Most observation satellites are placed in orbit a few hundred kilometres above the planet, but the Gaofen-4 satellite, the latest in China’s global high-definition monitoring network, operates at 36,000km above sea level.

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The European Space Agency conducted research in 2010 on the feasibility of sending an observation satellite to high altitude orbit, but thought it impossible to spot an object smaller than 1km in length with the existing technology.

The Gaofen-4 has achieved an optical resolution of 50 metres, according to the Chinese space authorities.

To put that into perspective, the camera could take a picture of an area the size of Henan province, bigger than Greece, an official in charge of the project said, yet the photo is clear enough that you can spot a large ship in the water.

The satellite operates on a so-called geostationary orbit, which allows it to appear stationary in the sky and view the same point on earth continuously.

Low-orbiting satellites constantly move around the earth and can only take a snapshot of a region during a fly-by.

Flying high also gives a satellite a birds-eye view over a larger area.

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Gaofen-4 lets China to “take as many selfies as it likes without troubling passers-by”, said Professor Jin Linhai, a researcher at the Chinese Academy of Sciences’ Institute of Remote Sensing and Digital Earth.

The Gaofen-4 also carries a heat sensor with a 400-metre resolution to monitor forest fires, extreme weather events and other natural disasters in China and nearby regions, according to the Chinese government.

Experts, however, have questioned China’s claims that the satellite camera has the most powerful resolution for satellites in high orbit.

A 50-metre resolution was good, but China may still trail the West and Russia in the development of high-definition sensors, according to Jin.

The United States and Russia have sent numerous reconnaissance satellites into high altitude orbit over the decades, but they kept the level of camera and imaging resolutions classified and they could be higher than that claimed by China, he said.

Satellites operating in low orbit already have imaging devices that work at much higher resolutions, with some commercial probes able to show detail at less than one metre.

Jin said it was difficult to say whether the benefit of a high-altitude observation satellites could justify the costs, which were not revealed in the latest mission by the Chinese government.

Gaofen-4 would, however, have practical uses and give China a strategical hold on an orbiting position higher than most observation satellites around the earth, he said.

The United States Air Force launched a couple of spy satellites last year into high, geostationary orbit to monitor the space devices of other nations on the same strategic altitude.

Pavel Machalek, the chief executive of the satellite imagery service provider Spaceknow Inc in the United States, said the deployment of Gaofen-4 would “present an interesting and exciting source of geospatial data” if China was open to sharing it.

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The Chinese government said it would share the images of its Gaofen project, which will have a network of eight satellites with global coverage by 2020.

China’s next challenge would be in the analysis and exploitation of the data, according to Machalek.

US and European companies already automate many jobs ranging from car counting to the “monitoring of construction at the China controlled Spratly Islands”, he said.

“We envision Chinese companies and the government would soon have these capabilities,” he said.