A few close calls notwithstanding, the Cold War remained cold, without escalation to full-out warfare, on the principle of Mutually Assured Destruction (appropriately acronymed MAD). Both sides had radars capable of detecting enemy missiles in flight in time to launch a retaliatory strike of their own. In other words, any attack would likely wipe out both sides. Of course that didn’t stop the the U.S. and Russia from competing to take advantage of the radar’s supposed blind spots and gain first-strike advantage – by putting missiles in space.

On this day, January 27, in 1967, the long-titled Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies was signed by the governments of the Soviet Union, USA and UK.

The Outer Space Treaty, as it was informally called, forbade the placement of nuclear weapons of any kind in orbit, either independent or attached to any satellite. It also specifically forbade the militarization of the moon, designating it “a common heritage of mankind,” and open for all. It stopped short of a full demilitarization of space, however, allowing the placement of conventional (non-nuclear) weapons in orbit.