Weight is a crucial factor in the cost of launching a spacecraft.
This has led to the creation of redundant systems. Thermal stability . A satellite moving in and out of the sun's rays is subjected to large cyclic temperature extremes over short periods of time. Spacecraft features which regulate temperatures, such as protective thermal blankets which reflect heat from spacecraft components facing the sun while simultaneously storing heat near components pointed away from the sun, are also necessary. Polymers can contain molecules which evaporate as time passes.