Future lunar bases will be able to obtain oxygen directly from lunar soil without having to transport it from Earth. Such was the conclusion of a study by engineers from the University of Manchester and the European Space Agency (ESA) based on the tests of an innovative robotic system for the mining, transportation and treatment of regolith.
Oxygen is one of the most important resources for lunar exploration. It is needed not only for astronauts to breathe but also as a component of rocket fuel. Nearly 45% of lunar soil mass is comprised of oxygen chemically bound to minerals. However, prior to its extraction, the regolith must be excavated, transported to a processing facility and separated into the smallest particles measuring less than 100 microns, which are best suited for most oxygen production technologies.
It was this process that the researchers tested using the MoLES3 system. The system consists of a mobile rover with a robotic arm and scoop, as well as a stationary soil sorting unit. The rover would select a digging location on its own with a depth camera, collect some 300 grams of soil per cycle, deliver it to the sorting unit and unload it via a special flexible adapter.
The tests were conducted at the LUNA test site in Germany, where a lunar soil simulator is used. Over 2.5 hours, the system completed 37 operation cycles, processing 10.8 kilograms of regolith. As a result, it produced 2.1 kilograms of fine fraction suitable for subsequent oxygen extraction.
The study showed that sorting was not the greatest challenge. The vibration unit’s efficiency reached 93%: it managed to separate particles of the desired size almost completely. The biggest losses occurred during the transfer of soil from the rover to the sorter: some 7% of the material spilled or remained in the hopper. The scientists believe that the productivity of future lunar complexes will be improved significantly when these losses are eliminated.
The researchers also found that sorting accounted for only about 11% of the system’s total energy consumption. The bulk of the energy was spent on the rover’s movement and the operation of the robotic arm.
Needless to say, it is important to keep in mind that the tests were conducted under terrestrial conditions. The equipment will perform differently on the Moon, where gravity is six times weaker. Nevertheless, this is the first study to provide real quantitative data on the entire lunar soil preparation chain, from extraction to sorting. These results could form the basis for autonomous robotic systems that will provide future lunar bases with oxygen, water and construction materials.
