Chinese scientists have discovered a method to obtain water from lunar soil after studying the soil samples brought back by China's Chang'e-5 lunar probe, an important discovery for the design of a future lunar research station.
Lunar soil samples retrieved by China's Chang'e-5 probe, Institute of Physics, Chinese Academy of Sciences, Beijing, July 24, 2024. /CFP
A team of researchers from the Chinese Academy of Sciences found that minerals in lunar soil contain a large amount of hydrogen after being radiated by solar wind for hundreds of millions of years. When heated, the hydrogen undergoes a redox reaction with the iron oxide in the minerals and thus produces water and zero-valent iron. At 1,000 degrees Celsius, the soil melts and releases water vapor into the air.
The team, after repeated experiments and analysis, has confirmed that one gram of lunar soil could produce 51-76 milligrams of water. Researchers further concluded that one tonne of lunar soil could churn out 51-76 kilograms of water, or over 100 bottles of water each containing 500 milliliters, and thus could meet 50 people's daily drinking water demand.
Upon further comparison between different minerals, the team discovered the ilmenite could have more potential as it could make large amounts of water and zero-valent iron simultaneously.
Based on the research, the team went further to propose a method of water resource development on the moon: to focus the sunlight through a concave mirror or Fresnel lens, heat the lunar soil to melt, condense the water vapor into liquid water and finally store it in a water tank.
According to the plan, the water then could be electrolyzed into oxygen and hydrogen, which could be used for human beings' respiration and energy use, respectively. The iron could be turned into magnetic materials for electronic devices as well as construction materials. The melted lunar soil could be made into bricks for the construction of a lunar base.
Researchers believe that the method will provide an important basis for the design of future lunar research stations and space stations. The team also plans to send devices during future lunar missions to validate their idea.
Water is a key resource to ensure human beings' survival when building a lunar research station and conducting future interstellar travel on the moon. Therefore, exploring water resources is one of the top priorities for lunar exploration.
Scientists have previously focused on the natural water resources on the moon.
Previous research shows that a variety of lunar soil minerals contain a small amount of water, only between 0.0001 percent and 0.02 percent of the lunar soil's weight, which is extremely rare and difficult to extract on the moon. By comparison, under the new method by the research team, the same amount of lunar soil is expected to put together 250 times the amount of water.
The Chang'e-5 probe, which returned to Earth on December 17, 2020, retrieved 1,731 grams of lunar samples.
(Cover: Chinese researchers doing scientific analysis of lunar samples. /CMG)