In an extraordinary leap for space exploration, China has made history by conducting the first daylight laser-ranging measurement from Earth to the moon.

This groundbreaking achievement was realized by researchers at the Yunnan Observatories, part of the prestigious Chinese Academy of Sciences (CAS). Using an upgraded 1.2-meter (3.9 feet) telescope equipped with an advanced infrared lunar laser ranging system, they targeted a tiny laser retroreflector on the Tiandu 1 satellite orbiting our celestial neighbor.

Laser ranging over the vast expanse of 186,000 miles (300,000 kilometers) is no small feat. It involves sending a powerful, precisely focused laser beam to strike a diminutive corner retroreflector, which sends the pulse straight back to its origin. The return signal, now a challenging task during the day, must be captured by ultra-sensitive telescopic detectors amidst overwhelming background "noise" caused by sunlight.

Through this technique, scientists accurately determine the time it takes for the laser signal to make the round trip, unlocking the ability to measure the moon’s distance with remarkable precision. Notably, similar laser retroreflectors were deployed during the historic Apollo missions.

This innovative daytime test not only broadens the opportunities for lunar observations but also holds significant promise for ambitious deep-space missions, particularly the China-led International Lunar Research Station (ILRS).

The Tiandu 1 satellite, launched in March 2024, is part of a duo of small satellites, alongside the Queqiao 2 lunar relay satellite, which has been pivotal for communications during the successful Chang'e 6 lunar mission.

With this technological triumph, China continues to assert its position at the forefront of space exploration, paving the way for future lunar and beyond missions.