Konstantin Eduardovic Tsiolkovsky, a Russian scientist called 'the father of space travel', formulates the Rocket Equation, which shows that the greater the velocity of ejected gases, and the greater the ratio of their mass at ignition to their mass at burn out, the higher the rocket can fly. This equation is still used in the design of modern rockets.

The first flight of a liquid fuelled rocket. Robert Hutchins Goddard designs, builds and launches a liquid-powered rocket from a snow-covered field at his Aunt Effie's farm in Massachusetts, USA. The rocket flies for 46 metres (50 yards).

In September, Adolf Hitler launches the V2 rocket flying bombs against targets in Britain. After he loses the war in 1945, many of Germany's best rocket scientists are recruited by the USA.

In October, the Soviet Union launches Sputnik 1, the first artificial satellite. In November, Sputnik 2 carries Laika, a dog, the first living creature in space. Laika dies a week later because the Russians are unable to return her to earth. Meanwhile, the USA develops the first intercontinental ballistic missile.

The Americans, lagging behind in the Space Race, launch Explorer 1 into orbit. This is followed by several unsuccessful attempts to send an unmanned probe to the moon. Gordo, a squirrel monkey, is launched into space on Jupiter AM-13, a US mission. He dies on re-entry.

The Russians launch Lunar 1 Probe, which fails to hit the moon. Lunar 2, launched in September, lands on the moon and becomes the first probe to reach a celestial object. Lunar 3 is also successful, bringing back the first pictures of the dark side of the moon.

The Soviet Union launches Marsnik 1, a Mars probe, but it fails to leave Earth. This is the first of five Russian attempts to launch a Mars probe between 1960 and 1962 - all unsuccessful.

The Cold War hots up. Ham, a chimp, is launched into space on Mercury Redstone 2. He returns to Earth unharmed. But Ham's trip is overshadowed by the Soviet launch of the first ever manned vehicle, Vostok 1, on April 12. Yuri Gagarin becomes the first man in space. Three weeks later, the Americans launch a Mercury spacecraft, which carries Alan Shepard, portrayed in Tom Wolfe's book, The Right Stuff. The Russians launch a mission to Venus - it fails.

1962: The Americans launch a Venus mission - it fails.

1963: The Soviet Union's Valentina Tereshkova becomes the first woman in space.

The USA launches Mariner 3, with the objective of completing a Mars flyby, but it fails. Mariner 4, launched a few weeks later, comes within 9,912km (6,155 miles) of Mars, taking 22 photographs. The Soviets launch the Voskhod. Cosmonaut Aleksei Leonov completes the first spacewalk.

On July 20, Apollo 11 lands on the Sea of Tranquility on the moon. Neil Armstrong becomes the first man to moonwalk. His first words, 'One small step for man, one giant leap for mankind', are broadcast around the world. Along with astronaut Buzz Aldrin, he spends two hours on the lunar surface, collecting samples and setting up observation equipment. Mariner 6 approaches within 3,330km (2,067 miles) of Mars.

A further mission to the moon goes disastrously wrong when the main oxygen storage tank on Apollo 13 blows up, severely limiting the amount of oxygen available for the three astronauts on board. Without light and heat, the crew manages to return to earth. A Soviet craft, Venera 7, completes the first soft landing on Venus. Venera measures the temperature at the Venusian surface and finds it is 470C.

Mars 2, a Soviet craft designed to land on Mars, crashes on the surface. A week later, Mars 3 lands on the planet, returning 20 seconds of data. USA fails to launch Mariner 8.

The Americans launch Skylab, a new departure in space exploration - it is designed as a place for people to live and work in space.

The Soviets and Americans embark on their first major project together, as the US Apollo spacecraft docks with the USSR's Soyuz while in space. The two crews visit each other's craft and eat together. Viking probes 1 and 2 are launched and land on the surface of Mars. No living organisms are found but Viking 2 brings back more than 55,000 images of the Martian surface.

The US Space Shuttle Columbia is launched for the first time on a two-day mission.

1986: The US Space Shuttle Challenger explodes one minute and 13 seconds after lift-off, killing seven crew. The Soviets launch Mir, the space station, into orbit.

1988: The US recommences manned space flight.

1992: Mars Observer, a $800 million-probe, is launched. Three days before it reaches Mars, it is lost in space.

1995: A US space shuttle docks with the Russian's Mir Space Station for the first time.

Mars Pathfinder is launched. Pathfinder carries a rover - a small, robotic field geologist - which becomes the first vehicle to move across the Martian surface. The pictures it sends back thrill the scientific community, but, after 90 days, Pathfinder breaks down. The Americans also launch Mars Global Surveyor, which orbits Mars.

A Russian proton rocket places the Zarya module - the first part of the International Space Station (ISS) in orbit. Japan launches Nozomi (Planet-B), a Mars orbiter, on 3 July.

Global Surveyor pictures reveal the possibility that water may have been on the surface of Mars 'recently' - within the past million years.

The ISS's first permanent crew arrives, and the last crew of the Mir station departs, leaving the Russian station unmanned for the first time in almost 15 years. Both the USA and Russia make plans for sending manned flights to Mars.

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