The International Space Stations solar array wingspan (240 feet) is about the same length as the world’s largest passenger aircraft, the Airbus A380.

One of the critical aspects of the International Space Station (ISS) is the mitigation of contamination.  In this case, we are talking about contamination via outgassing.  Outgassing is the release of molecules from a material.  A good example of outgassing is the new car smell we experience.  This smell comes from the materials used to manufacture the vehicle outgassing. 

While outgassing may not seem like an issue when discussing the new car smell, it is an issue in enclosed spaces like spacecraft or submarines.  Once this outgassing occurs, the molecules can then deposit on surfaces and contaminate the environment, affecting performance, especially for sensitive optics.   

In order to mitigate this risk, the ISS has external contamination control requirements.  These include placing limits on acceptable outgassing, submitting lists of material being used for review, maintaining test results, and requiring thermal vacuum baking for a material known to outgas.

It is extremely important to maintain a level of contamination control in the ISS, and even with these requirements outgassing does occur.  The goal now is to minimize the exposure of the ISS to this outgassing and maintain a clean high-vacuum environment.