A Groundbreaking Achievement in Space Exploration

In a remarkable scientific milestone, China has successfully performed the first-ever laser ranging measurement from Earth to the moon during broad daylight.

The Technology Behind the Achievement

Researchers at the Yunnan Observatories, part of the Chinese Academy of Sciences, employed an advanced infrared lunar laser ranging system. Utilizing a recently upgraded 1.2-meter telescope, they aimed a precise laser beam at a small retroreflector located on the Tiandu 1 satellite orbiting the moon.

The Challenge of Lunar Laser Ranging

Laser ranging across the vast expanse of space is no small feat. This process involves sending a high-powered laser beam over an astounding 186,000 miles (300,000 kilometers) to strike a tiny corner retroreflector. The reflector then sends the beam right back to its source, where the return signal is detected by ultra-sensitive instruments. Conducting this operation during the day poses an additional challenge due to significant background light interference from the sun.

Precision and Applications

Through meticulous timing of the returned signal, scientists can calculate the distance to the moon with unprecedented accuracy. This technique builds on past efforts, including those from the Apollo missions, which placed laser retroreflectors on the lunar surface.

Expanding Horizons for Future Missions

The successful daytime measurement opens new avenues for lunar observation, potentially benefiting future deep-space exploration initiatives. One such mission is the China-led International Lunar Research Station (ILRS), which aims to deepen our understanding of lunar science.

About Tiandu 1 and Its Role

Launched in March 2024, the Tiandu 1 satellite is one of two mini satellites that accompany the Queqiao 2 relay satellite. The Queqiao 2 has been crucial for communications, particularly during the Chang’e 6 mission, which successfully returned samples from the lunar far side a few months later.