The first international partnership in space was the Apollo-Soyuz Test Project. An American Apollo spacecraft docked with the Russian Soyuz in order to test interoperability with rendezvous and docking systems. Additionally, one of the experiments conducted was a data relay demonstration with the ATS-6 mission and the Apollo station in Madrid, Spain. This experiment demonstrated over 50 percent communications coverage with a single relay. This experiment further concluded that the creation of the Tracking and Data Relay Satellites (TDRS) was the route for the future of space communications, but also opened the door for future collaborations like the International Space Station.
› Apollo Soyuz – A Pioneering Partnership› SCaN History of the 1970’s