Context images and water content at the Chang’e-5 landing site. [IMAGE: LIN HONGLEI]

A joint research team led by Professors Lin Yangting and Lin Honglei from the Institute of Geology and Geophysics of the Chinese Academy of Sciences (IGGCAS) observed water signals in reflectance spectral data from the lunar surface acquired by the Chang’e-5 lander, providing the first evidence of in-situ detection of water on the Moon.

The study was published in Science Advances on January 7, 2022.

The lunar mineralogical spectrometer (LMS) onboard the Chang’e-5 spacecraft lander performed spectral reflectance measurements of the regolith and of a rock, thereby providing the unprecedented opportunity to detect lunar surface water.

The researchers used a thermal correction model to correct the LMS spectra. Following this correction, the undoubted spectral absorptions at 2.85 μm were observed at the Chang’e-5 landing site.

The quantitative spectral analysis indicates that the lunar soil at the landing site contains less than 120 ppm of water, which is mostly attributed to solar wind implantation. This is consistent with the preliminary analysis of the returned Chang’e-5 samples.

In contrast, a light and vesicular rock that was also analyzed exhibited much stronger absorption at 2.85 μm, corresponding to an estimated ~180 ppm of water, thus suggesting an additional water source from the lunar interior.

This discovery is consistent with the prolonged volcanic eruptions in the Procellarum KREEP (potassium, rare earth elements, phosphorus) Terrain region, and also provides vital geological context for the analysis of the returned Chang’e-5 samples.

Source: Institute of Geology and Geophysics,

Chinese Academy of Sciences