Chang’e-6, a robot that returned from the Moon in 2024, brought samples from the South Pole–Aitken impact basin on the Moon’s far side. Testing the sample, Sen Hu and colleagues say the water content of the samples was lower than previous samples from the near side of the Moon.
They estimate that the water abundance for the mantle is 1–1.5 micrograms per gram, which is on the dry end of measurements made on the lunar nearside (1–200 micrograms per gram). The authors suggest the difference in the distribution of water in the Moon’s mantle could potentially represent a hemispheric division, which mirrors differences in surface features.
The authors conclude that their findings are important for estimating the total water abundance on the Moon and provide constraints for the giant impact hypothesis for the formation of the Moon and subsequent lunar evolution.
