The cost of launching things into orbit is about ten thousand dollars per pound. It takes complex heavy equipment and fuel to get anything to orbit. This means that making payloads as light as possible is important. NASA has used a variety of techniques to reduce the weight that has to be thrown into orbit in order to be useful. They have launched inflatable systems into orbit that can be inflated to make light habitats. They have launched systems of light weight rods that can be reconfigured into complex structures. Now, NASA scientists have created a foldable fabric that has three capabilities that will be very useful in orbit.
Researchers at the Jet Propulsion Laboratory have spent two years working on a metallic fabric that is composed of interlocking stainless steel squares. In appearance, the new material looks like chain mail. It is not made by connecting lots of little piece of metal by hand but rather it is 3-D printed. The printer extrudes stainless steel as a continuous sheet with different properties of the top and the bottom. The top of the fabric consists of small squares that reflect heat and light well. On the bottom of the material, interlocking loops helps the fabric absorb heat. The material also acts as a very strong shield to protect astronauts and spacecraft from fragments of space junk in orbit.
NASA already has materials that individually have the properties of the new fabric, but the new material combines all three of these important capabilities into one package. Raul Polit Casillas is a system engineer at JPL who worked on the new fabric. He said, “We wanted to see if a structure could do something beyond being a static piece of material.”
NASA was able to combine these different properties into the new fabric employing what is being called 4-D printing. This new manufacturing technique uses a 3-D printer to create individual layers which are combined into one structure. Skyar Tibbits is the MIT researcher who coined the term “4-D printing”. He created materials which could change their shape or self-assemble using the new technique. With this manufacturing method, engineers could program a piece of metal that could unfold at a certain temperature or design a plastic that could respond to the environment by expanding or contracting.
Unlike a normal piece of metal, the new metal fabric can bend and fold easily while maintaining its strength. This property will make it useful on a spacecraft that is full of stiff materials and hard objects. NASA is just beginning to work with the 4-D printing system. Casillas hopes that his team will be able to create materials with even more advanced capabilities. They could develop fabrics that conduct electricity and heat as well as change their shape. He says that the point of his work is to “increase the science we can do per kilogram.”