This is a big day for NASA and space buffs around the world, who are celebrating two major anniversaries.
Today marks the 50th anniversary of the first human space flight, as well as the 30th anniversary of NASA's first space shuttle launch.
The latter anniversary is a somewhat bittersweet milestone for the U.S. space agency, which will soon retire its Space Shuttle fleet and transition into a new era.
On April 12, 1961, Russian cosmonaut Yuri Gagarin , the son of a Moscow carpenter, made history with a 108-minute orbital flight around the Earth to become the first human in space.
Gagarin's spacecraft, dubbed Vostok 1, circled Earth at a speed of about 17,000 miles per hour and reached a height of about 203 miles above Earth.
Russia's launch of the first human into space marked the beginning of the space race. A month after Gagarin's flight, NASA astronaut Alan Shepard became the first American in space.
"Yuri's first flight really did spur NASA into action, getting our astronauts into space and to the moon," said Daniel Lockney, a program specialist with NASA. "It was an exciting time."
The U.S. hit a major milestone when NASA launched Columbia , the first space shuttle craft, on April 12, 1981. The fleet of reusable space vehicles, which includes Challenger, Discovery, Atlantis and Endeavour, are designed to go into space and then return to Earth like a giant glider. The program ushered in a whole new era in space travel.
NASA noted that Columbia's original liftoff marked the first time in history a new spacecraft was launched with a crew aboard on its maiden voyage .
The NASA space shuttle craft , each of which is longer than three school buses, have collectively flown a total of 513.7 million miles, according to NASA.
Thanks largely to the efforts of the various space shuttles, NASA and its international teammates were able to build out the International Space Station .
The space shuttle Discovery deployed the Hubble Space Telescope in 1990 and the shuttle team since lifted off for five different servicing missions to maintain and upgrade the telescope's scientific instruments and operational systems.
Along with the many accomplishments, NASA has had its share of tragedy and heartbreak with the space shuttles as well.
On Jan. 28, 1986, the space shuttle Challenger broke apart in the sky over Florida just 73 seconds after it lifted off. The Challenger's seven crew members were killed.
The accident was caused by a faulty O-ring seal in the shuttle's right solid rocket booster. The failed seal eventually led to the structural failure of an external fuel tank, which then ripped the rest of Challenger apart.
And then on Feb. 1, 2003, the space shuttle Columbia disintegrated during re-entry into the Earth's atmosphere, killing all seven crew members. NASA reported that the accident was caused because of a piece of foam the size of a briefcase broke off from the shuttle's external fuel tank, striking the left wing of the craft and damaging the shuttle's thermal protection system. The damaged system was unable to protect the shuttle from the intense heat the shuttle needs to endure during re-entry.
Today, all but two of NASA's shuttle fleet have flown their final missions.
Endeavour is set for its final launch on April 29. The crew will take the shuttle aloft for a 14-day mission to the space station to deliver supplies and spare parts, including two S-band communication antennas, robotic parts and a meteor debris shield.
Atlantis is scheduled to make lift off on June 28 for the final shuttle voyage. After the Atlantis mission, the shuttle fleet will be officially retired.
The space shuttle made its final trip into space in February.
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin , or subscribe to Sharon's RSS feed . Her e-mail address is firstname.lastname@example.org .
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