The US space shuttle Endeavour blasted off from Kennedy Space Centre in Florida today on its final voyage to deliver a pioneering physics experiment to the International Space Station.
Endeavour roared off the launch pad at 8.56am local time (1.56pm Irish time), carrying a six-member crew.
Nasa had hoped the shuttle would be back from its final space mission by now, but the first launch attempt on April 29th was scuttled after a heater in one of the ship's hydraulic power generators failed.
The flight is the 134th in shuttle programme history and the next-to-last before Nasa retires its three-ship fleet. Sister ship Discovery completed its final mission in March and Atlantis is schedule to close out the program with a last cargo haul to the station in July.
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 350km-high orbit.
Endeavour, the youngest of Nasa's shuttles, will 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 first flew in 1992.
Endeavour carries the $2 billion 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 spare parts to the station.
The six-man veteran crew, led by Commander Mark Kelly, is scheduled to spend 12 days at the station, helping to prepare it for operations after the shuttles are retired.
Cmdr Kelly is married to US congresswoman Gabrielle Giffords, who is recovering from an assassination attempt in January that killed six and left 12 others injured. The Arizona Democrat left her rehabilitation hospital in Houston yesterday and traveled to Florida to watch today's launch.
Reuters