Spacecraft charging effects on anodized aluminum surfaces

Because of a number of key properties, there is increased interest in using anodized aluminum on external spacecraft surfaces. Originally used by the space station program because aluminum is cheap and easy to anodize, it attracted attention because its optical properties, especially absorptivity and emissivity, can be tailored to produce a surface having excellent thermal control properties. Furthermore, since it is an oxide and is almost impervious to atomic oxygen (AO) it is ideal for use in low Earth orbit (LEO) where AO attack is a major design issue. In addition to these traditional uses of the material, the recent introduction of high-voltage space power systems has caused designers to take note of the excellent insulating properties of this material. As a result, both laboratory work as well as limited space testing has been performed. The authors show a typical sample from high voltage arc testing as well as a flight sample from the Solar Array module Plasma Interactions Experiment (SAMPIE). They believe their findings to apply generally to this material as they assess its value as a high voltage insulator in space