In perhaps the most iconic image from the flight, Astronaut Deke Slayton and cosmonaut Aleksey Leonov are seen together in the Soyuz spacecraft.

Both men were already icons in the world of spaceflight. Slayton was one of NASA's original astronauts who went on to head the astronaut office, while Leonov had made history as the first person to conduct a spacewalk in 1965.

Credit: NASA