HELSINKI — China’s Queqiao-2 communications relay satellite entered lunar orbit March 24, paving the way for a lunar far side sample return mission.
Queqiao-2 began a 19-minute-long braking burn at 12:46 p.m. Eastern Sunday (1646 UTC), allowing the spacecraft to be captured by the moon’s gravity, the China National Space Administration (CNSA) announced early March 25.
The spacecraft is expected to have entered an initial 200 by 100,000-kilometer lunar orbit. Operators will further alter its orbit and inclination to bring Queqiao-2 into a 200 by 16,000-km, highly-elliptical “frozen” orbit.
Queqiao-2 will have simultaneous direct line-of-sight with both ground stations on Earth and the lunar far side for large portions of this 24-hour-period orbit. This frozen orbit is intended to be highly stable and require little maintenance, boosting mission longevity.
China intends to launch its Chang’e-6 spacecraft in May to attempt to collect samples from the far side of the moon. The far side of the moon never faces the Earth, as the planet’s gravity has slowed the rotation of the moon over time. Queqiao-2 is thus required for communications for the mission.
Queqiao-2 launched on a Long March 8 rocket from Wenchang spaceport March 19. The spacecraft embarked on a 112-hour voyage to the moon. China’s space authorities did not provide updates on trajectory correction maneuvers implemented during the journey.
Two smaller lunar spacecraft—Tiandu-1 and Tiandu-2—were also aboard the launch. These performed their own synchronized burns at 1:43 p.m., successfully entering lunar orbit.
The experimental satellites will fly in formation in lunar orbit and conduct tests for navigation and communications technology verification. These are pathfinders for a planned wider Queqiao constellation to provide lunar navigation and communication services. Tests will include satellite-to-ground laser ranging and inter-satellite microwave ranging methods.
Lunar far side and south pole support
The 1,200-kilogram Queqiao-2 satellite carries a 4.2-meter parabolic antenna and is part of China’s plans for future lunar exploration and a stepping stone towards building a lunar base in the 2030s.
It is expected to support the ongoing Chang’e-4 lunar far side lander and rover mission after assisting Chang’e-6. It will also shift its orbit into a 12-hour period to support the 2026 Chang’e-7 and later Chang’e-8 missions.
These later missions will target the lunar south pole to detect volatiles and potential resources on the moon. The latter will also test in-situ resource utilization techniques, such as using lunar regolith to produce bricks. The missions are precursors to the International Lunar Research Station (ILRS).
By comparison, NASA’s Artemis program infrastructure will include the Gateway. This will act as a communication hub, science laboratory, short-term habitation module, and holding area for other spacecraft.
Queqiao-2 also carries three payloads as part of the science objectives of the 2026 Chang’e-7 mission. These are an extreme ultraviolet camera and an array neutral atom imager. An Earth-moon length baseline very long baseline interferometry (VLBI) experiment with utilize the large antenna.
The spacecraft could also support other countries’ lunar efforts. “It is possible to provide relay communication services for other lunar landing exploration missions at the lunar south pole or lunar far side in the future,” an official from DFH Satellite, under the China Aerospace Science and Technology Corporation (CASC), said in 2023.
“China’s lunar exploration program has always valued international cooperation and has always been open to international cooperation,” Ge Ping, deputy director of the Center of Lunar Exploration and Space Engineering of China (LESEC) under CNSA, told CCTV.
China is actively engaging countries, space agencies and academic and other entities in order to attract them to its ILRS initiative.
Queqiao-2, or “Magpie Bridge-2”, is a more capable follow-up to Queqiao, launched in 2018. The earlier satellite facilitated the Chang’e-4 mission—the first-ever lunar far side landing. The aging Queqiao relay satellite remains operational in a halo orbit around the Earth-moon Lagrange point L2. The spacecraft orbits roughly 70,000 kilometers beyond the moon.
