The distribution, time-varying characteristics, and sources of lunar water remain controversial. This study presents Chang'E-5 in-situ spectral observations of lunar water under Earth's magnetosphere shielding and relatively high temperatures. Results show a mean hydroxyl content of 28.5 ppm in lunar soils at the Chang'E-5 landing site, consistent with remote sensing and telescopic data. Analysis of returned samples suggests a weak contribution from solar wind implantation, while hydroxyl-containing apatite is identified as a potential significant source of the observed hydroxyl in this young mare region.

Jianjun Liu, Bin Liu, Xin Ren, Chunlai Li, Rong Shu, Lin Guo, Songzheng Yu, Qin Zhou, Dawei Liu, Xingguo Zeng, Xingye Gao, Guangliang Zhang, Wei Yan, Hongbo Zhang, Lihui Jia, Shifeng Jin, Chunhua Xu, Xiangjin Deng, Jianfeng Xie, Jianfeng Yang, Changning Huang, Wei Zuo, Yan Su, Weibin Wen, Ziyuan Ouyang