Nowadays, the space exploration of human beings has made great achievements that speed up our conquering process to other planets. However, in order to get these successes, we cannot forget key events happening during nearly two centuries as well as scientists who lost their lives to discover the new lands.
Below is the list of top ten important events in the history of space exploration.
4 October 1957: Soviet Union launched the first Earth-orbiting artificial satellite called Sputnik I to initiate the space race. Sputnik\'s radio signals continued for 22 days until the transmitter batteries run out.

The first Earth-orbiting artificial satellite Sputnik I
3 November 1957: The dog Laika was the first living creature to orbit the Earth by the satellite Sputnik II. However, she died a few hours after launch.

The dog Laika
12 April 1961: The space exploration’s history named Yuri Gagarin from Soviet Union as the first human in outer space and the first to orbit the Earth.

The Soviet cosmonaut, Yuri Gagarin
5 May 1961: Alan Shepard became the first American in space on a suborbital flight lasting 15 minutes and 28 seconds.

Twenty days after this achievement, President John F Kennedy pledged that America would send a man to moon before the end of the decade
24 December 1968: Astronaut William Anders successfully took a photograph of the Earth behind the moon\'s horizon during the Apollo 8 mission.

An image of the Earth behind the moon\'s horizon by William Anders
20 July 1969: Neil Amstrong and Edwin "Buzz" Aldrin set a new record when they were the first humans to walk on the moon.

They also fulfilled JFK\'s goal of reaching the moon by the end of the 1960s
28 January 1986: The explosion of space shuttle Challenger after 73-second take-off became a major catastrophe for NASA.

All seven crew-members are killed including teacher Sharon Christa McAuliffe and a civilian
28 April 2001: An American multimillionaire, Dennis Tito, became the first space tourist with 7 days, 22 hours and 4 minutes in space.

He also orbited the Earth 128 times
1 February 2003: Space Shuttle Columbia disintegrated over Texas during re-entry into the Earth\'s atmosphere after 16 days in space.

All seven crew-members were killed
21 June 2004: SpaceShipOne became the first privately manned craft to reach outer space and won the $10 million Ansari X PRIZE four months later by reaching an altitude of 100 kilometers.

After the successes of SpaceShipOne, a larger and more powerful space plane called SpaceShipTwo is planned to carry fare-paying passengers into space by 2011
Related links:
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Important Events in Space Exploration