TIANJIN - A senior scientist working on China's lunar orbiter project said Wednesday that China has not yet created a timetable for its manned moon landing program.

"Putting a man on the moon involves a very complicated systematic program with many technical challenges to solve, including those related to conducting space walks, docking, staying on the moon and returning," Ouyang Ziyuan, chief scientist for the lunar orbiter project, said at a conference of the Academy of Sciences for the Developing World held in north China's city of Tianjin.

"China won't carry out a manned moon landing until it masters all of these crucial technologies," said Ouyang, who is also an academician with the Chinese Academy of Science.

Ouyang said China's lunar probe projects currently consist of unmanned moon exploration, a manned moon landing and the building of a moon base.

"China is currently in the first stage," Ouyang said, adding that the first stage involves the orbit, landing and return of lunar spacecraft.

China launched its Chang'e-1 orbiter in 2007 and Chang'e-2 in 2010. The first probe retrieved a great deal of scientific data and a complete map of the moon, while the second created a full high-resolution map of the moon and a high-definition image of Sinus Iridium, a lunar landmark.

China is scheduled to send its third probe, the Chang'e-3, to the moon in 2013 and retrieve it in 2017 after sampling the moon's surface, Ouyang said.

The completion of the three steps will pave the way for a manned lunar mission in the future, he said.