Chinese Laser Fires Beyond Range Expectations

In a groundbreaking feat, Chinese scientists have achieved the world’s first daylight satellite laser ranging in Earth-Moon space.

The experiment, conducted between 26 and 27 April 2024, involved firing a near-infrared laser from Yunnan Observatories in southern China to the Tiandu-1 satellite, which orbits roughly 130 000 kilometres from Earth.

The laser successfully bounced off Tiandu-1’s retroreflector and was detected back on Earth, despite the challenge of solar background noise, which typically hampers such attempts in daylight.

This precision – the equivalent of hitting a single hair from 10 kilometres away – was made possible by an upgraded 1.2-metre telescope system at the Chinese Academy of Sciences facilities. Until now, laser ranging between Earth and lunar distances had only been feasible at night.

The success significantly enhances China’s capabilities in precise orbit tracking and deep-space navigation, laying vital groundwork for its planned lunar base, the International Lunar Research Station, which will be developed in partnership with Russia.

The process is a cornerstone of satellite positioning. While NASA has used similar methods, including on India’s Vikram and Japan’s SLIM landers, China’s daytime success covers a distance 1 000 times greater than previous orbital attempts.

This breakthrough removes a major limitation – sunlight interference – and paves the way for continuous, high-precision tracking, to support future lunar missions, crewed landings by 2030, and future Mars-bound laser communications.

China now plans to expand these daylight trials to longer distances and higher repetition rates, integrating them into routine deep-space operations.

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