NASA's Artemis mission to Moon has been delayed by NASA, but this doesn't mean that a return to the Moon will not be possible. All space agencies have their eyes on the rocky satellite. They will need in-situ resources, no matter who they are, regardless of how they get there.
Water and oxygen are the most important resources astronauts will require on the Moon. Engineers and scientists are working together to find out how to boil Moon rocks in order to extract vital oxygen and water. Their results were presented at the Europlanet Science Congress in 2021.
The experiments were led by Professor Michle Lavagna, Politecnico Milano. The work was done by a consortium of agencies and companies, including the ESA, and the Italian Space Agency. Lavagna and other scientists presented a demonstration of their work at EPSC2921.
Moonrock refers to lunar regolith, which is the dust layer that covers the Moon. This same layer caused confusion for Apollo astronauts when it found its way into their lunar module and blocked mechanisms. Space agencies continue to work on ways to reduce the dust. However, the same dust can also be a vital resource.
Apollo 17 astronaut digs into the lunar regolith in order to study the mechanical behavior of moon dust. Credit: NASA
Because oxygen reacts readily with other elements, particularly group one elements, there is a lot of oxygen in lunar regolith. The lunar soil is rich with oxides, including silicon dioxide, iron oxide and magnesium oxide. The ESA estimates that about half of lunar soil contains iron and silicon dioxide. About 26% of these compounds are oxygen. The trick is to get the oxygen out.
Lavagna demonstrated two-step processes that are used regularly in industrial applications on Earth. The simulated lunar regolith first gets vaporized with hydrogen and methane, then it is washed with hydrogen. The minerals are heated to 1,000 Celsius (1800 F) by a furnace, which transforms them from solid to gas. The minerals are able to skip the liquid phase and make the whole process much simpler.
The gases and residual methane are then sent to a catalytic convertor, and finally a condenser that separates water. Hydrolysis then separates oxygen and the system recycles hydrogen and methane wastes.
For many years, engineers and scientists have struggled to extract in-situ resources from the Moon. To extract oxygen, one method is molten salt electrolysis. This method can be adapted from mining and produces useful metal alloys using lunar regolith.
Lavagna says that one of the most important features of this newer process is its almost hands-off approach.
Professor Lavagna said that our experiments have shown that the rig can be scaled and can operate in a nearly self-sustaining closed loop without human intervention.
This video shows how water is extracted from the process. Credit: Politecnico Milano, CC BY-NC-CD
In anticipation of a fight test, the team is still optimizing the process. They are focusing on the furnace temperature, frequency and length of washing, gas mixture ratios and soil batch sizes. They have discovered that small soil batches produce maximum yields when they are combined with high temperatures and prolonged washing phases.
As a byproduct, silica is produced. It also produces metals, which require further processing before they can be used in-situ.
Lavagna stated that it is essential to have efficient water and oxygen production facilities at the site. This will allow human exploration as well as high-quality science on the Moon. This has allowed us to understand each step of the process better through laboratory experiments. This isn't the end of the story. But it is a good place to start.
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