China develops communications satellite tech edge

China has become a leader in the cutting-edge technology of space-based, high-speed information transmission thanks to an advanced satellite, according to the National Space Administration.

The Shijian 13 communication satellite has conducted the world's first experiment on high-orbit laser communication, a technology crucial to enabling a spacecraft to send, receive and transmit a large quantity of data with ground stations, the administration said in a statement on Tuesday.

The experiment was one of the 11 technological demonstration programs made by Shijian 13, which is orbiting nearly 40,000 kilometers above the Earth, since it was lifted atop a Long March 3B carrier rocket from Xichang Satellite Launch Center in Sichuan province in April. It proved that the satellite is capable of carrying out steady, high-speed and high-quality transmission of information with the ground.

The fastest transmission speed recorded during the experiment was five gigabytes of data per second, which means a user could download a high-resolution movie within one second.

The administration said that the laser equipment was designed by Ma Jing and Tan Liying, two professors from Harbin Institute of Technology, and that the devices are the world's best of their kind in this field.

Shijian 13, developed by the China Academy of Space Technology and based on its DFH-3B communications satellite platform, has been called the country's most advanced communications satellite by the administration.

Weighing 4.6 metric tons, the satellite is expected to operate in a geostationary orbit for 15 years. It features a Ka-band broadband communications system capable of transmitting 20 gigabytes of data per second, exceeding the total capacity of all the country's previous communications satellites.

Shijian 13 uses an electric propulsion system, which allows it to carry more scientific instruments than previous satellites. At present, most satellites rely on chemical propulsion, which requires a relatively large amount of fuel that occupies space which could otherwise be used for scientific payloads.

Shijian 13 has been used to give 15 schools in southwestern China access to the internet, the administration said, explaining that students at those schools could not reach the internet because their schools are out of the reach of ground-based communications networks.

Wang Min, deputy head of the Institute of Telecommunication Satellite under the China Academy of Space Technology, previously said China plans to establish a constellation of advanced communications satellites based on the more advanced DFH 4 and DFH 5 platforms by 2025 and, after the plan is fulfilled, people will be able to use high-quality Wi-Fi services anywhere and anytime, including on bullet trains and planes.