A cleanroom is a secured environment where the level of particulate matter in the atmosphere is strictly controlled. All pollutants such as dust, chemical vapours, airborne microbes and aerosols are permanently monitored and eradicated by an internal conditioning system, which includes a combination of filters (HEPA and ULPA), extraction fans, airlocks, air showers and protective clothing for its workers.
Via this system, a controlled number of particles per cubic metre (and of a specific size) can be ensured, with higher-class facilities capable of delivering smaller and fewer particles. For instance, an ISO 1 cleanroom – the highest grade; there are nine in total – allows no more than two two- micrometre particles per cubic metre. For perspective, a typical urban environment has 35 million particles of all sizes per cubic metre. Cleanrooms are used by NASA when building, testing and integrating spacecraft components to ensure no contamination or damage is inadvertently done to the sensitive and expensive equipment – technology that once launched into space cannot be decontaminated.
Indeed, while tiny specks of dirt may seem insignificant, past experiences and studies have shown that even the tiniest piece of pollen, sand, hair or flake of skin can imbalance a star-tracking unit, damage an exhaust port or even lead to a spacecraft’s thruster becoming blocked.
As such, whenever a NASA engineer comes into work on the latest space technology, far from simply hanging up their coat and getting down to business they must first change into their protective clothing, pass through an air shower – essentially a human-sized hand- dryer that removes any particles stuck to the suit, proceed through a secure airlock equipped with extraction fans, and then finally pass through a temperature and humidity-controlled room to the assembly area. Only then, and under the constant filtering process of a laminar flow filtration system, can they begin work.