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Aerogel is a broad term used to talk about an extraordinary group of materials that have been used since the 1960s in space travel, but are now finding uses across a whole range of industries. ‘Aerogel’ is not a specific mineral or material with a set chemical formula-rather, the term is used to encompass all materials with a specific geometrical structure. This structure is an extremely porous, solid foam, with high connectivity between branched structures of a few nanometres across.
Though aerogel is technically a foam, it can take many different shapes and forms. The majority of aerogel is composed of silica, but carbon, iron oxide, organic polymers, semiconductor nanostructures, gold and copper can also form aerogel. However, within the aerogel structure, very little is solid material, with up to 99.8% of the structure consisting of nothing but air. This unique composition gives aerogel an almost ghostly appearance; hence it is often referred to as ‘frozen smoke’.
Applications of Aerogel
As aerogel has such diverse chemical and physical properties, it is no surprise that it also has a wide range of applications. Since the 1960’s, aerogel has been used as the insulating material in spacesuits of NASA astronauts as, despite its wispy appearance, it is extremely strong and can survive take-off conditions easily.
In the early 21st century, aerogel was employed in a very special role by NASA- to capture space dust. Aerogel is being used in conjunction with the ‘Stardust’ mission, which aims to bring back particles from space from beyond the Moon for the first time. This dust is being primarily collected from the comet ‘Wild 2’. Aerogel is being used to capture this comet dust, as it will be able to trap the small particles without physically altering them. When the particle hits the aerogel, it will be traveling at speeds of up to 6 times that of a rifle bullet, which means most substances would not be able to slow the dust down without heating and thus alteration taking place. With aerogel, however, the dust buries itself into the porous material and is gradually brought to a stop as it loses momentum.
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