Inter-satellite laser communication channels as a solution to the problem of limited global coverage by ground stations in China
On Thursday, China successfully launched a group of satellites, probably designed to test inter-satellite laser communications. This launch was an important step in the implementation of major projects to create satellite constellations of the country.
The Long March 2D launch vehicle with the Yuanzheng-3 upper stage, capable of multiple activation, launched on December 12 from the Jiuquan Cosmodrome. During takeoff, the rocket dropped thermal insulation tiles, rising on a hypergolic mixture of fuel components.
The Corporation of China Aerospace Science and Technology (CASC), the country's main contractor in the field of space and the state defense giant, confirmed the successful launch a few hours after launch, when the upper stage of the YZ-3 brought all payloads into pre-set orbits through a series of engine starts.
CASC reported that the payloads are "five satellites forming a high-speed laser diamond orbital constellation." Although CASC did not provide details about the specifications of the satellites, their name Diamond Constellation suggests that they are designed to test inter-satellite laser communication channels.
The American space surveillance system tracked five launch-related payloads in three different orbits. One satellite is in an orbit with an altitude of 988 x 1160 kilometers, the other is in an orbit of 791 x 812 km, and the other three are approximately in orbits of 975 x 990 km. All orbits are tilted at an angle of 59.9 degrees.
Inter-satellite laser communication channels will be useful for the implementation of Chinese mega-constellation projects, such as the Guowang National Grouping and the Shanghai-supported Qianfan/Thousand sails grouping. Inter-satellite laser communication channels can help solve the problem of limited global coverage by ground stations in China, which is especially important due to its dependence on on-board space situational awareness systems.
Changguang Satellite, a commercial operator of remote sensing of the Earth, allocated from the Chinese Academy of Sciences, demonstrated space-earth laser communication channels in 2023.
This launch was the fourth for the YZ-3 upper stage, designed for use with the Long March 2D launch vehicle. Earlier this year, the Yuanzheng-1A upper stage failed during the launch of the Long March 2C launch vehicle with the DRO-A and DRO-B lunar satellites. However, the satellites used onboard thrusters to reach their intended lunar long-range retrograde orbits several months later.
The last failure of the Long March rocket occurred in 2020, more than 200 launches ago, when a commercial Indonesian communications satellite was lost due to an anomaly with the third stage of the Long March 3B launch vehicle.
Thursday's launch was China's 63rd attempt to put satellites into orbit in 2024. The country could surpass its national record of 67 attempts set last year, thanks to a series of Long March rocket launches and possible commercial launches of solid-fuel rockets scheduled for mid- and late December.
The Long March 5B launch vehicle is preparing for launch, which may be the first for satellites of the Guowang megastar from the Wenchang Cosmodrome on December 16. Long March 8 can also be launched from the new commercial spaceport on Hainan. The new cosmodrome hosted its first launch on November 30, which also marked the debut flight of the Long March launch vehicle, China's first single-stage medium—class launch vehicle developed by SAST.
