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China has achieved a world first in space navigation by successfully firing a laser beam at a moon-bound satellite in broad daylight. Scientists at the Deep Space Exploration Laboratory in Hefei managed to strike the Tiandu-1 satellite, orbiting 130,000 kilometers from Earth, and record its distance with centimeter-level accuracy.
The experiment, carried out this week, marks the first time laser ranging has been achieved to a lunar spacecraft under sunny skies. Laser ranging works by sending short pulses of light to a target and measuring the time it takes for them to bounce back.
Until now, these tests were typically done at night, when faint return signals could be detected more easily without interference from sunlight. China’s team overcame this problem by using specialized filters and highly accurate timing equipment.
Their system was able to detect returning signals despite the overwhelming brightness of daytime conditions.
The Tiandu-1 satellite, launched in January, sits about a third of the way between Earth and the Moon. Tracking an object at that distance is difficult because of its speed and size. Researchers described the challenge as similar to hitting a moving hair from several kilometers away.
Still, their instruments recorded precise readings from laser pulses lasting only a few billionths of a second. Daytime tracking has clear benefits. It allows continuous monitoring of spacecraft without waiting for nightfall.
This capability is vital for China’s upcoming lunar missions, which include landing astronauts on the Moon by 2030 and building a joint base with Russia by 2035. It will also support their Queqiao relay satellites, designed to maintain constant communication with rovers and landers on the lunar surface.
The technology builds on earlier methods developed during the Apollo missions, when American astronauts placed retroreflectors on the Moon.
These are still used to measure its orbit, but China’s test shows how modern tools can work on spacecraft traveling through cislunar space in real time. Beyond the Moon, such technology could also improve navigation for Mars missions and asteroid probes.
Accurate distance measurements help map gravitational fields and predict spacecraft paths. With an estimated 100,000 satellites expected in low Earth orbit in the coming years, better ranging systems may also help reduce the risk of collisions.
For astronomers and engineers, the test highlights how small improvements in technology can make a major difference in managing space traffic and planning interplanetary travel.
China’s success in daytime laser ranging represents a new step in building safer and more reliable navigation systems for future exploration.
