Published : 21/05/2025

On May 21, 2018, China's Queqiao relay satellite (「鵲橋」中繼星) was launched into the sky.

The Queqiao relay satellite is the world's first communication satellite operating at the Earth-Moon Lagrange L2 point.

It provides relay communication between Earth and the Moon for the Chang'e-4 soft-landing exploration mission on the far side of the Moon at the end of the same year.

Wu Weiren, the chief designer of the China Lunar Exploration Project, explained that because the period of the Moon's revolution around the Earth is the same as the period of the Moon's rotation, the far side of the Moon will always face away from Earth.

When the Chang'e-4 conducts the world's first soft landing and patrol exploration mission on the far side of the Moon, it is unable to directly communicate with Earth and transmit data due to the obstruction of the Moon itself.

The role of the Queqiao relay satellite is to serve as a communication "relay station" between Chang'e-4 and Earth.