Aerogels are the lightest solid material in the world, with up to 99.98% air by volume. They are nicknamed ‘frozen smoke’. They currently have 15 Guinness World Records.

The term ‘aerogel’ was first introduced in 1932 by Samuel Kistler, an American scientist and chemical engineer, to describe gels in which the liquid had been replaced by a gas. Gels had been previously been dried by evaporation but Kistler used the ‘supercritical drying’ technique, which is still used to produce aerogels today.

Removing all the liquid in a gel without changing the structure of it. This is done as follows: Alcogels are pressurized and cooled Liquid CO 2 Heated and pressurized Slow release of CO 2

Density 1.9 mg/cm 3 Tensile Strength 16 kPa

Aerogels have a complicated, cross-linked internal structure. Micropores = < 2 nm diameter Mesopores = 2-50 nm diameter Macropores = > 50 nm diameter

Young’s Modulus – 10 6 Pa

"You could take a two or three-bedroom house, insulate it with aerogel, and you could heat the house with a candle. But eventually the house would become too hot." - Dr. Peter Tsou of NASA's Jet Propulsion Laboratory

The main aim is to discover more about the origins of the solar system with cometary particles & interstellar dust. Relatively pure cometary samples can be obtained. These are useful because they are less likely to have cross-contaminated by neighboring bodies.

Collection Problems: Very high velocities leading to damaged samples Tiny particles impossible to find on collection Aerogel’s Solutions: Sponge-like structure provides safe, gradual stop for particles Transparency for ease of particle tracking

X-aerogels Insulating skylights Armor Non-deflatable tires Aircraft structural components Heat shields for spacecraft re- entry

temperature_phase_diagram.svg/220px-Carbon_dioxide_pressure-temperature_phase_diagram.svg.png Aerogels Handbook – Michel A. Aegerter The unbeatable lightness of aerogels: Take 10 parts of metal oxide, 90 parts of air, mix well - and watch industry fall upon the product with glee – New Scientist