Designing for space can take inspiration from Earth-based technologies, of course, but there are extra considerations to take into account when coming up with solutions to work on a space station. For example, antimicrobial technology needs to be safe for a confined environment where astronauts use a water recycling system.
“Antimicrobial coatings on Earth often make use of silver, but we want to do without it here,” Malgorzata explained. “The issue is that in the confined environment of a spacecraft, prolonged exposure to silver could have negative health effects for astronauts — we don’t want a heavy metal buildup in the onboard water, for instance.” That’s because being exposed to too much silver in a water supply can lead to health problems like skin and eye irritation, which wouldn’t be good for astronauts.
Instead of silver, the researchers are trying out titanium oxide as an alternative. This compound has the advantage of being stable over time, so it shouldn’t break down too quickly. But before it is used across the space station, the researchers need to check what happens when it degrades, because they want to make sure that any byproducts from oxidizing the bacteria aren’t harmful. Another requirement is that the coating needs to be used on all sorts of materials, like glass and metal and fabrics. The layer needs to be thin enough that it doesn’t interfere with material properties, such as by making fabric less flexible. To achieve this, the coatings being tested are extremely thin, at millionths of a millimeter in thickness.