Apollo-Soyuz Test Project

On July 17, 1975, an Apollo command module docked with a Soviet Soyuz spacecraft 140 miles above the Elbe River, and Tom Stafford shook hands with Alexei Leonov through the open hatch. The Apollo-Soyuz Test Project was détente made visible — two Cold War rivals engineering a common docking system so their spacecraft could physically connect.

The crews spent two days conducting joint experiments and exchanging gifts, ceremonies, and meals. The androgynous docking adapter developed for the mission pioneered the international docking standards used today, and the working relationships formed carried forward to the Shuttle-Mir program and ultimately the International Space Station partnership.