BEIJING, Dec. 16 (Xinhua) -- China plans to launch lunar probe Chang'e-5 in 2017, according to the State Administration of Science, Technology and Industry for National Defense.

"The development of Chang'e-5 is proceeding smoothly," said the administration's spokesman Wu Zhijian at a press conference on Monday.

The just-concluded Chang'e-3 mission marked completion of the second phase of the country's lunar program, which includes orbiting, landing and returning to Earth.

The lunar program will enter the next stage of unmanned sampling and returning, which will include Chang'e-5 and 6 missions, according to Wu.

"The program's third phase will be more difficult because many breakthroughs must be made in key technologies such as moon surface takeoff, sampling encapsulation, rendezvous and docking in lunar orbit, and high-speed Earth reentry, which are all new to China," Wu said.

As the backup probe of Chang'e-3, Chang'e-4 will be adapted to verify technologies for Chang'e-5, according to Wu.

China's Chang'e-1 and Chang'e-2 missions were in 2007 and 2010.

Launched on Oct. 1, 2010, Chang'e-2 is about 65 million km from Earth and is China's first man-made asteroid. It is heading for deep space.

"The completion of the third phase will not mean an end of China's lunar probe program," Wu said. "It should be a new starting point."

Wu, however, said follow-up plans for lunar exploration after the third phase is completed are still being studied.

As for deep space exploration, Wu said, "Experts have reached some consensuses and scientists are studying and drawing up integrated plans."

Chang'e-3 lunar probe succeeded in soft landing on the moon Saturday evening. The country's first moon rover, which was on board the probe, separated from the lander early on Sunday. The two photographed each other on the moon's surface Sunday night.

Under the program, China has made breakthroughs in key technologies, which have enabled the lunar probe to land on the moon and deploy a moon rover, Wu said.

"We have also laid a solid foundation for future exploration of deep space," he said.

In response to questions about working with other countries in this field, Wu said China is always positive about international cooperation in lunar exploration.

"We have had very good cooperation with other countries and international organizations in previous missions," he said.

Data collected through the Chang'e-1 and Chang'e-2 probes are open to scientists across the world, according to Wu.

China shared information collected by Chang'e-1 with the European Space Agency (ESA), and an ESA aerospace control center and three of its telecommand telemetry control stations took part in the Chang'e-3 mission, he said.

"In the next stage of the lunar program, there will be more international cooperation," he said.

"Despite current progress, China still lags behind space giants like the United States and Russia in many aspects," he said. "We need to work harder and move faster."