From the first human journeys to the Moon to robotic spacecraft exploring distant planets, space missions have transformed our understanding of the Solar System. Some spacecraft have landed on other worlds, while others have flown past planets, studied their moons and continued into interstellar space. Explore nine mission guides covering the achievements, discoveries and challenges of planetary exploration.
The Moon and Human Exploration
Apollo Missions
Key missions: Apollo 8 (1968) · Apollo 11 (1969) · Apollo 17 (1972)
NASA’s Apollo program achieved the first human Moon landing in 1969 and eventually placed 12 astronauts on the lunar surface. Its missions returned lunar samples and transformed our understanding of the Moon’s history.
Exploring the Inner Planets
Mercury Mission
Key missions: Mariner 10 (1974–75) · MESSENGER (2011–15) · BepiColombo (2018 launch)
Spacecraft have revealed Mercury’s heavily cratered surface, unusual magnetic field and surprisingly complex geological history.
Venus Missions
Key missions: Mariner 2 (1962) · Venera 7 (1970) · Magellan (1990–94)
Missions to Venus have investigated its dense atmosphere, photographed its hostile surface and mapped a landscape shaped by extensive volcanic activity.
Mars Missions
Key missions: Mariner 4 (1965) · Viking 1 & 2 (1976) · Spirit & Opportunity (2004) · Curiosity (2012) · Perseverance (2021)
From early flybys to robotic rovers, Mars exploration has uncovered evidence of ancient water and investigated whether the planet once offered conditions suitable for life.
Exploring the Giant Planets
Jupiter Missions
Key missions: Pioneer 10 (1973) · Voyager 1 & 2 (1979) · Galileo (1995–2003) · Juno (2016)
Spacecraft have revealed Jupiter’s turbulent atmosphere, powerful magnetic field and extraordinary moons, including volcanic Io and icy Europa.
Saturn Missions
Key missions: Pioneer 11 (1979) · Voyager 1 & 2 (1980–81) · Cassini-Huygens (2004–17)
Missions to Saturn have transformed our understanding of its magnificent rings, complex atmosphere and remarkable moons, particularly Titan and Enceladus.
Exploring the Outer Solar System and Beyond
Pluto Missions
Key encounters: Pluto (2015) · Arrokoth (2019)
New Horizons delivered humanity’s first close-up images of Pluto, revealing icy mountains, vast plains and a surprisingly varied world. It later explored Arrokoth in the Kuiper Belt.
Exploring the Outer Solar System and Beyond
Pluto Mission
Key encounters: Pluto (2015) · Arrokoth (2019)
New Horizons delivered humanity’s first close-up images of Pluto, revealing icy mountains, vast plains and a surprisingly varied world. It later explored Arrokoth in the Kuiper Belt.
Voyager 1 — Interstellar Space
Key milestones: Jupiter (1979) · Saturn (1980) · Interstellar space (2012)
Voyager 1 explored Jupiter and Saturn before becoming the first spacecraft to enter interstellar space in 2012.
Voyager 2 — The Four Giant Planets
Key encounters: Jupiter (1979) · Saturn (1981) · Uranus (1986) · Neptune (1989)
Voyager 2 remains the only spacecraft to have visited all four giant planets, revealing new moons, unusual magnetic fields and active geysers on Triton. In 2018, it followed Voyager 1 into interstellar space.