Astronauts carrying out China's second manned space mission made minor adjustments to the position of their craft Friday after it started moving too close to the Earth, the government said.
The Shenzhou 6 capsule is orbiting about 343 kilometers (210 miles) above the Earth, making one circle of the planet about every 90 minutes.
Astronauts discovered the craft had "slightly deviated from its designed orbit" and was moving a little closer to the Earth due to gravity, the official Xinhua News Agency reported.
At 5:56 a.m. Beijing time (2156 GMT), adjustments that lasted just a few seconds were made and the craft's original trajectory was restored, Xinhua said.
The report did not suggest the spacecraft was in any danger and called the adjustments a "maintenance operation."
Astronauts Fei Junlong and Nie Haisheng blasted off Wednesday on China's second manned space mission, an effort by the communist government to win respect abroad and public support at home.
The mission marks the second time the China's space program has sent humans into space.
By the time the orbital adjustments were made early Friday morning, the Shenzhou 6 had circled Earth 30 times, Xinhua said, giving it a rate of one orbit about every 90 minutes. It said the capsule was traveling at 7.8 kilometers (4.9 miles) per second, or about 28,080 kph (17,528 mph).
The government has not said how long Fei and Nie would stay up, but news reports said it could be three to five days. Xinhua reported that they had food and water for a week.
A Shanghai newspaper, the Morning Post, cited unidentified sources that said the capsule was to land Saturday in China's northern grasslands.
Recovery crews spent Thursday practicing rescue work, launching helicopters to the primary landing area in the Inner Mongolia region, Xinhua said.
Early Thursday, the crew set a Chinese endurance record in space, surpassing the time of country's first manned space flight in 2003, when astronaut Yang Liwei spent 21 1/2 hours in orbit.
Communist leaders hope the manned space program's triumphs will stir patriotic pride, shoring up their standing amid public anger at corruption and a growing gap between rich and poor.
The Shenzhou _ or Divine Vessel _ capsule is based on Russia's workhorse Soyuz, though with extensive modifications. China also bought technology for space suits, life-support systems and other equipment from Moscow, though officials say all of the items launched into space are made in China.
China has had a rocketry program since the 1950s and sent its first satellite into orbit in 1970. It regularly launches satellites for foreign clients aboard its giant Long March boosters.
Chinese space officials say they hope to land an unmanned probe on the Moon by 2010 and want to launch a space station, AP reported. V.A.