The Atlantis space shuttle is set for launching later today after NASA announced it had finished all the preparations for the mission to deliver Europe's first permanent space laboratory to the International Space Station.
Five American and two European astronauts boarded the Atlantis in preparation for launching at 2:45 p.m. EST, from the Kennedy Space Center in Florida.
The shuttle is scheduled to arrive at the space station on Saturday.
NASA said the technical problems that delayed the launch twice in December last year, were rectified.
There were still concerns about the weather as the launch time approaches but the U.S. space agency's weather experts said the possibilities for the launch are still 30 percent on concerns of the effects of the tornadoes that swept through the southern United States , heading toward central Florida.
We are hopeful that the front will time its approach just to the north and give us a slight break in the clouds prior to our 2:45 launch time, said George Diller, launch commentator.
The shuttle's fuel tank was filled with 500,000 gallons of super-cold propellants, early on Thursday, for the 8 1/2-minute ride to the space.
The preparations for the launch neared to completion after the Russian cargo ship entered the docking port at the space station with food, fuel, water and other supplies for the crew.