scope:

Purpose.

The purpose of this handbook is to present a methodology for the systematic screening of nonmetallic materials with a line of sight to an optical surface, thermal control surface, or other contamination sensitive surfaces in a vacuum environment. The outgassing measurements made using the methods described here will support configurational analysis of the release of molecular contamination from the surface of a material and facilitate the prediction of the deposition of condensable materials on one or more adjacent surfaces.

Applicability. This handbook is applicable to the test methodology used to evaluate the outgassing of nonmetallic materials used adjacent to contamination sensitive surfaces. This methodology is based on the American Society for Testing and Materials (ASTM), Standard Test Method for Contamination Outgassing Characteristics of Spacecraft Materials, Method E-1559, and describes methodology by which the outgassing source terms (rates) for nonmetallic materials should be measured. This measurement differs from the measurement described in the ASTM Standard Test Method for Total Mass Loss and Collected Volatile Condensable Materials from Outgassing in a Vacuum Environment (Method E-595) which is a less complex outgassing measurement; possibly an alternative to the E-1559 measurement. The outgassing rate data obtained from the E-1559 measurement will support configurational analysis of the emittance and deposition of contaminants while the data obtained from the E-595 measurement will not. (See Figure 1.)

The selection of either measurement is a Program/Project decision and should take into account both the duration that a contamination-sensitive surface will be exposed to the outgassing material and the amount of volatile condensable materials (Vim's) that can be deposited on a contamination-sensitive surface before the performance of the surface is degraded and/or no longer functional. In addition to deciding which measurement is the correct measurement to meet Program/Project needs, the Program/Project should identify a person or office to act as the Technical Authority. The Technical Authority will be charged with defining the criteria for the outgassing rate measurement as guidance to the technical community supporting the Program/Project.

This handbook may be cited in contract, Program/Project, and other Agency documents as a technical reference for guidance. Except where noted as mandatory, individual provisions of this reference may be tailored (i.e., modified or deleted) by contract or Program/Project direction to meet specific Program/Project needs and constraints. Tailoring shall be formally documented and approved as part of Program/Project Materials and Processes oversight.