Space Shuttle Endeavour has returned to Earth after spending more than a week at the International Space Station to make construction upgrades.
Pilot Terry Virts guided the shuttle back to the runway at Kennedy Space Center in Florida, ending a 14-day mission in space. NASA engineers welcomed the crew after touchdown.
Endeavour delivered two key additions to the space station - the Tranquility node and the Cupola observatory. The European Space Agency built both modules as part of the international effort to build up the station's facilities to support more astronauts and advance scientific work in space.
Tranquility is a seven-meter long node that offers more room for crew members and crucial equipment, such as the station's air processing and water recycling systems. It also provides three new berthing points for space shuttles and other crew vehicles that dock to the station.
The Cupola observatory has six windows along one side, and another on top, to give crew members a panoramic view of the station and the Earth. The module also contains a robotic work station, and the windows are crucial for astronauts to watch the robot arm as they operate it.
NASA officials say the latest shuttle mission also provided an opportunity for crew members and the five space station residents to compete in their own version of the Winter Olmypics. Pilot Terry Virts performed a weightless luge run, and Japanese astronaut Koichi Wakata used a pair of short skis for a slalom and a jump.
NASA officials say, after the Endeavour mission, construction work on the space station is about 90 percent complete. Only five shuttle missions remain before the shuttle fleet is due to be retired. T he next shuttle mission is set to launch in April to deliver additional equipment to the station.