Notable events in the history of human space exploration:
Oct. 4, 1957
First artificial satellite, Sputnik I, is launched by Soviet Union.
April 12, 1961
Soviet cosmonaut Yuri Gagarin completes the first manned space flight, orbiting the Earth in 108 minutes.
May 5, 1961
U.S. launches first American astronaut, Alan Shepard Jr., into space, on a 15-minute, 22-second suborbital flight.
May 25, 1961
President John F. Kennedy declares the American space objective to put a man on the moon and return him safely by the end of the decade.
Feb. 20, 1962
John Glenn becomes first American to orbit Earth, completing three orbits.
June 16-19, 1963
Cosmonaut Valentina Tereshkova, the first woman in space, completes 48 orbits.
March 18, 1965
Cosmonaut Aleksei Leonov takes man's first space walk.
Jan. 27, 1967
Astronauts Gus Grissom, Edward White and Roger Chaffee die when a fire sweeps the Apollo I command module during a ground test at Kennedy Space Center.
Dec. 21, 1968
First manned spacecraft to orbit moon, Apollo 8, comes within 70 miles of lunar surface.
July 20, 1969
Man walks on the moon. Neil Armstrong and Edwin "Buzz" Aldrin of Apollo 11 spend 21 1/2 hours on the moon, 2 1/2 of those outside the capsule.
Dec. 7-19, 1972
Apollo 17 mission that includes the longest and last stay of man on the moon — 74 hours, 59 minutes — by astronauts Eugene Cernan and Harrison Schmitt.
July 17-19, 1975
U.S. astronauts and Soviet cosmonauts participate in Apollo-Soyuz Test Project, docking together in space for two days.
April 12, 1981
Shuttle Columbia becomes first winged spaceship to orbit Earth and return to airport landing.
June 18, 1983
Sally Ride becomes first American woman in space.
Feb. 7, 1984
Astronaut Bruce McCandless performs man's first untethered space walk with a Manned Maneuvering Unit off the Challenger space shuttle.
Jan. 28, 1986
Challenger explodes 73 seconds after launch, killing crew of seven.
Dec. 21, 1988
Cosmonauts Vladimir Titov and Musa Manarov return to Earth from Soviet space station Mir after man's longest space flight — 365 days, 22 hours, 39 minutes.
June 29, 1995
Atlantis docks with Mir in first shuttle-station hookup.
Sept. 26, 1996
Shannon Lucid returns to Earth after 188-day Mir mission, a U.S. space endurance record and a world record for women.
May 29, 1999
Discovery becomes first shuttle to dock with the International Space Station.
Feb. 1, 2003
Columbia breaks apart over Texas, 16 minutes before it was supposed to land in Florida.
July 21, 2011
Final space shuttle mission ends when Atlantis arrives at Kennedy Space Center.