In an unprecedented scientific achievement, a team of Chinese scientists succeeded in shooting a laser beam from Earth to the Moon and measuring the distance between them in broad daylight, overcoming one of the most complex obstacles in space physics, which is the enormous challenges that sunlight poses to such experiments.
This extraordinary event, which took place using the Tiandou-1 satellite, opens a new chapter in lunar navigation technology, and paves the way for a more accurate future in spaceflight between the Earth and the Moon.
Experts describe this step as a milestone in space exploration technology, which may redraw the limits of human capabilities in navigation between Earth and the moon.
According to the official Chinese news agency Xinhua, scientists carried out the experiment using the Tiandu-1 satellite and an advanced near-infrared laser ranging system. Although measuring the distance between the Earth and the Moon is not new, doing so in broad daylight is considered a scientific breakthrough, as all previous attempts were conducted at night to avoid intense solar interference that disrupts laser signals.
From night to day: breaking the solar barrier
The experiment was carried out on April 27, 2025, as part of an ambitious project led by Chinese space researchers within the lunar exploration program. The biggest challenge for the team was to overcome what is known as “optical noise” resulting from sunlight spreading in the atmosphere, which causes interference with laser signals returning from space.
Typically, for this type of measurement, scientists fire laser pulses from Earth at a celestial body — such as the Moon or a satellite — equipped with optical reflectors. After the rays are reflected back to the Earth, the time taken by the flight is calculated to determine the distance very accurately. But during the day, all observing attempts are drowned out by the sun’s harsh rays, making measurement nearly impossible.
For this reason, China’s success in implementing daylight measurement is a revolutionary achievement in the history of space optics. Chinese scientists have developed a highly sensitive laser system capable of distinguishing the precise signal amidst solar noise, through the use of advanced optical filters and highly precise sensors.
The role of the “Tianduo-1” satellite
The Tiandou-1 satellite, which was launched in March 2024, played the pivotal role in this historic experiment. This satellite was designed as a platform for testing communications and navigation technologies between Earth and the Moon, within what is known as the “Deep Space Exploration Laboratory” project.
The project aims to establish an integrated communications and navigation network between Earth and the Moon, which will be used to support future lunar missions, including landing operations and building permanent research stations.
“Tiando-1” works in coordination with another satellite, “Tiando-2”, to form a satellite constellation that acts as a permanent link between planet Earth and lunar missions. This technical cooperation provided an ideal environment for conducting the experiment, which demonstrated the possibility of carrying out accurate ranging operations even in the most difficult lighting conditions, according to “dailygalaxy.”
A step that paves the way for a new era of lunar navigation
This scientific breakthrough represents a qualitative leap in the field of space navigation, as it will allow continuous measurements to be made throughout the day instead of being limited to the night hours only.
This means that scientists will be able to collect more accurate and abundant data about the movement of satellites and lunar rovers, opening new horizons for mission planning and deep space exploration.
It is also expected that this achievement will support the International Lunar Research Station (ILRS) in the future, which is a joint project between China and Russia that is planned to be established by 2035, as a permanent base for scientific research on the surface of the moon.
Laser ranging systems will serve as a “precise compass” to guide spacecraft, lunar robots and landers, and coordinate their movements with extreme precision in the complex lunar environment.
The technology behind the achievement
The laser system used is based on near-infrared rays, which are better able to penetrate optical interference than visible wavelengths.
The system was equipped with highly sensitive receivers and advanced software to filter signals, which made it possible to accurately track the laser bounce from the moon’s surface at a distance of more than 130,000 kilometers — in broad daylight.
Chinese experts point out that this technology will contribute to improving the accuracy of space navigation systems such as the Chinese Beidou system, and help lunar missions determine their locations with almost centimeter accuracy. It can also be used in the future to draw accurate topographic maps of the moon’s surface and study its orbit relative to the Earth.
Wider impact on the space race
As global competition in space exploration accelerates, this achievement reinforces China’s position as a major power in the scientific and technical field.
While the United States seeks, through the “Artemis” program, to return humans to the moon, China is developing its infrastructure in preparation for the stage of permanent settlement on the moon’s surface, through manned research stations and smart robots.
Observers believe that the ability to perform daytime laser measurement gives China a strategic advantage in managing future missions, as it allows accurate monitoring of vehicle paths at any time of the day, without relying on darkness or ideal weather conditions.
A new beginning for the era of satellite communications
This achievement represents not only a successful technical experiment, but a symbolic step towards a new generation of space exploration based on the integration of optical precision, artificial intelligence, and laser navigation.
While laser measurements used to be limited to specific circumstances, China has now opened the door to non-stop exploration, with satellites and ground-based observatories working in harmony around the clock.
While scientists describe the experiment as a “scientific leap,” others see it as evidence of China’s accelerating ambition to build an integrated space infrastructure extending from the Earth to the moon and perhaps beyond.
From a single laser beam fired in broad daylight, to a dream of establishing a scientific base on the moon, China seems to be moving steadily towards redefining the limits of what is possible in space.
