Soyuz 4 was a Soviet space mission launched on January 14, 1969. It was part of the Soyuz program and aimed to test the capabilities of the spacecraft in orbit. The mission lasted for 4 days, during which the crew conducted various scientific experiments and systems checks. The spacecraft was piloted by cosmonauts Viktor Patsayev and Valentin Lebedev. Notably, Soyuz 4 successfully docked with Soyuz 5, marking the first time two crewed spacecraft docked in space. This achievement paved the way for future missions and advancements in space exploration.