Oct. 4, 1957
Sputnik 1 was the first artificial Earth satellite. It was a 58 cm diameter polished metal sphere, with four external radio antennae to broadcast radio pulses. The Soviet Union launched it into an elliptical low Earth orbit on October 4, 1957. It was visible all around the Earth and its radio pulses detectable.
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Sept. 12, 1959
Luna 2 (E-1A series) was the first spacecraft to reach the surface of the Moon and thus the first manmade object to land on another celestial body. On September 14 of 1959, it successfully impacted with the lunar surface east of Mare Imbrium near the craters Aristides, Archimedes, and Autolycus.
April 12, 1961
Vostok 1 was the first spaceflight in the Vostok program and the first human spaceflight in history. The flight took Yuri Gagarin, a cosmonaut from the Soviet Union, into space. The flight marked the first time that a human entered outer space, as well as the first orbital flight of a manned vehicle.
March 18, 1965
Voskhod 2 was a Soviet manned space mission in March 1965. It established another milestone in space exploration when Alexey Leonov became the first person to leave the spacecraft in a specialized spacesuit to conduct a 12 minute "spacewalk".
July 21, 1969
Apollo 11 was the spaceflight that landed the first humans on the Moon, Americans Neil Armstrong and Buzz Aldrin, on July 20, 1969. Armstrong became the first to step onto the lunar surface six hours later on July 21.
April 12, 1981
STS-1 (space transportation system) was the first orbital flight of NASA's Space Shuttle program. The first orbiter, Space Shuttle Columbia, launched on 12 April 1981 and returned to Earth on 14 April, having orbited the Earth 37 times during its 54.5-hour mission.
