On April 12th, it was announced by the China National Space Administration that the Queqiao-2 relay satellite has successfully completed in-orbit communication tests. After evaluation, both the platform and payload of the relay satellite are functioning normally, meeting all mission requirements in terms of functionality and performance. It is now capable of providing relay communication services for the fourth phase of lunar exploration projects and future domestic and international lunar exploration missions. This marks a complete success for the mission.
On March 20, 2024, the Long March 8 carrier rocket's satellite platform camera captured images of the separation of the Queqiao II relay satellite and the carrier rocket. The solar panels and umbrella antennas were successfully deployed, with the Tianhe experimental satellite visible on the left side of the image. Image courtesy of the China National Space Administration.
Since its launch on March 20, the Queqiao II relay satellite has undergone mid-course corrections, lunar braking, and lunar orbit maneuvers. On April 2, as planned, it entered a 24-hour period elliptical orbit around the moon. On April 6, the Queqiao II successfully completed a communication test with the Chang'e 4 probe, which is conducting exploration on the far side of the moon. From April 8 to 9, the Queqiao II conducted communication tests with the Chang'e 6 probe (ground status).
The Tianhe-1 and Tianhe-2 communication technology test satellites, launched synchronously, entered lunar orbit on March 29 and successfully separated on April 3. They are currently conducting a series of communication technology verifications.
On April 8, 2024, Tianzhou-2 captured this image, with Earth appearing as the smaller celestial body in the background. Image provided by the China National Space Administration.
The Queqiao relay satellite and Tianhe test satellite adopt a circumlunar large elliptical frozen orbit as their mission orbit. Due to the irregular shape of the moon, spacecraft flying near it are subject to factors such as lunar gravity, which can cause deviations in their flight paths. The circumlunar large elliptical frozen orbit is a stable orbit around the moon, and spacecraft flying in this orbit can minimize deviations in their flight paths.
Choosing the circumlunar large elliptical frozen orbit as the mission orbit for Queqiao has several advantages. Firstly, it increases communication speed. Compared to Queqiao, Queqiao-2's mission orbit is closer to the moon, significantly boosting the data transmission communication rate. Secondly, it provides better coverage of lunar south pole communications. Compared to Queqiao, which orbits around the Earth-Moon Lagrange L2 point, Queqiao-2's visibility of the lunar south pole is significantly enhanced in the circumlunar large elliptical mission orbit, greatly improving communication coverage of the lunar south pole region. Thirdly, it saves satellite fuel. Queqiao-2 can maintain long-term residence in this orbit with minimal fuel consumption.
In the future, the Queqiao relay satellite will provide relay communication services for the Chang'e-4 and upcoming Chang'e-6 missions as planned, and will opportunistically carry out corresponding scientific exploration.
