Researchers have completed a laser communications test between Earth and the moon, successfully verifying two-way high-speed laser link capabilities in orbit, the Technology and Engineering Centre for Space Utilisation (CSU) of the Chinese Academy of Sciences says.
After more than a year of in-orbit testing, the team established a two-way laser communication link across a distance of more than 400 000km, marking the expansion of China’s space laser communications from near-Earth orbit to deep space.
Compared with traditional microwave communications, laser communications offer faster speeds, greater bandwidth, stronger security and more compact hardware. However, enabling laser communications across the Earth-moon distance required overcoming three major challenges: beam alignment, signal weakness and transmission speed.
“Earth-moon communication is like threading a needle from a thousand miles away,” said Yang Lei, a researcher at the CSU and head of the laser communication test team, on Friday.
Given the extreme distance, minor satellite wobbles or ground atmospheric turbulence can cause laser beams to drift. A tiny angular deviation could translate into a kilometre-scale miss at the moon’s distance.
The team developed an innovative acquisition and tracking scheme that integrates corrections for orbital, atmospheric and optical propagation delays, enabling ground and spaceborne equipment to maintain precise alignment while in motion.
After travelling 400 000km back to Earth, the laser signal became so faint that ground telescopes received only a few photons at a time. Moonlight, starlight and urban lighting added further interference — akin to hearing the sound of a falling pin in a bustling market, the CSU said.
The researchers developed high-speed superconducting single-photon detection technology and high-sensitivity algorithms to extract valid communication signals from background noise.
To tackle the speed bottleneck, the team developed high-bandwidth signal processing technology and adopted special coding schemes to counter noise. The test achieved two-way communication rates of 1.25Mbps uplink and 100Mbps downlink.
With manned lunar landings and lunar research station construction on the horizon, future lunar exploration would generate massive volumes of observation images and scientific data that traditional communications bandwidth could no longer support. This Earth-moon laser “information highway” would provide a new high-speed data transmission route for upcoming lunar missions, the CSU said.
- Researchers have completed a laser communications test between Earth and the moon, successfully verifying two-way high-speed laser link capabilities in orbit, the Technology and Engineering Centre for Space Utilisation (CSU) of the Chinese Academy of Sciences says.
- After more than a year of in-orbit testing, the team established a two-way laser communication link across a distance of more than 400 000km, marking the expansion of China’s space laser communications from near-Earth orbit to deep space.
- Compared with traditional microwave communications, laser communications offer faster speeds, greater bandwidth, stronger security and more compact hardware.
- However, enabling laser communications across the Earth-moon distance required overcoming three major challenges: beam alignment, signal weakness and transmission speed.
- “Earth-moon communication is like threading a needle from a thousand miles away,” said Yang Lei, a researcher at the CSU and head of the laser communication test team, on Friday.
