Superlight
Aerospace engineers and architects, respectively, benefit enormously from the efficiency and versatility of porous gels and flexible films. In the realm of the superlights, less is always more. A material’s lightness is important to consider when designing such things as mobile structures, portable appliances, and fuel-efficient vehicles. With handheld electronic devices and electric cars, superlight lithium batteries are used in place of heavy lead-acid batteries; lightweight materials are especially critical for electric vehicles, since the point with these is to conserve energy. Carbon-fiber materials such as nylon and Kevlar, both light and strong, are commonly used for sporting equipment associated with speed, like car racing and cycling, and in the aerospace industry, where aerogel does most of its work today. Aerogel is as much as 99% air and is typically made out of silica, but it can be made out of a wide variety of materials, including carbon and polymers. According to The Guinness Book of World Records, the latest and lightest versions of aerogel weigh just 1.9 mg/cm3 and are produced by the Lawrence Livermore National Laboratory in California. Although it is the lightest solid on Earth, aerogel is primarily used aboard spacecraft as a collection device for interstellar and cometary dust. Its pores and particles are smaller than the wavelength of light and it has low thermal and sound conductivity. Aerogel is the thermal insulation material of choice for the Warm Electronics Boxes (WEBs) on the 2003 Mars Exploration Rovers.
SUPERLIGHT SOLID. Aerogels were developed in the 1930s, but have only recently found practical applications in space. Particles shot into aerogel at high velocities in an experiment leave carrot-shaped track marks (7.12). The insulating properties of aerogel protect the flower from the flame (7.13). A block of aerogel weighing only 2 g can support a brick weighing 2.5 kg (7.14).
