The Chinese spaceflight monitoring ship "Yuanwang No. 3" has returned to the Jiangnan Port of Nanjing in East China's Jiangsu Province after successfully completing its mission with China's first experimental spacecraft "Shenzhou."

The other three monitoring ships, Yuanwang Nos. 1, 2 and 4, returned from their missions earlier.

This was the first time China's spaceflight monitoring ships voyaged on the Pacific, Indian, and Atlantic oceans, marking a breakthrough for the country's sea monitoring and control technologies for low-orbit spacecraft, experts say.

During their 259-day voyage, the four ships traveled some 62, 000 nautical miles and experienced some heavy seas while tracking and communicating with the "Shenzhou" for a total of 150 minutes.