On display at the Kansas Cosmosphere in Hutchinson, Kansas — it’s a snapshot of a breather in the cold war (on the left, a mockup Apollo spacecraft; on the right, a Soyuz mockup):
Conducted in 1975, the Apollo-Soyuz Test Project (ASTP) was an opportunity for the Soviet and American human space programs to experiment with working together. In retrospect, it makes sense that the respective technical communities (despite fairly divergent philosophies w.r.t. engineering) worked together more easily than did the two countries’ politicians.
Still, the joint mission wasn’t possible until U.S./U.S.S.R. tensions started to ease in the early 1970s as the Vietnam War began to wind down. The two nations committed to the mission in 1972, with the two spacecraft launching 7-1/2 hours apart on 15 July, 1975. They docked on 17 July, spent 44 hours together, then the two spacecraft spent several days conducting separate investigations in low Earth orbit.
The ASTP mission was considered a great success by both sides, and set a number of milestones. Along with being the first joint mission for the U.S. and U.S.S.R., ASTP was the last flight of an Apollo spacecraft. It would also be the last time American and Russian craft would dock in space until the STS-71 mission saw the space shuttle Atlantis dock with the Mir space station in 1995.