Moon Habitats May Use Layered Mylar to Block Extreme Heat

Living on the Moon—whether as a trained astronaut or an ordinary civilian—could become common in the future. Yet making that possible is far more difficult than it sounds. Scientists and engineers must find new ways to protect people from the Moon's harsh environment, which is very different from Earth's mild, livable temperatures. One of the most important tasks is keeping humans alive, and that includes controlling temperature inside habitats. The challenge is to maintain that temperature control while using materials flexible enough to handle movement, handling, and repeated compression and expansion.

A team of researchers from the University of Pennsylvania may help future human missions to the Moon. The team introduced a new design for insulation that also provides the flexibility needed for long-term use. Their findings were published in ACS Applied Materials & Interfaces. The main goal was to fill a gap in knowledge about how to make and use materials that can keep humans alive while surviving the long-term wear and tear of the lunar environment, especially extreme temperature changes.

To address this problem, the researchers created layered Mylar sheets designed to withstand vacuum conditions while remaining flexible enough for long-term use. They tested Mylar thicknesses of 2.5 micrometers (µm), 5 µm, and 12.5 µm. They also tested layer densities ranging from 80 to 400 layers per millimeter. The 2.5 µm, 5 µm, and 12.5 µm sheets were stacked at 400, 200, and 80 layers, respectively. Each layered stack was then put through a series of demanding tests involving vacuum conditions and a wide range of temperatures. These tests included pressures equal to 200 pounds of pressure on an area the size of a fingertip.

In the end, the researchers were surprised to find that they preferred the medium (5 µm) and thicker (12.5 µm) layered stacks. They had expected the thinner (2.5 µm) stack to perform best. They discovered that the thinner layers allowed certain microparticles in the sheets to spread heat more easily, which meant the material was not a very good insulator. By contrast, the medium and thicker layers had microparticles that were less in contact with one another, which allowed for greater insulation. The researchers also found that the stacks were more resilient than they had expected.

“You could use these stacks to insulate a lunar habitation, but astronauts will inevitably have little accidents where they bump into them,” said Dr. Igor Bargatin, Associate Professor of Mechanical Engineering and Applied Mechanics at UPenn and a co-author on the study. “When we’re talking about long-term habitation on the Moon, it’s really important to have tough materials that can last long enough.”