Effects of Water Vapor on Thermal Shield Materials

Three of the materials commonly used to insulate spacecraft from solar radiation are aluminized mylar, aluminized kapton, and silvered teflon. Damage to or deterioration of these materials would lead to large scale temperature excursions of the spacecraft. One possible mechanism for such deterioration would be the occurrence of high humidity prior to launch. A study was conducted to determine the vulnerability of these materials to humidity. It was found that aluminized mylar and aluminized kapton remain unaffected, but that silvered teflon is seriously damaged in a period of hours.