In 1975, Soviet Union sent a cannon to space and tested it from Salyut 3 station, just six months before US and Soviet astronauts met in orbit for the Apollo-Soyuz mission during the Cold War

In January 1975, the Soviet Union fired a 23mm cannon from its Salyut 3 space station, testing a weapon that had been designed to protect the spacecraft from a possible attack in orbit. The test came just months before American astronauts and Soviet cosmonauts would meet in space for the historic Apollo-Soyuz mission.

Salyut 3 belonged to the Soviet Almaz programme, a military space station project that the Soviet Union presented publicly as part of the Salyut series. The station carried reconnaissance equipment as well as defensive systems, including the rapid-fire cannon. The Soviet Union kept much of the programme secret during the Cold War.