China sends a highly sophisticated Earth-observation satellite, Gaofen-4, to space on Dec. 28, 2015. Gaofen-4 is China's first HD optical imaging satellite in a geosychronous orbit.

The launch date of the satellite is kept highly confidential by China. The launch was just known to the public when the confirmation of a successful launch was released on the state-run media three hours after. Gaofen-3 is launched from the Xichang Satellite Launch Center in the province of Sichuan at 00:004 a.m. It is carried by a Long March-3B carrier rocket. This is the 222th flight of the Long March rocket series.

Gaofen-4  is part of a much larger Gaofen project that aims to launch seven high-definition observation satellites before 2020. The first Gaofen satellite sent to space, Gaofen-1, was sent in April 2013. Gaofen-1 and Gaofen 2 are rotating in low orbits (600-700 km) around Earth. Gaofen-4 is located way above them at 36,000 kilometers away from Earth. Gaofen-4 also moves in sync with the Earth.

The high-definition optical equipment on Gaofen-4 is powerful enough that it can capture an oil tanker traveling on the sea. It has a large CMOS camera that is considered one of the best in imaging for a global high-orbit remote sensing satellite.

The main purpose of the satellite will be for disaster prevention, as well as relief. The satellite is expected to complete surveillance of geological disasters as well as forest anomalies and, also, the usual meteorological forecast.

"The main breakthrough of Gaofen-4 is it will realize high-precision survey and image synthesis, long-distance imaging and data processing and transmission," said Li Bin of the Department of International Relations at Tsinghua University.

By 2016, China is set to return to human space flight. Shenzou-11 is planned to send manned missions to space. The exact launch date is yet to be determined and is expected to be known only until the launch is successful.