Schematic diagram of high-speed hydrogen ions injected from the sun’s surface into the moon’s surface and deposited on lunar soil particles Credit: Professor Lin Yangting’s team
Recently, much attention has been focused on the abundance, distribution, and origin of water on the moon’s surface as an important part of future space exploration.
A research team made up of members from the National Institute of Atmospheric Sciences and the Institute of Geology and Geophysics, both of which are part of the Chinese Academy of Sciences, discovered that the grain stems of the soil samples collected is the Chang’e-5 project has high standards. of hydrogen and a low ratio of deuterium to hydrogen, consistent with the theory that the moon’s water came from the solar atmosphere.
The findings were published in Bulletin of the National Academy of Sciences.
The researchers made simulations of hydrogen storage in lunar soil at different temperatures. They found that water from the SW can be stored well in the middle and upper regions of the lunar surface. “Moon soil may contain more water than the Chang’e-5 samples,” said IGG Professor Lin Yangting, co-author of the study.
Previous studies have shown that water (OH/H2O) in the lunar surface varies with latitude and time of day (up to 200 ppm). Such a marked change indicates an accelerated rate of decay from the lunar surface.
Unlike the six Apollo and three Luna missions, which all landed at low altitudes (8.97°S—26.13°N), the Chang’e-5 mission returned soil samples from space of middle latitude (43.06°N). In addition, Chang’e-5 samples were collected from the youngest known lunar basalts (2.0 Ga) and dry basaltic basement. Therefore, the Chang’e-5 samples are key to addressing the spatio-temporal distribution and retention of SW-absorbed water in the lunar regolith.
With 17 soil grains returned by the Chang’e-5 mission, researchers took deep NanoSIMS measurements of hydrogen abundance and deuterium/hydrogen ratios.
The results showed that most of the grain rims (topmost ~ 100 nm) showed high levels of hydrogen (1,116—2,516 ppm) with a very low value of δD (-908 ‰ to -992 ‰), which means the origin of SW. Based on the grain size distribution of lunar soil and hydrogen, the amount of water extracted from the SW is estimated to be 46 ppm for Chang’e-5 lunar soil, according to the remote sensing results.
Heating experiments with grain fractions showed that hydrogen embedded in SW can be stored after burial. Using this data along with previous data, the researchers modeled the dynamic balance between the absorption and release of SW-hydrogen from the lunar soil, revealing that temperature (latitude) plays an important role in the absorption and release of SW-hydrogen. hydrogen migration. in the soil of the moon.
Using this model, they predicted very high concentrations of hydrogen in grain bins in polar regions. Professor Lin said: “This discovery is very important for the future use of water resources on the moon. “Also, by sorting the particles and heating, it is easier to use and use the water in the lunar soil.”
Reference: “Abundance of water from the solar wind on lunar soil from mid-latitude” by Yuchen Xu, Heng-Ci Tian, Chi Zhang, Marc Chaussidon, Yangting Lin, Jialong Hao, Ruiying Li, Lixin Gu, Wei Yang, Liying Huang, Jun Du, Yazhou Yang, Yang Liu, Huaiyu He, Yongliao Zou, Xianhua Li and Fuyuan Wu, 12 December 2022, Bulletin of the National Academy of Sciences.
DOI: 10.1073/pnas.2214395119
