​Beijing, June 13 (IANS) China's first high-orbit remote sensing satellite, Gaofen-4, has been activated after six months of in-orbit testing, the State Administration of Science, Technology and Industry for National Defense (SASTIND) announced on Monday.

Gaofen-4 is China's first geosynchronous orbit high-definition optical imaging satellite and the world's most sophisticated, Xinhua reported.

Unlike Gaofen-1 and Gaofen-2 in low-orbits around the Earth, Gaofen-4 is orbiting at 36,000 km. High-orbit satellites have the advantage of being able to photograph "grand scenarios". Low-orbit satellites, in contrast, can see more detail at faster speed.

Low-orbit satellites cannot always follow natural disasters, but Gaofen-4 can continuously observe a disaster because it moves synchronously with the Earth.

It improves the response to disasters like earthquakes, landslides and typhoons with its high-precision sensors.

Gaofen-4, which was launched in December 2015, has a designed lifespan of eight years, compared to other remote sensing satellites which remain in service for less than three to five years.

During the in-orbit test, Gaofen-4 has been used to collect imageries of flood-hit areas in south China and monitor fires that occurred in Sichuan province and Russia.

China started the Gaofen project with the launch of Gaofen-1 in April 2013. It aims to launch seven high-definition observation satellites before 2020, designed for disaster prevention, surveillance of geological disasters and forest disasters and weather forecast.

Gaofen-3 is set to be launched in August 2016, according to the SASTIND.​