China's Tiandu satellite pulls off laser ranging in Earth-moon space under daylight

From Saturday to Sunday, China's Tiandu-1 communication and navigation technology experiment satellite successfully conducted a laser ranging technology test in the Earth-moon space under strong daylight interference conditions, marking a world first in overcoming the time restriction of satellite laser ranging in Earth-Moon space only being performed at night, signifying a new technological advancement in the field of precision measurement in deep space orbits, Global Times learned from the satellite developer China's Deep Space Exploration Lab (DSEL) on Monday.

Due to the vast scale of Earth-moon space and the extremely high speed of satellite motion, conducting laser ranging on satellites in such an environment is akin to aiming at a single hair (sub-millimeter target) from 10,000 meters away while performing precise tracking and signal acquisition, said DSEL in a statement it provided to the Global Times on Sunday. 

Satellite laser ranging in Earth-moon space was limited to nighttime conditions without light interference, restricting observation periods and resulting in insufficient frequency of orbital dynamic data collection. The successful execution of this laser ranging test under daylight interference conditions significantly expands the observation window for this technology, providing a practical engineering foundation for its widespread application, DSEL said. 

This achievement will strongly support the validation and implementation of major deep space exploration missions, such as the International Lunar Research Station, it added. 

As the first satellites ever developed by DSEL, the Tiandu-1 and -2 satellites were sent into space together with the Queqiao-2 relay satellite on March 20, 2024. They entered their target circumlunar orbits on March 29 and separated on April 3, according to the Xinhua News Agency. They have conducted a series of technological experiments for lunar communication and navigation.