Life on the Moon still looks like science fiction, but American laboratories and agencies are already seriously working on creating lunar bases. The main problem is extreme temperatures: during the day on the Moon it is about 127 degrees Celsius, and at night the thermometer drops to minus 173. In addition, resources are limited, and long missions inevitably leave trash behind. Researchers Alexander Wei and Jacob Staker from Purdue University (USA) proposed solutions to these problems. They are developing aerogels - ultralight porous materials that are 99% empty space and therefore conduct almost no heat. On Earth, such materials are used to insulate spacecraft, buildings and electric vehicles.
The scientists propose making aerogels from cellulose - a natural fiber that can be obtained from paper or cardboard waste - and a lunar soil simulant (regolith). Regolith is a mixture of minerals close in composition to real lunar dust. The results of the work were published in the journal ACS Sustainable Chemistry & Engineering.
First, the components, together with water, are ground in a ball mill with heavy ceramic balls. In this process, the minerals help break the cellulose down into ultrathin threads less than a micron in diameter. Such fibers, called nanofibrillated cellulose, increase the surface area and strength of the future aerogel so that it does not crumble. The mixture is then frozen and dried. Currently, the final stage is carried out using supercritical drying - an industrial method in which the material does not shrink. However, this method requires a lot of energy and carbon dioxide, which is not available on the Moon. Therefore, the authors are studying lyophilization, or freeze-drying: the mixture is frozen and placed in a vacuum, where the ice turns into vapor, bypassing the liquid stage. According to Wei, on the Moon there is natural vacuum and nighttime cold for this, and water can be captured and reused.
The researchers produced aerogels with different ratios of regolith and cellulose. It turned out that the less cellulose, the better the thermal insulation and the lower the density. But as the cellulose content increases, the strength improves. Thus, a compromise has to be found between insulation and mechanical durability. The goal is to select a composition that, with minimal resources, provides enough warmth and strength.
The authors emphasize: their work is laboratory testing, not a ready-made recipe for construction. Testing of the technology in real lunar conditions still lies ahead.