China demonstrates its first high-speed two-way laser link between Earth and Moon

China has demonstrated its first high-speed, two-way laser communication link across more than 400,000 kilometres between Earth and the Moon. The achievement extends the country’s space laser communications capability beyond low Earth orbit and into cislunar space.

The experiment reached preliminary speeds of 1.25 megabits per second from Earth and 100 megabits per second on the return link. At that downlink rate, an 8K image of the lunar surface could be transmitted in about 12 seconds, compared with roughly four to five minutes using a conventional microwave link.

Maintaining a narrow laser beam over such a distance required the satellite and ground telescope to remain precisely aligned while moving. Researchers accounted for factors including orbital uncertainty, telescope installation errors, atmospheric refraction and the laser’s travel time. Because the returning signal was extremely faint, the team also used detectors capable of sensing individual photons, together with algorithms designed to separate useful data from background noise.

Laser links can offer high bandwidth, fast transmission, precise directionality and greater confidentiality, although their narrow beams make accurate targeting especially demanding. The demonstrated technologies could support data-intensive communications for future crewed lunar missions, lunar research facilities and deeper-space exploration.