In a historic milestone for space exploration, China’s Tiandu-1 satellite has achieved the world’s first daylight Earth-Moon laser ranging, a groundbreaking feat that overcomes the challenges of solar interference. Conducted by the Deep Space Exploration Laboratory (DSEL) and Yunnan Observatories, this experiment marks a significant leap in deep-space navigation and strengthens China’s position in the global space race.
A Breakthrough in Deep-Space Technology
The Tiandu-1 satellite, launched on March 20, 2024, successfully reflected a laser beam from a 1.2-meter telescope equipped with a near-infrared lunar laser ranging system, located approximately 130,000 kilometers from Earth. This test, performed under strong daylight conditions on April 26-27, 2025, is the first of its kind, as previous Earth-Moon laser ranging was limited to nighttime due to solar noise. Researcher Li Yuqiang from Yunnan Observatories hailed the achievement as a “critical advancement in deep-space orbit measurement.”
Why Daylight Laser Ranging Matters
Laser ranging is a precise method for measuring distances to satellites by sending laser pulses and calculating the time it takes for them to return. This technology is vital for tracking satellites in Earth-Moon space, supporting lunar landers, rovers, and future crewed missions. By enabling daylight operations, China has expanded observation windows, enhancing data collection for its lunar exploration programs, including the Queqiao-2 relay constellation and the International Lunar Research Station, a joint project with Russia.
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Tiandu-1: A Key Player in China’s Lunar Ambitions
Tiandu-1, alongside Tiandu-2 and Queqiao-2, is part of China’s effort to build a robust Earth-Moon communication and navigation network. Launched in March 2024, these satellites are testing technologies for future lunar missions expected before 2030. The successful daylight laser ranging experiment demonstrates China’s ability to overcome technical barriers, paving the way for more accurate spacecraft positioning and navigation in deep space.
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Global Implications and Future Prospects
This achievement has drawn global attention, with experts noting its potential to redefine deep-space exploration. The ability to perform laser ranging in daylight could enhance the precision of lunar missions and support long-term human presence on the Moon, particularly at the lunar south pole. As China advances its space program, this milestone underscores its growing influence in the space technology race, challenging other spacefaring nations.