A short history of planetary exploration

Arguably, space exploration began when Man first looked up at the night skies and noticed the constellations and those steady points of light that were first described as "wandering stars" and are now what we know to be planets.

The advent of telescopes meant that the heavens could be explored but it was not until the launch of Sputnik 1 (link opens in a new window) in 1957 that the space age could truly be said to have begun. This was closely followed by the launch of the first US satellite, Explorer III (link opens in a new window), in 1958 and the Ranger (link opens in a new window) and Surveyor (link opens in a new window) missions in the 1960s culminating in the landing on the Moon by Apollo 11 (link opens in a new window) in 1969.

In the meantime, the Russians had sent a series of robotic spacecraft in their Luna (link opens in a new window) and Zond (link opens in a new window) series to the Moon and in 1970 Luna 16 returned samples of moonrock to Earth followed by Luna 20 in 1972 and Luna 24 in 1976. These created a precedent for robotic planetary sample return missions, one that has still not been matched.

Although the Apollo missions visited the Moon six times, returning a total of 382 kilograms of lunar material, in the last decade or so the Moon has only been visited three times: by the spacecraft Clementine (link opens in a new window) in 1994, Lunar Prospector (link opens in a new window) in 1998 and Smart-1 (link opens in a new window), a European Space Agency (ESA) mission, in 2005.

In the 1960s, other interplanetary spacecraft travelled further afield with the launch of the Mariner (link opens in a new window) series of flybys of Venus, Mars and Mercury and the Pioneer (link opens in a new window) series, the first of which investigated the solar environment. Of the Venera (link opens in a new window) series launched by the Russians, Venera 7 landed on Venus in 1970 and was the first successful landing of a spacecraft on another planet. In the early 1970s, Pioneers 10 and 11 performed flybys of Jupiter and Saturn.  Venera 9 returned the first images of Venus' surface in 1975. 

In 1976 the US Viking (link opens in a new window) landers touched down on the surface of Mars, carrying out experiments to search for evidence of life. 1977 saw the launch of Voyagers 1 and 2 (link opens in a new window) which performed flybys of Jupiter and Saturn and, in the case of Voyager 2, Uranus and Neptune. Both spacecraft are still transmitting data from the edge of the Solar System and are the most distant man-made objects known. 

In the early 1980s Japan and Europe became Solar System-roving nations with flyby missions to comets and since then have successfully launched a range of spacecraft on missions to the Sun (Ulysses (link opens in a new window), Yohkoh (link opens in a new window), SOHO (link opens in a new window), Hinode (link opens in a new window)) and Mars (Mars Express (link opens in a new window)). From 1992-1994 the US-funded Magellan (link opens in a new window) mission mapped almost all of Venus' surface. 1997 saw the launch of the hugely successful joint US/ESA Cassini-Huygens (link opens in a new window) mission in which the Huygens probe successfully landed on Saturn's moon Titan in 2005, transmitting images during its descent and after landing.  

Over the last ten years a series of spacecraft have been launched to visit Mars and currently the Mars Exploration rovers Spirit and Opportunity (link opens in a new window) are actively transmitting data from the planet's surface while Mars Global Surveyor (link opens in a new window) (no longer active), 2001 Mars Odyssey (link opens in a new window), Mars Reconnaissance Orbiter (link opens in a new window) and ESA's Mars Express  (link opens in a new window)all orbit above. Finally, the US New Horizons (link opens in a new window) and MESSENGER (link opens in a new window) missions are on their way to Pluto and Mercury respectively.