• Version
• 192 Downloads
• 913.73 KB File Size
• 1 File Count
• April 6, 2016 Create Date
• April 6, 2016 Last Updated

Contamination Control Engineering Design Guidelines for the Aerospace Community

1. Introduction

1.1 Objective

Contamination may be simply defined as any foreign matter. In general, contamination is
grouped into two broad categories labeled molecular and particulate. Molecular contamination refers
to the cumulative buildup of individual molecules of foreign matter. An example of molecular
contamination is the familiar odor of plastics or the “new car smell”. These are indications of volatile
molecules being generated by organic materials. Molecular contamination may occur during ground
processing, but is usually of more concern on orbit, (H20 especially). Particulate contamination refers
to the deposition of visible, (um sized), conglomerations of matter. Surfaces that become dusty and
eyeglasses that require periodic wiping are an indication of the presence of particles in the
atmosphere. These particles, which are deposited mainly during ground operations, will fall from the
air onto exposed surfaces.

Effective contamination control is essential for the success of most aerospace programs because
the presence of contamination, even in miniscule quantities, can degrade the performance of
spacecraft hardware. The presence of contamination on thermal control surfaces will alter
absorptance/emittance ratios and change thermal balance, while contamination on solar arrays will
decrease power output. Contamination in optical instruments will decrease signal throughput and can
scatter the signal beyond the diffraction design, thus further decreasing performance. The end result
of contamination may be intuitively obvious. What is not obvious, however, is how one: a) quantifies
the critical level of contamination, and b) enforces contamination control to ensure compliance with
requirements. Consequently, the objective of this document is two-fold. First, to furnish spacecraft
system engineers and payload providers with a means of quantifying the contamination cleanliness
levels required for proper performance of their equipment, and second, to provide insight into what
procedures and processes will have to be maintained during fabrication, assembly, integration, test,
launch and operation in order to maintain those levels on orbit.

As illustrated in Figure 1-1, contamination control for a space program is an iterative process
that flows from the mission objective directly into design and operations.