The second spacewalk will take place Saturday. Also, astronauts inside will test a new processor that converts urine into drinking water.

Discovery was launched into space Sunday night. During its stay with the station, three spacewalks will be conducted by astronauts. If all goes well, it is scheduled to undock from the station on March 25, towards a planned March 27 landing at the Kennedy Space Center in Florida.

Space shuttle Discovery crew member Steven Swanson works outside the international space station during a space walk orbiting Earth, Thursday, March 19, 2009. Astronauts aboard the U.S. space shuttle Discovery unfurled the International Space Station's fourth and final set of solar array wings, bringing the 10-year-old space station to full power, which is critical for boosting science research and allowing the crew to double to six.(Xinhua/AFP Photo)

Space shuttle Discovery crew member Steven Swanson works outside the international space station during a space walk orbiting Earth, Thursday,  March 19, 2009. Astronauts aboard the U.S. space shuttle Discovery  unfurled the International Space Station's fourth and final set of solar array wings, bringing the 10-year-old space station to full power, which is critical for boosting science research and allowing the crew to double to six.(Xinhua/AFP Photo)

Editor:Yang Jie