applications: Thermal insulation; with fibre reinforced silica aerogel insulation boards insulation thickness can be reduced by about 50% compared to conventional materials. This makes silica aerogel boards well suited for the retrofit of historic buildings or for the application in dense city areas. As other examples, aerogel has been added in granular form to skylights for this purpose. Georgia Institute of Technology's 2007 Solar Decathlon House project used an aerogel as an insulator in the semi-transparent roof. A chemical adsorber for cleaning up spills. Silica aerogels may be used for filtration; They have a high surface area, porosity, and are ultrahydrophobic. They may be used for the removal of heavy metals. This could be applied to wastewater treatment. As a daytime radiative cooling surface that is designed to be efficient in solar radiation and thermal emittance. Aerogels may be lower in cost and negative environmental impacts than other materials. A catalyst or a catalyst carrier. Silica aerogels can be used in imaging devices, optics, and light guides. Thickening agents in some paints and cosmetics. As components in energy absorbers. Laser targets for the United States National Ignition Facility (NIF). A material used in impedance matchers for transducers, speakers and range finders. According to Hindawi's Journal of Nanomaterials, aerogels are used for more flexible materials such as clothing and blankets: "Commercial manufacture of aerogel 'blankets' began around the year 2000, combining silica aerogel and fibrous reinforcement that turns the brittle aerogel into a durable, flexible material. The mechanical and thermal properties of the product may be varied based upon the choice of reinforcing fibers, the aerogel matrix and opacification additives included in the composite." Silica aerogel has been used to capture cosmic dust, also known as space dust. NASA used an aerogel to trap space dust particles aboard the Stardust spacecraft. These aerogel dust collectors have very low mass. The particles vaporize on impact with solids and pass through gases, but can be trapped in aerogels. NASA also used aerogel for thermal insulation for the Mars rovers. The US Navy evaluated use of aerogels in undergarments as passive thermal protection for divers. Similarly, aerogels have been used by NASA for insulating space suits. In particle physics as radiators in Cherenkov effect detectors, such as the ACC system of the Belle detector, used in the Belle experiment at KEKB. The suitability of aerogels is determined by their low index of refraction, filling