exploration program.
The Soviet space program in the 1960s ran an almost assembly-line approach to Venus, launching probe after probe in a dogged campaign to reach a planet whose thick, scorching atmosphere destroyed one spacecraft after another. Venera 3 launched on November 16, 1965, one of a pair of sister probes, and spent nearly four months in transit toward Venus.
Somewhere along that journey its radio system failed silently, and mission controllers in Moscow lost contact before the spacecraft ever reached its target. Venera 3 continued on its trajectory regardless, and on March 1, 1966 (with confirmation and announcement following in the following days), it struck the Venusian surface, becoming the first human-made object to make contact with another planet, though it returned no measurements, no photographs, nothing but the bare fact of arrival.
Soviet engineers treated the mission as only a partial success, since the entire point of planetary probes was data, not mere impact. But the achievement, however hollow scientifically, was real: a machine built on Earth had crossed tens of millions of miles of space and touched down, however violently, on the surface of a wholly alien world, a full three years before Apollo 11 would put human footprints on the Moon.