Guns. In Space. Need we say more?
That was the idea the Soviet Union had to defend their Almaz space stations, which were their secret manned spy outposts. See, when the three Almaz missions launched in the 1970s, the Soviets had long worried that the Americans were developing anti-satellite weapons. They needed something for self-defense.
Enter the R-23M Kartech, the space version of a gun originally developed to take out fighter jets from the back of Soviet bombers. It could fire 950 to 5,000 14.5-millimeter rounds per minute at a velocity of 1,500 miles per hour (2,414 kilometers per hour), hitting targets as far as 2 miles (3.2 kilometers) away. In defiance of international law, which prohibits the militarization of space, the gun was secretly mounted on the Almaz 2 space station, which launched in 1974 [source: Atherton].
Only after the fall of the Soviet Union in 1991 did the world discover that they actually had test fired the R-23M — in space — on Jan. 25, 1975. For safety reasons Soviet ground control waited until the last crew departed the station and, while simultaneously firing the jet thrusters to counteract recoil, they unloaded a few bursts of maybe 20 shells in total [source: Zak].