Beijing ? A Chinese astronaut celebrated his birthday in orbit on Thursday, as the flight of his Shenzhou 6 capsule entered its second day, setting a new record for the length of a Chinese space mission.

Fei Junlong and Nie Haisheng blasted off Wednesday on China’s second manned space mission, a costly project meant to affirm Beijing’s status as a rising world power.

On Thursday, they were to test the capsule’s stability by carrying out tasks such as opening and closing the door, the official Xinhua News Agency said. State television showed live scenes of the astronauts taking off their bulky, 22-pound spacesuits and moving around their cabin.

Nie was celebrating his 41st birthday in orbit.

Early Thursday, the mission exceeded the 21 1/2 hours that astronaut Yang Liwei spent in orbit on China’s first space flight in 2003. That mission made China only the third nation to send a human into space on its own, after Russia and the United States.

By noon Thursday, the Shenzhou 6 had circled Earth 18 times, Xinhua said, giving it a rate of one orbit about every 90 minutes. It said the capsule was traveling at 4.9 miles a second, or about 17,528 mph.