The US space shuttle Endeavour has blasted off from Kennedy Space Center in Florida on its final voyage, which will deliver a pioneering physics experiment to the International Space Station.
Endeavour left the launch pad at 8.56am (1.56pm Irish time) carrying a six-member crew.
NASA plans just one more shuttle mission this summer with sister ship Atlantis before ending the 30-year-old shuttle programme.
The flight is the 134th in shuttle programme history.
Sister ship Discovery completed its final mission in March.
Russian and European freighters will keep the station stocked with food, water and supplies in the immediate future.
NASA has hired two commercial companies - Space Exploration Technologies and Orbital Sciences Corp - to fly cargo to the station as well. The firms are expected to begin station deliveries next year.
Crew transportation will be handled solely by Russia until US companies develop the capabilities. Then NASA wants to buy flight services, rather than develop and operate its own fleet to ferry astronauts to the station.
The shuttles are being retired due to high operating costs and to free up funds to develop new spaceships that can travel beyond the station's 354-km-high orbit.
Endeavour, the youngest of NASA's shuttles, will be making its 25th flight. It was commissioned as a replacement for Challenger, the shuttle destroyed in a 1986 launch accident that killed seven astronauts.
Endeavour carries the $2bn Alpha Magnetic Spectrometer particle detector, a collaborative project of 600 physicists in 60 research organisations that is spearheaded by Nobel laureate Samuel Ting of the Massachusetts Institute of Technology.
Once attached to the station, the detector will analyse high-energy cosmic rays for signs of dark matter, antimatter and other exotic phenomena.
The shuttle also will deliver a pallet of spare parts to the station.
The crew, led by Mark Kelly, is scheduled to spend 12 days at the station, helping to prepare it for operations after the shuttles are retired.
Kelly is married to US Representative Gabrielle Giffords, who is recovering from a gun attack in January that killed six and left 12 others injured.
The Arizona Democrat left her rehabilitation hospital in Houston on Sunday and travelled to Florida to watch Endeavour's launch.
