The 1957 launch of Sputnik 1, the first Earth-orbiting satellite, sparked decades of competition in space between the United States and the Soviet Union.
Whatever the motivation, missions such as Apollo 11, Venera 9, and Cassini-Huygens have helped mankind develop an ever-widening knowledge of the Solar System and beyond.
With the end of the Cold War, competition in space exploration has increasingly given way to international collaboration.
Photo: An Apollo 16 astronaut with the lunar rover (NASA)
The United States lands astronauts on the Moon.
Astronauts visit a robotic probe on the Moon.
Astronauts narrowly survive an explosion on the way to the Moon.
Astronauts climb a crater and hit golf balls.
Astronauts drive a lunar rover on the Moon for the first time.
Astronauts explore the Moon's Descartes region.
Harrison Schmitt becomes the only scientist to walk on the Moon.
Astronauts orbit the Moon for the first time.
America lands a man on the Moon.
An unmanned probe explores Saturn and its moons.
The unmanned probe to Jupiter sees a comet crash.
Astronauts and engineers prepare for manned Moon landings.
International crews live and work in space.
The Soviets crash a probe into the Moon.
The Soviets make the first soft landing on the Moon.
Soviet Moon probes achieve a number of firsts.
A NASA probe maps cloudy Venus.
The first two-planet mission reaches Mercury.
The first Mars flyby returns close-up photos.
A two-probe mission flies by Mars in 1969.
The first Mars orbiter gets a good look at the surface.
Unmanned probes explore the inner Solar System.
Two hardy robotic vehicles crawl across Mars.
A pioneering Mars rover bounces down.
An eagle eyed probe surveys Mars.
After 30 years, there is another mission to Mercury.
Two US probes make discoveries about Venus.
Trailblazing missions travel across the Solar System.
A string of lunar crashes helps the Moon landing planners.
Crews on the first US space station study the Sun.
Look back on the world's first reusable spacecraft.
A small Soviet satellite starts the Space Age.
Unmanned probes land on the Moon to study potential landing sites.
A European probe flies over the Sun's poles.
Soviet probes battle extreme conditions on Venus.
A European probe finds evidence of past water on Venus.
Two probes search for Martian life.
The Earth's ambassador to the stars is far from home.
A voyage of discovery that started in the 1970s continues today.
Two probes visit the outer planets on their long journey.