Countdown clocks at the Kennedy Space Center began ticking down today toward the launch on Friday of the shuttle Endeavour, the next-to-last flight before Nasa ends the 30-year-old programme.
Lift-off is targeted for 3:47 pm (7.47 pm Irish time), sending Endeavour on its way to delivering the $2 billion Alpha Magnetic Spectrometer particle detector and spare parts to the International Space Station.
Endeavour commander Mark Kelly, who is married to stricken US Representative Gabrielle Giffords, said today his wife is looking forward to watching the launch.
Ms Giffords, an Arizona Democrat, has not been seen publicly since she was shot through the head outside a Tucson, Arizona, grocery store on January 8th. Six people died, and 12 others were injured in the attack. Ms Giffords is undergoing rehabilitation at a Houston hospital.
"She's been working really hard to make sure that her doctors would permit her to come. She's more than medically ready to be here and excited about making this trip," Mr Kelly told reporters shortly after he and his five crewmates arrived at the Florida spaceport to prepare for launch.
The launch also has drawn the attention of president Barack Obama, who plans to be at Kennedy Space Center on Friday with his family to watch Endeavour fly.
Just one launch remains after Endeavour returns from its 25th and final space flight, the 134th in shuttle program history. The shuttle Atlantis is scheduled to close out the 30-year-old shuttle programme this summer after flying a last load of supplies to the station.
Nasa already has turned over space station crew flights to Russia and will rely on new commercial carriers Space Exploration Technologies and Orbital Sciences to deliver US cargo to the outpost.
The shuttles are being retired due to high operating costs and to free up funds to develop spaceships that can travel beyond the station's 350 km orbit.
Endeavour, which has been promised to the California Science Center in Los Angeles upon its return, was the replacement ship for Challenger, which was lost in a 1986 explosion as it ascended over the Atlantic that killed seven astronauts.
It will be the second of Nasa's three surviving shuttles to be retired. Sister ship Discovery, which will be transferred to the Smithsonian National Air and Space Museum, completed its last flight in March.
Atlantis' final launch is scheduled for June 28th.
Reuters