The presence of water on the lunar surface is essential for human survival and has therefore attracted great interest from the scientific community. A significant advance in this field has come from the Ningbo Institute of Materials Technology and Engineering (NIMTE), of the Chinese Academy of Sciences (CAS), where researcher Wang Junqiang has developed a new method for producing water on a large scale using the reaction between lunar regolith and the hydrogen present in the lunar soil itself.
Previous missions, such as Apollo and Chang’E-5, had already identified the presence of water on the Moon. However, lunar minerals contain an extremely low amount of water, ranging from 0.0001% to 0.02%, which makes extracting water a significant challenge. In search of a solution, Wang and his team used samples of lunar regolith brought back by the Chang’E-5 mission to find effective ways of generating water on the lunar surface. “We used samples of lunar regolith brought back by the Chang’E-5 mission in our study, trying to find a way to produce water on the Moon,” explained Wang.
The studies showed that by heating lunar regolith to temperatures above 1,200 K using concave mirrors, one gram of molten regolith could generate between 51 and 76 mg of water. “In other words, one ton of lunar regolith can produce more than 50 kg of water, which can meet the daily drinking water needs of 50 people a day,” said Wang Junqiang. This volume is equivalent to around one hundred 500 ml bottles, enough to meet the drinking water needs of 50 people for one day.
The research also revealed that lunar ilmenite (FeTiO3), one of the five main minerals found in lunar regolith, contains the largest amount of hydrogen implanted by the solar wind. The lattice structure of ilmenite features subnanometer tunnels that facilitate hydrogen storage. When heated, these minerals react with iron oxides to form elemental iron and release large quantities of water.
In situ experiments indicated that the process of water formation occurs more efficiently at high temperatures. Initially, the formation of water in the lunar regolith was observed when the temperature exceeded 1,000 degrees Celsius, at which point the lunar soil melts and the water generated by the reaction is released as steam. In addition, it was discovered that the temperature at which water is formed could be reduced from 800 degrees Celsius to 200 degrees Celsius, which makes it easier to adapt the conditions needed to produce water in different regions of the Moon.
These findings offer new prospects for lunar exploration and the construction of future research stations on the Moon. The water produced could be used both for human consumption and for irrigating plants. In addition, it could be broken down electrochemically into hydrogen and oxygen, providing hydrogen for energy and oxygen for respiration. Understanding and harnessing the water content of lunar regolith is a crucial step towards ensuring human survival on long-duration space missions.
Chang’E-5, which returned to Earth in December 2020, brought with it 1,731 grams of lunar samples, mainly composed of rocks and soil. These materials continue to be a valuable source of knowledge, paving the way for new discoveries and advances in space exploration.
Results of the study were published in The Innovation.
