Los Angeles Times

BEIJING — China has spent billions of dollars to build a nationwide surveillance network. By one 2013 estimate, the country had 30 million surveillance cameras in parks, on highways and even in taxis.

Now, there’s a very powerful eye in the sky that allows authorities to keep tabs on things: the Gaofen-1 satellite, which is capturing high-resolution images from 300 miles above the Earth.

Analysis of images captured by Gaofen-1 have enabled Chinese police to find fields of opium poppy and marijuana in northern China and uncover dozens of routes used by smugglers at the border with North Korea, the official New China News Agency reported Monday.

“Chinese scientists definitely did research before on utilizing satellite images to fight crimes,” Xie Tao, a professor who specializes satellite imagery at Nanjing University of Science and Technology, said in an interview. “But now, thanks to the high-resolution images provided by Gaofen-1, they’re finally confident enough to announce the results to the public.”

Gaofen-1 was launched in April 2013 and put into service in December. During the first few months of testing after its launch, the satellite (whose name means “high resolution”) provided data on earthquakes, floods and smog in China. The news agency said its cameras were capable of capturing objects as small as a bicycle.

But just because a satellite can photograph something doesn’t mean humans are always good at telling what the object really is. In the hunt for the missing flight Malaysia Airlines Flight 370 this year, for example, multiple satellite images were offered by different countries, including China, but the objects shown in photographs proved to be unrelated to the plane.

“To better analyze images captured by the satellite, a basic understanding of the conditions on the ground is essential,” Xie said. For example, when it comes to drug crops, “you need to know what other plants they have in the area before you can distinguish marijuana from the rest.”

Authorities may be having second thoughts about publicizing their capabilities. The space agency first posted a statement detailing the satellite’s usage in public security efforts on Friday. But after Chinese press reported on marijuana field find and other details Monday, the statement was removed from the agency’s website. And the Public Security Ministry early today denied the satellite found any cannabis farms.