China achieves lunar laser link but trails NASA's 2013 speeds
Synopsis
Key Takeaways
China has become only the second country after the United States to establish two-way laser communication between Earth and the moon, a milestone achieved by a team led by the Chinese Academy of Sciences using telescopes in Yunnan province. However, the data rates recorded fall significantly short of those demonstrated by NASA more than a decade ago, raising questions among space experts about the performance gap.
The numbers behind the milestone
According to the Chinese Academy of Sciences, the experiment recorded a downlink speed of 100 megabits per second (Mbps) and an uplink speed of 1.25 Mbps. The signals were relayed through an experimental satellite currently orbiting the moon — one that reached lunar orbit following a launch mishap in 2024. The achievement makes China only the second nation to demonstrate bidirectional laser communication at lunar distances.
Why it matters — and where it falls short
The performance gap with NASA's benchmark is substantial. NASA's 2013 Lunar Laser Communications Demonstration achieved download speeds of 622 Mbps and upload speeds of 20 Mbps — roughly six times faster on downlink and 16 times faster on uplink than China's current results. That 2013 demonstration remains the reference standard for deep-space optical communications, and China's figures, while historic, sit well below it.
Expert reaction
Jonathan McDowell, a London-based space historian and former Harvard astronomer, acknowledged the significance of the feat while noting the disparity. 'It sounds like China has not yet reached the data rates the US can achieve,' he said, adding that he did not know what accounted for the gap. Yang Lei, a deep-space laser communications expert and head of the research team, highlighted the broader speed advantage of laser communications over conventional radio-frequency methods in an interview with state news agency Xinhua last week.
The competitive backdrop
Laser — or optical — communications are considered a critical enabler for future deep-space missions, offering far higher bandwidth than traditional microwave links with lower power requirements. Both NASA and China are investing in the technology as part of broader lunar and deep-space exploration programmes, including China's planned Chang'e-7 mission and the Queqiao-2 relay satellite infrastructure. The gap in demonstrated performance suggests China's optical communications hardware and ground-station infrastructure still require significant development to match US capabilities.
What's next
The Chinese Academy of Sciences has not publicly outlined a timeline for achieving higher data rates, and the reasons for the current performance ceiling remain unexplained by the research team. As both nations accelerate lunar programmes ahead of planned crewed missions later this decade, closing the laser communications gap will be a key technical benchmark to watch.