An international team of researchers has made significant breakthroughs analyzing lunar soil samples returned by China’s Chang’e-5 and Chang’e-6 missions. Published in Science Advances, the study sheds light on the evolutionary history of organic compounds within the solar system.
Led by the Chinese Academy of Sciences in collaboration with the University of New Mexico, the researchers systematically identified multiple nitrogen-rich organic molecules embedded in lunar soil grains for the first time. These discoveries indicate that the Moon preserves a record of organic material delivered by asteroids and comets, while also retaining evidence of how impacts and solar irradiation modified these compounds over time.
In the early solar system, asteroids and comets acted as carriers, transporting essential elements like carbon and nitrogen to planetary bodies. Unlike Earth, where geological processes have erased much of this history, the Moon serves as a natural archive, maintaining this ancient chemical information.
Using advanced microscopic and spectroscopic methods, the team characterized the chemical bonds and isotopic compositions of the organic matter. They found that the isotopic signatures of lunar organics are lighter compared to those typically observed in asteroid samples. This suggests that extraterrestrial impacts caused decomposition and migration of organic materials, which subsequently condensed onto mineral surfaces, forming novel structures.
In a significant development, the study also detected solar wind implantation signatures within the lunar organic matter for the first time. Variations in hydrogen isotopes near the surfaces of grains indicate prolonged exposure to solar wind irradiation. Hao Jialong, the study’s corresponding author, emphasized that these isotopic “fingerprints” effectively exclude contamination from Earth.
This research establishes a robust analytical foundation for upcoming missions such as Tianwen-2 and provides fresh insights into the evolution and delivery of small-body materials throughout the early solar system.
