Russian cosmonaut Oleg Kononenko, NASA's Don Pettit and the European Space Agency's Andre Kuipers blasted off from the Baikonur Cosmodrome in Kazakhstan on Wednesday for the space station, a $100 billion research complex that orbits about 240 miles above Earth.

Their two-day trip in the cramped capsule ended at 10:19 a.m. EST when the Soyuz slipped into the Earth-facing docking port on the station's Rassvet module.

"The Soyuz flies down the chimney of the International Space Station with an early Christmas present for the crew - a return to a steady-state six-person capability," said NASA mission commentator Rob Navias during a televised broadcast of the docking.

Kononenko, Pettit and Kuipers join station commander Dan Burbank and two cosmonauts, who have been aboard the orbital outpost since November 16.

The station has been short-staffed for most of the past three months. Crew flights to the station were delayed while Russian engineers scrambled to find and fix the cause of a Progress cargo ship engine failure on August 24.

The engine is virtually identical to one used on the Russian Soyuz capsules that ferry crew.

The accident was traced to contamination or a blockage in a fuel line. Russia beefed up its inspection and quality control systems and resumed flying on October 30.

With the return to a six-member crew, the station can resume full-time science operations, including medical research, physics experiments and astronomical observations.

The crew also will begin preparations for the arrival of the first commercial cargo ship.

Space Exploration Technologies, or SpaceX, is scheduled to launch its Falcon 9 rocket and Dragon capsule on February 7 for a trial run to the station.

The debut flight of a second U.S. supplier, Orbital Sciences Corp., is expected later in the year.

(Editing by Kevin Gray and Eric Beech)

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