Nasa's Atlantis shuttle launches from the Kennedy Space Center
The US space shuttle Atlantis has blasted off to the International Space Station to deliver spare parts - and up to a million microscopic worms.
The mission is set to include three spacewalks to store hardware on the outside of the orbiting outpost.
The worms are for experiments that aim to help scientists understand why human muscles waste away in zero gravity.
The species Caenorhabditis elegans, can sometimes be found in rubbish tips, where they feed on bacteria.
There are just five more shuttle launches scheduled before the planned retirement of the fleet in 2010.
Atlantis launched at 1928 GMT (1428 EST) on Monday from the Kennedy Space Center near Cape Canaveral, Florida.
The worms are for a study on muscle protein degradation
This mission is dedicated to building up the store of replacement parts on the space station, which is nearing the completion of its construction phase.
These spares include pump modules, gas tanks, two control moment gyroscopes and components for the space station's robotic arm.
Nasa wants to stock the station with as many of these as possible before the three shuttles retire. None of the other visiting spacecraft is big enough to carry such large pieces.
Five down, five to go
But the astronauts will also help prepare the way for the next shuttle mission, during which the last US space station module will be delivered: the Tranquility node with its attached cupola.
The cupola is a window module to provide crew members with a direct view of operations outside the space station and an observation point for watching the Earth.
A scarf belonging to American aviation pioneer Amelia Earhart has been brought along for the ride by mission specialist Randy Bresnik. Mr Bresnik's grandfather Albert was Earhart's only authorised photographer.
The six all-male crew of Atlantis will spend the US Thanksgiving holiday in orbit.
They will return to Earth with a seventh crew member, Nicole Stott, who has been living at the space station for nearly three months.
But this will be the last such shuttle crew rotation before the fleet's retirement in 2010.
The 11-day space outing will be the fifth and last shuttle mission for 2009.
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