THE space shuttle Endeavour is set to embark on its 25th and final flight today to deliver the $2bn Alpha Magnetic Spectrometer to the International Space Station.
The flight will be the 134th for NASA's shuttle program, with one mission to follow this summer before the fleet is retired.
Gabrielle Giffords, the congresswoman who was shot in the head by a gunman in Tucson, Arizona in January, arrived in Florida last night for the launch of the shuttle that will be commanded by her husband, Mark Kelly.
After its mission, Endeavour will go on display at the California Science Centre in Los Angeles.
The spectrometer will make detailed studies of high-energy cosmic rays. The device, built by a consortium of 60 research agencies, will be mounted outside the space station.
Shuttle astronauts will conduct four spacewalks to install a materials science experiment, refill an ammonia coolant reservoir and perform other station maintenance.