China completes year-long Earth-Moon bidirectional laser communication test

The Chinese Academy of Sciences has announced the successful completion of over one year of testing for a bidirectional laser communication link between Earth and the Moon. Using telescopes in Yunnan province and an experimental satellite, the project achieved a downlink speed of 100 Mbps and an uplink speed of 1.25 Mbps over a distance of approximately 400,000 kilometers.

This achievement makes China the second nation, after the United States, to demonstrate two-way lunar laser communication. While the technology offers higher bandwidth potential than traditional microwave radio signals, the data rates achieved are lower than previous benchmarks. For comparison, NASA’s 2013 lunar laser demonstration recorded download speeds of 622 Mbps and upload speeds of 20 Mbps.

Maintaining a stable laser beam at such vast distances presents significant technical challenges. Yang Lei, the head of the research team, described the difficulty of Earth-Moon communication as being akin to “threading a needle at a distance of a thousand kilometers,” noting that even microscopic vibrations or atmospheric disturbances can cause the beam to miss its target by hundreds of kilometers.