You won't want this video to end. Go behind the scenes on the space shuttle Endeavour's final flight, and the second to the last flight in NASA's space shuttle program. It's also the final mission for the legendary shuttle commander, astronaut Mark Kelly, who is now retiring from NASA.Here's a little background. Endeavour was the fifth and final NASA space shuttle to be built, a replacement for the lost shuttle Challenger. Since 1992, it has successfully flown 25 missions, playing an instrumental role in servicing the Hubble Space Telescope and in the construction of the International Space Station.Among Endeavour's missions was the first to include four spacewalks, and then the first to include five. Its STS-67 mission set a length record almost two full days longer than any shuttle mission before it. Its airlock is the only one to have seen three spacewalkers exit through it for a single spacewalk. And in its cargo bay, the first two pieces of the International Space Station were joined together. On STS-134, Endeavor delivers a new, cutting edge science experiment to the space station: the Alpha Magnetic Spectrometer. It's a state-of-the-art, high energy particle physics experiment built in Geneva by a collaboration of 16 different countries. It will search for clues on what the universe is made of and how it began, the origin of dark matter, antimatter and strangelets, pulsars, blazers and gamma ray bursters. And that's just the beginning what the scientists might detect.