Redox processes on the lunar surface: Current status and progress

The lunar regolith records signatures of material‒energy interactions with both the solar system and beyond. Traditional space weathering processes, based on laboratory analyses and remote-sensing data, emphasize a reduction-dominated paradigm in which nanophase metallic iron (np-Fe⁰) formation and spectral reddening are primarily driven by micrometeorite impacts and solar wind irradiation. However, emerging evidence of complex oxidation processes, including impact-generated magnetite, disproportionation reactions, and oxidation signatures potentially induced by Earth's magnetotail, challenges this conventional view. These conflicting evolutionary signatures indicate that existing models may fail to capture the full spectrum of oxidation and reduction pathways involved in lunar space weathering. Integrating laboratory analyses and remote-sensing data, we here construct a multi-scale redox dynamics framework that elucidates three critical reaction processes: vapor deposition, in situ reduction, and self-redox reactions. This framework reveals a spatiotemporal decoupling between globally sustained reduction and localized, episodic oxidation events. This review provides key constraints for understanding the complex lunar surface evolution mechanisms and long-term evolution of airless planetary bodies.