Aerogel

Aerogel is a silicon-based substance often called frozen smoke or blue smoke. It is composed of 99.8% air and is a stiff foam with a density of 3 mg per cm³, which makes it the world's lightest solid. With a highly dendritic-like structure, aerogel has extremely low thermal conductivity which gives it remarkable insulative properties. It has a melting point of 1,200° celsius. Its almost transparent nature makes it suitable for trapping dust particles, as it did aboard the Stardust spacecraft.

Aerogel is made by drying a gel composed of colloidal silica in an extreme environment. It is the result of coordinated research between NASA and Aspen Systems, Inc