China launched three military surveillance satellites Sunday aboard a Long March 4C rocket, but government officials are keeping their mission a secret.

Credit: Xinhua
 
The Yaogan 17 payload, described by Chinese state media as a single satellite, launched at 1916 GMT (3:16 p.m. EDT) Sunday on a Long March 4C rocket from the Jiuquan space center in northwest China's Gobi desert.

The three-stage, liquid-fueled rocket placed the Yaogan 17 payload in a 680-mile-high orbit with an inclination of 63.4 degrees.

China's state-run Xinhua news agency reported the payload would conduct scientific experiments, carry out land surveys, monitor crop yields and aid in preventing natural disasters. But analysts believe the launch's passengers were three intelligence-gathering satellites.

Yaogan 17's altitude and inclination match the orbits of two other Chinese launches in 2010 and 2012. Each of those launches deployed three satellites in orbit, and U.S. military tracking data indicate Sunday's launch also released multiple spacecraft after arriving in space.

The Yaogan triplets could collect intelligence on naval vessels, according to Western space analysts. Satellites operated by the U.S. National Reconnaissance Office flying in similar orbits are believed to monitor global naval activity.

Sunday's mission was the sixth Chinese space launch of the year.