China has, so far, launched 17 return satellites for the purpose of investigating and protecting land resources, according to the Commission of Science, Technology and Industry for National Defense.

In the 1970s, China began its studies on satellite-based remote monitoring technology, in order to better use and protect the country's land resources.

Over the past two decades, China has sent out 17 return satellites using optical remote monitoring technology. The satellites have successfully collected data and information on the country's resources of land, agriculture, sea areas and forests.

China is one of a few countries that is able to launch return satellites independently, the commission said.

(Xinhua News Agency May 8, 2004)