First docking between two crewed spacecraft

The first docking between two crewed spacecraft occurred during the missions of the USSR's Soyuz 4 and Soyuz 5. This event marked a pivotal advancement in human spaceflight, demonstrating the capability of spacecraft to connect in orbit and facilitate crew exchanges. The Soyuz 4 spacecraft was launched with a crew of two, while Soyuz 5 carried three cosmonauts. After successfully docking in Earth orbit, one cosmonaut from Soyuz 5 transferred to Soyuz 4, making it the first instance of a crew exchange in space. This docking maneuver not only showcased the technical prowess of the Soviet space program but also laid the groundwork for future missions that would involve more complex operations in space, including the assembly of larger space stations and international collaborations in human space exploration. The successful execution of this docking operation was a significant step forward in the development of space travel, enhancing the understanding of orbital mechanics and the logistics of crewed missions.