How was space exploration affected by cooperation between the US and Russia?

Space cooperation between the USSR and USA was non-existent between 1958 and 1969 as both nations competed to become the first country to place a man on the moon.

The first example of cooperation was during the Apollo 11 mission in July 1969. Apollo 11 was in Lunar orbit attempting the first manned landing on the moon while the unmanned Soviet probe Luna 15 was attempting its own landing. It was designed to steal attention from Apollo 11 by robotically returning the first moon rocks to Earth before the Americans, but the probe lost control and crashed mere hours after Neil Armstrong and Buzz Aldrin took their first steps in the Sea of Tranquility. Surprisingly, the USSR notified NASA that Luna 15 would not interfere with Apollo 11 and was not close enough to the US spacecraft to risk a collision.

The Apollo-Soyuz Test Project of 1975 was the first example of real cooperation when surplus Apollo hardware was utilised to enable a manned docking in orbit between what has unofficially been dubbed 'Apollo 18' and Soyuz 19. American and USSR crew members visitied each others spacecraft in orbit and exchanged gifts through the open hatches of their vehicles before undocking and returning separately to Earth.

No further cooperation took place in the time of the USSR, but since the collapse of communism Russia and the US have exchanged crew members and cooperated in the building and upkeep of the International Space Station. Since the retirement of the Space Shuttle in 2011, US astronauts rely on Russian Soyuz craft to get them into orbit.