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 last week.
Gaofen-4 is China's first geosynchronous orbit high-definition optical imaging satellite and the world's most sophisticated, according to state news agency Xinhua. It will orbit the Earth at an altitude of 36,000 kilometers.
Unlike Gaofen-1 and Gaofen-2, which are in low orbits around the Earth, Gaofen-4 is a high-orbit satellite. This allows it to photograph "grand scenarios". Low-orbit satellites, in contrast, can see more detail at faster speed, Xinhua explained.
One disadvantage of low-orbit satellites is that they cannot always follow natural disasters. Gaofen-4, with its geosynchronous position, can continuously observe a disaster because it moves synchronously with the Earth. This offers the potential to improve the response to disasters such as earthquakes, landslides and typhoons thanks to the satellite's high-precision sensors.
Gaofen-4 was launched in December 2015 and has a designed lifespan of eight years. During in-orbit tests the satellite was used to collect images of flood-hit areas in south China and to monitor fires that occurred in southwest China's Sichuan Province and in Russia.
China's Gaofen project began in April 2013 with the launch of Gaofen-1. Through the project, the country is planning to launch a total of seven high-definition observation satellites before 2020. These satellites are designed for disaster prevention, surveillance of geological disasters and forest disasters, and for weather forecasting, according to the SASTIND.
Gaofen-3 is expected to be launched in August 2016.