A Study of the Chemistry Between Fast Atomic Oxygen and Silver-Coated QCM Crystals

Atomic Oxygen (AO) is the main constituent of Low Earth Orbit (LEO), and it is responsible for chemical reactions on spacecraft materials that may degrade the performance or terminate the usefulness of them, and eventually accelerate the end of the life of the vehicle. This situation has make it clear the need to simulate the AO flux of LEO in a ground laboratory, to better understand the mentioned interactions.

MSRI and a UTSI team lead by Dr. Frank Collins have heavily modified an atomic oxygen generator originally fabricated by Dr. Gar Hoflund that promises to at least duplicate the AO flux of LEO. UTSI received the challenge to evaluate the performance of this generator. A Quartz Crystal Microbalance (QCM) with silver-coated crystals was used for this purpose, since it is the most mature and reliable technology available for the task.

The ultimate goal of this research is to assist the Arnold Engineering Development Center in its efforts to accurately simulate the LEO environment.

An extensive literature search proved that despite silver-coated QCMs are widely used both in the ground and in space, the chemistry between fast atomic oxygen and polycrystalline silver films in poorly understood. This thesis is an attempt to provide some light into this unknown chemistry. The implicated reactions are critical to properly calibrate the QCM instrument and to understand some reactions that take place in outer space.