The U.S. space shuttle "Atlantis" and four crew members blasted off on July 8 for the shuttle program's final 12-day mission in space.
Since the maiden voyage of the "Columbia" in 1981, the shuttle program has served as a powerful symbol of U.S. superiority in space.
NASA's Space Shuttle Program retires having amassed a significant list of achievements. The five shuttles, developed and maintained at a cost of nearly $210 billion, are the fastest winged vehicles ever to have flown. They account for half the mass of all payloads launched worldwide since Sputnik in 1957. More than 350 crew members from 16 countries -- 49 of them women -- have flown on shuttle missions, traveling more than 800 million kilometers around the globe. The shuttles even played a diplomatic role, fostering international cooperation with visits to the Russian space station "Mir" and later, the International Space Station.
There were dark days as well. The 25th shuttle mission, broadcast live on television to millions of viewers on January 28, 1986, ended in tragedy when the "Challenger" broke up 73 seconds into its flight. Seven crew members died, including the first teacher in space, carefully selected volunteer Christa McAuliffe. In February 2003, the "Columbia" and its crew of seven were killed near the end of their mission while reentering Earth's atmosphere.
NASA spokesman Kyle Herring says that even though the shuttle has severe limitations, its legacy as a reusable spacecraft is secure.
"The shuttle has proven not only in the assembly of the [International] Space Station to be a versatile vehicle, but it's obviously been used for quite a number of other missions throughout its history," Herring says. "So the legacy of the shuttle will be that it's a very versatile vehicle."
WATCH: Thirty years of the Space Shuttle Program (video by AP)
Wayne Hale, a retired manager of NASA's Space Shuttle Program, says the shuttle project came on the heels of NASA Apollo program, which put 12 men on the Moon in six separate missions between 1969 and 1972.
He has reservations about seeing the end of the shuttle era.
"My biggest regret is that we haven't already built the successor to the shuttle," Hale says. "The failure of the United States or the world to build a successor that would be safer, fly more efficiently, is a really sad thing. We do have a plan to build a successor vehicle, but there is going to be a gap now a few years before we have that built between the time we retire the shuttle and the new vehicle is ready to go flying."
In the aftermath of the "Columbia" disaster, U.S. President George W. Bush in 2004 announced that the ISS would be completed and the space-shuttle program then ended. A new program, dubbed "Constellation," was announced with the intention of carrying astronauts to the moon, and eventually to Mars.
A panel conducted under President Barack Obama, however, concluded that the Constellation program was not feasible and terminated it. The administration in 2010 announced a policy shift toward the use of private-sector rockets and the government's development of heavy-lift rockets.
Hale says this means that, for now, the United States will have to rely solely on Russian carriers for transporting its astronauts to the Space Station.
"It's troubling because we have the space station to support -- we would like to be able to send people (to the ISS) all the time," Hale says. "Right now, the Russian Federation's Soyuz is going to be our mainstay for that time period. So we go from having two ways to get to the space station to one way to get to the space station. That makes you a little bit nervous."
Workers make their way off the Rotating Service Structure at the Kennedy Space Center in Cape Canaveral, Florida, on July 7.
This year, NASA awarded approximately $270 million to four commercial companies to develop commercial rockets and spacecraft capable of transporting humans and cargo to space. The hope is that the Russian monopoly on manned space flight will come to an end when the United States decides on its new spacecraft in 2016 -- by which time it is estimated that NASA will be paying Russia $63 million each to send astronauts into space aboard a Soyuz rocket.
By then, the "Discovery," "Endeavour," and "Atlantis" will be well into their new, more earthly missions -- as exhibits at space museums in Los Angeles, New York, and Washington.