3. November 12, 1981: STS-2, Columbia With its second space flight, Space Shuttle Columbia cemented its position as the first reusable, manned orbiter in the world to return to space. The mission wasn't just for claiming a title, however; Columbia brought the Canadian-built Remote Manipulator System robotic arm with it (pictured above), also known as the "Canadarm," which would play a crucial role in future missions and even on the International Space Station. The two stars you see on the mission badge above represent Columbia's two flights, and this second flight also saw far less damage to the heat shield, and less complications with the shuttle's systems. [Read more]

4. November 11, 1982: STS-5, Columbia The fifth shuttle mission was also Columbia's fifth flight, its last one before letting another orbiter have the stage (up next in this gallery). STS-5 was NASA's first true operational mission, carrying a crew of four — a commander, pilot and two mission specialists, who perform special tasks unique to each spaceflight — and two commercial satellites to be deployed in orbit. A space walk was also scheduled, though it was canceled due to a "malfunction of the space suit." On the mission badge you can see the two satellites ("blasting off" using their Payload Assist Modules), as well as a large, five-pointed blue star, representing Columbia's fifth launch. [Read more]

5. April 4, 1983: STS-6, Challenger Space Shuttle Challenger's first mission was a big one: it was the first test of NASA's Extravehicular Mobility Unit — what we think of as a space suit — and, in turn, the first space walk for the shuttle program, which lasted over four hours. STS-6 also deployed the first Tracking and Data Relay Satellite for NASA, eight of which form NASA's ground-to-space communications system today. In the badge: six white stars to represent the sixth Space Shuttle mission, with the TDRS shown above Challenger's bay. [Read more]

2. April 12, 1981: STS-1, Columbia The first Space Transportation System mission — the official name for NASA's shuttle program — saw Space Shuttle Columbia embark on a 54-hour mission during which it orbited the planet 37 times. Like the ALT tests before it, STS-1 involved only a commander and a pilot, and the purpose of the flight was to make sure Columbia's design made for a reusable, space-worthy craft, which would be the first of its kind in the world. The test flight did experience a few hitches, however, from damage to the heat shield causing excessive warming and melting, to the toilet suffering from "low urinal flow and a feces separation problem." Columbia's launch on April 12 comes 20 years after, to the day, that cosmonaut Yuri Gagarin became the first man in space. [Read more]

7. August 30, 1984: STS-41-D, Discovery The maiden voyage of Space Shuttle Discovery was actually supposed to occur two months early on June 26, but was aborted rather dramatically at takeoff minus four seconds to launch. It was the first abort for the shuttle program. The launch, two months later, saw Discovery go up for the first time with six crew members — including one woman and a commercially-sponsored employee from defunct aerospace company McDonnell Douglas — and a cargo hold full of satellites. The payload also included an extendable solar array (seen here), which was the largest structure every extended from a manned spacecraft and paved the way for solar applications in space. In the badge: 12 stars for the 12th mission; the HMS Discovery, the shuttle's namesake. [Read more]

8. October 3, 1985: STS-51-J, Atlantis The first launch of Space Shuttle Atlantis was also the second shuttle flight completely devoted to the Department of Defense. The DoD carried out several classified missions using the shuttles, many of which are still classified, though there are some pictures available such as this one of a DoD satellite in Atlantis's hold. STS-51-J launched two satellites for the Defense Satellite Communications System, which remains an important part of the U.S. military's communications network. Atlantis is one of two shuttles still operating. [Read more]

10. April 24, 1990: STS-31, Discovery Here should be a familiar face, so to speak: Space Shuttle Discovery uses the Canadarm to deploy everyone's favorite eagle-eyed orbiter, the Hubble Space Telescope. The Hubble Space Telescope is the first of four of what's known as NASA's Great Observatories, which are all super-strong, space-based telescopes. The remainder of STS-31 after the HST deployment went to carrying out experiments and shooting video with two IMAX cameras — which is why we have awesome space docs such as Destiny in Space. [Read more]

11. April 5 1991: STS-37, Atlantis The second of NASA's Great Observatories, the Compton Gamma Ray Observatory, is seen here behind Mission Specialist Jerry Ross. Ross and astronaut Jay Apt, a fellow mission specialist, performed the first space walks in six years, spending nearly 11 hours in the vacuum (broken into two separate space walks) after a problem with the CGRO's antenna hindered its deployment. Scary/fun fact: the glove of one astronaut during the space walk was punctured by a rod, though explosive decompression — luckily — didn't occur and the breach wasn't seen until after. [Read more]

13. Jun 27 1995, STS-71, Atlantis In 1993, two years after the collapse of the Soviet Union, America and the Russian Federation we know today announced a collaboration that would see astronauts and cosmonauts working together and involving Mir, Russia's since-deorbited space station, in the Space Shuttle program. To that end, Space Shuttle Atlantis, carrying five astronauts and two cosmonauts (and returning to Earth with two of the latter and an astronaut who had gone up aboard a Russian vessel), docked with Mir for five days to resupply the station and rotate the crew (pictured above). STS-71 also marked America's 100th manned space mission. [Read more]

14. November 19, 1996: STS-80, Columbia STS-80 was an odd mission for a lot of reasons. Not only was the launch delayed, but so was the landing due to bad weather. The two space walks planned were canceled after running into problems with the shuttle's airlock. Columbia also carried two satellites it was tasked with retrieving on the same mission, satellites which were gathering data in preparation for building the International Space Station. For all these reasons, STS-80 was the longest shuttle flight in history: Columbia stayed in orbit for over 17 days and orbited the planet 279 times. Mission Specialist Story Musgrave set a record two, being the only astronaut to ride into space on all five shuttles. [Read more]

15. December 4, 1998: STS-88, Endeavour What you see up above is the first module of what is now the International Space Station. The module, provided by the U.S., is known as Unity, and serves as the central hub for the station's various module connections. The Endeavour crew, which included Russian cosmonaut Sergei Krikalev, merged Unity with Zarya, a Russian cargo module already in orbit. A good majority of future space shuttle missions would involve the ISS in some way. [Read more]

16. February 1, 2003: STS-107, Columbia NASA and the U.S. space program had its collective noses bloodied once more with the second — and, hopefully, last — Space Shuttle program disaster. Like Challenger, all seven hands perished, though Columbia disintegrated while reentering the atmosphere, not at launch. On board was Ilan Ramon, the first Israeli astronaut. Up above is a hangar filled with the remnants that could be recovered of the shuttle. It was found that a piece of foam, dislodged at launch, knocked against the left wing, compromised the vessel's heat shield and caused it to break up upon reentry. [Read more]

17. July 25, 2005: STS-114, Discovery It took over two years for the U.S. space program to recover from the loss of Columbia. Discovery's ascent wasn't as triumphant as it could have been, either, as hard foam fell away from the shuttle's external fuel tank during launch and threatened to repeat 2003's disastrous reentry. The shuttle pulled through after some in-flight repairs, however, and it was a fitting success considering it was Discovery that flew the mission following the Challenger disaster. Still, STS-114 proved a rocky one for NASA, and the agency grounded its fleet for a year to carry out inspections. [Read more]

18. February 24, 2011: STS-133, Discovery Here we are, folks: the twilight years of NASA's shuttle program. STS-133 marked the last flight for Discovery, which, all told, completed 39 missions, docked with the International Space Station 13 times, with Mir once, and orbited the Earth a total of 5,830 times during the vessel's 365 days spent in space — that's right, a whole year's worth of time logged in orbit. Discovery's final voyage saw it take a variety of items to the Station, including Robonaut2 (pictured), a legless humanoid robot developed by NASA, designed to serve on the ISS alongside its human counterparts. [Read more]

20. June 28, 2011 (planned): STS-135, Atlantis After 25 years of service, 293 days in space, over 4,600 orbits and 32 missions, Space Shuttle Atlantis will launch for the last time and close out a chapter in the history of American spaceflight. Once it returns from its mission, Atlantis will join Endeavour as a museum showpiece, finding a home at NASA's Kennedy Space Center in Florida. With Atlantis retired, NASA will no longer have a shuttle in its service, though America's collaboration with Russia, Japan and other nations, and the push in the private sector for manned spaceflight, doesn't mean that the U.S. will be grounded just yet. Seen above: President Obama and his family inspecting the underbelly of Atlantis. [Read more]

1. August 12, 1977: ALT-12, Enterprise The Space Shuttle Enterprise was really only a shuttle in name. It wasn't equipped with liquid-fuel rocket engines, nor did it have a heat shield to see it through the atmosphere. Still, it was airworthy, and the Approach and Landing Tests (thus ALT) Enterprise completed paved the way for NASA's first true orbiter, Columbia. Enterprise is seen above performing its first free flight during ALT-12: it pushed away from the Boeing 747 Shuttle Carrier Aircraft, proved the design could fly within our atmosphere and landed just like future shuttles would be expected to. Its special tail cone — not a fixture on space-worthy orbiters — reduced Enterprise's drag while riding piggyback. The Enterprise flew four more times after ALT-12 and was retired after the testing phase wrapped up. [Read more]

12. May 7, 1992: STS-49, Endeavour The youngest shuttle in the fleet, Endeavour, embarked on a nine-day mission for its maiden voyage to capture and redeploy a satellite which failed to achieve its intended geosynchronous orbit. Up above you can see Intelsat VI being wrangled by three of the shuttle's crew. A first, planned space walk — or EVA — was followed by two unscheduled walks after capturing the satellite proved difficult. All told, Endeavour's crew performed four EVAs totaling over 25 hours, (one of which lasted for eight hours and 29 minutes, and would be the longest until STS-102 in 2001), and it was the first time three astronauts performed a space walk together. [Read more]

6. June 18, 1983: STS-7, Challenger The second launch for Challenger brought along the largest crew so far — five astronauts at once — as well as Sally Ride, the first American woman in space (pictured above). Going forward, NASA would responsible for quite a bit of diversity in space, including but not limited to the first African American, Canadian, Arab and Mexican. The Space Shuttle program continued to work on deploying satellites: two communications satellites for Canada and Indonesia, and a Shuttle Pallet Satellite, which was a test platform developed by an aeronautics firm from West Germany. The pallet satellite system would be used in future missions, as it allowed space-based experiments to be carried out in the bay of the shuttle as well as free-flying in the vacuum. [Read more]

9. January 28, 1986: STS-51-L, Challenger In the first major disaster for the Space Transportation System, Space Shuttle Challenger tragically exploded 73 seconds after lift-off during the program's 27th mission, killing all seven of the crew. The accident was broadcast live to a stunned American audience, and seen by family members of the astronauts in person at Cape Canaveral. STS-51-L marked the first time a civilian was taken up on a mission: on the patch is an apple next to the name of Christa McAuliffe, who taught high school. After several missions every year up until the Challenger disaster, the next wouldn't launch for well over two years. [Read more]

19. May 16, 2011 (planned): STS-134, Endeavour This Monday, if Endeavour isn't delayed again, will be the shuttle's final mission before its retirement. Endeavour is the youngest shuttle in the fleet, but was no slouch, with 280 days spent in space during 25 missions and over 4,400 orbits. Endeavour was actually supposed to be decommissioned back in 2010, but NASA delayed the shuttle's final mission until this year. The agency plans to turn the spacecraft over to the California Science Center in Los Angeles, though its Canadarm will go to a museum in that country. Pictured above: Endeavour in a storm before its first scheduled launch on April 29. [Read more] [Update: STS-134 launched]