The US space shuttle Endeavour, with six astronauts on board including an Italian, docked at the International Space Station (ISS) on Wednesday, NASA said.
The shuttle blasted off Monday on a 16-day mission to deliver a potent physics experiment to probe the origins of the universe.
After the Endeavour crew of six greeted the six astronauts already at the orbiting space labs, the team set about the first order of business by transferring the Express Logistics Carrier from Endeavour's robotic arm to the ISS.
The carrier holds extra parts for the space station, including an ammonia tank, a high-pressure gas tank, a cargo transport container, and a spare arm for the Canadian robot Dextre.
On Thursday, astronauts install the Alpha Magnetic Spectrometer-2, a $2 billion dollar, 15,000 pound (7,000 kilogram) particle detector.
The experiment will be left behind to scour the universe for hints of dark matter and antimatter over the next decade.
After the logistics carrier was unloaded, the astronauts were fast approaching the end of their day, with the Endeavour crew set to start their sleep shift at 3:06 Eastern time (1906 GMT) followed by the ISS crew at 5:30 pm (2130 GMT).
"The crew of 12 will be together until May 23, when space station crew members Dmitry Kondratyev, Cady Coleman and Paolo Nespoli undock and return home to Earth," NASA said.
The Endeavour mission, which will include four spacewalks, is being commanded by astronaut Mark Kelly, the husband of Democratic US Representative Gabrielle Giffords who is recovering after being shot in the head at a January political meeting with local voters.
The shuttle will remain at the station until May 30, returning to the United States on June 1.
The 30-year US space shuttle program formally ends later this year with the flight of Atlantis, leaving Russia's space capsules as the sole option for world astronauts heading to and from the orbiting research lab.
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