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Spie Press Book

Fundamentals of Contamination Control
Author(s): Alan C. Tribble
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Book Description

This Tutorial Text provides a comprehensive introduction to the subject of contamination control, with specific applications to the aerospace industry. The author draws upon his many years as a practicing contamination control engineer, researcher, and teacher. The book examines methods to quantify the cleanliness level required by various contamination-sensitive surfaces and to predict the end-of-life contamination level for those surfaces, and it identifies contamination control techniques required to ensure mission success.

Book Details

Date Published: 18 July 2000
Pages: 196
ISBN: 9780819438447
Volume: TT44

Table of Contents
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Preface
Acronyms
List of Terms
1 Introduction
2 Molecular Contamination
2.1 Effects of Molecular Films
2.1.1 Effects on Reflecting or Radiating Surfaces
2.1.1.1 Thermal Control Surfaces
2.1.1.1.1 Effects on Solar Absorptance
2.1.1.1.2 Effects on Emittance
2.1.1.2 Optical Elements-Mirrors
2.1.2 Effects on Transmitting Surfaces
2.1.2.1 Solar Array Coverslides
2.1.2.2 Optical Elements-Lenses, Focal Plane Arrays
2.1.3 Additional Concerns
2.1.3.1 Cryogenic Surfaces
2.1.3.2 Thin Molecular Films-Interference and Scattering
2.2 Quantifying Molecular Contamination
2.2.1 MIL STD 1246C
2.3 Generation, Transportation and Deposition of Molecular Contaminants
2.3.1 Contamination due to Materials Outgassing
2.3.1.1 Contamination Generation-Diffusion
2.3.1.1.1 ASTM E 595-Materials Outgassing Test
2.3.1.1.2 ASTM E 1559- Contamination Generation Characteristics of Spacecraft Materials
2.3.1.2 Contamination Transport
2.3.1.2.1 Line of Sight
2.3.1.2.2 Non-Line of Sight
2.3.1.2.2.1 Desorptive Transfer and Scattering
2.3.1.2.2.2 Electrostatic Re-attraction During Spacecraft Charging
2.3.1.3 Contamination Deposition-Surface Residence Time/Accumulation Rate
2.3.2 Contamination due to Thruster Plumes
2.4 Synergistic Effects
2.4.1 Photochemically Enhanced Deposition
2.5 Estimating End of Life Molecular Cleanliness Requirements
2.5.1 Example: Solar Arrays
2.5.2 Example: Thermal Control Surfaces
2.5.3 Example: Optical Sensors
2.6 Predicting End of Life Molecular Cleanliness Levels
2.6.1 Mass Loss
2.6.2 Mass Exitance
2.6.3 View Factors
2.6.4 Deposition
2.6.5 Comparison to Requirements
2.7 Design Guidelines for Controlling Molecular Contamination
3 Particulate Contamination
3.1 Effects of Particles
3.1.1 Surface Obscuration-Effects on Reflecting Surfaces
3.1.1.1 Optical Elements-Mirrors
3.1.1.2 Thermal Control Surfaces
3.1.2 Surface Obscuration-Effects on Transmitting Surfaces
3.1.2.1 Solar Arrays
3.1.2.2 Optical Elements-Lenses, Focal Plane Arrays, and Concentrated Optics
3.1.2.2.1 Additional Concerns for Focal Planes
3.1.3 Scattering
3.1.3.1 MIE Scattering
3.1.3.2 Effect of Particulates on Mie Theory Results
3.1.3.3 Bidirectional Reflectance Distribution Function (BRDF)
3.1.3.3.1 Point Source Transmittance (PST)
3.2 Quantifying Particulate Contamination
3.2.1 MIL STD 1246C
3.2.2 Percent Area Coverage
3.2.2.1 Additional Concerns
3.2.2.1.1 Directional Effects
3.2.2.2 Wavelength Effects
3.2.3 Bidirectional Reflectance Distribution Function (BRDF)
3.2.3.1 The Effects of Particulate Contamination on BRDF
3.2.3.2 The Effects of Molecular Contamination on BRDF
3.3 Generation, Transportation, and Deposition
3.3.1 Air Quality: FED STD 209E
3.4 Particle Redistribution During Launch and On Orbit
Operations
3.4.1 On Orbit Observations
3.4.2 Micrometeoroid & Orbital Debris Impact
3.5 Estimating End of Life Particle Cleanliness Requirements
3.5.1 Example: Solar Arrays
3.5.2 Example: Thermal Control Surfaces
3.5.3 Example: Optical Surfaces
3.6 Predicting End of Life Particulate Cleanliness Levels
3.6.1 Exposed Surfaces: Solar Arrays and Thermal Control Surfaces
3.6.2 Unexposed Surfaces: Optical Sensors
3.7 Design Guidelines for Controlling Particulate Contamination
4 Contamination Control
4.1 Preventing Contamination
4.1.1 Spacecraft Design
4.1.1.1 Configuration
4.1.1.1.1 Honeycomb Panels
4.1.1.2 Materials and Processes
4.1.1.2.1 Metals
4.1.1.2.2 Non-Metals
4.1.1.2.3 Processes
4.1.1.3 The Vehicle Interior-Electronic Boxes, Cable Harnesses,...
4.1.1.4 Electrical Power System-Solar Arrays
4.1.1.5 Thermal Control Surfaces
4.1.1.6 Attitude Determination & Control-Attitude Sensors
4.1.1.7 Propulsion-Thrusters
4.1.18 Other Exterior Surfaces
4.1.2 Optical Payload Accommodation
4.1.3 Ground Equipment
4.1.4 Manufacturing, Assembly, and Test
4.1.4.1 Parts Fabrication
4.1.4.2 Subassembly, Assembly, and Test
4.1.4.2.1 Test Chambers
4.1.4.3 Controlled Work Areas
4.1.4.3.1 Access
4.1.4.3.2 Cleanroom Training
4.1.4.3.3 Before Entering the Controlled Work Area
4.1.4.3.4 Entering the Garment Room and Controlled Work Areas
4.1.4.4 General Area Regulations
4.1.4.4.1 Receiving Area Entry
4.1.4.4.2 Movement Between Areas
4.1.4.4.3 Area Monitoring
4.1.4.4.4 Janitorial Service
4.1.4.5 Laminar Flow Area Regulations
4.2 Monitoring Contamination
4.2.1 Molecular Contamination
4.2.1.1 Gravimetric
4.2.1.2 Optical Stimulated Electron Emission (OSEE)
4.2.1.3 Quartz Crystal Microbalances (QCMs)
4.2.1.4 Calorimetry
4.2.2 Air Quality
4.2.2.1 Membrane Filter Sampling: ASTM F 25
4.2.2.2 Light Scattering: ASTM F 50
4.2.2.3 Dark Field Photography
4.2.3 Particulate Contamination
4.2.3.1 Visual Inspection
4.2.3.1.1 ASTM "Statistical" Procedures
4.2.3.1.2 NASA "Appearance" Procedures
4.2.3.1.3 Solar Arrays
4.2.3.1.4 Thermal Control Surfaces
4.2.3.1.5 Optical Surfaces
4.2.3.2 Scattering: ASTM E 1392
4.3 Cleaning Contaminated Surfaces
4.3.1 Removing Molecular Films
4.3.1.1 Solvent Wiping
4.3.1.2 Non-Contact Techniques
4.3.1.2.1 Thermal Heating
4.3.1.2.2 Charged Particle Beams
4.3.1.2.3 Plasma Sputtering
4.3.1.2.4 Laser Beams
4.3.2 Removing Particulates
4.4 Maintaining Surface Cleanliness
4.4.1 Storage
4.4.2 Transportation
4.4.3 Accident Recovery
4.5 Launch and Orbital Operations
4.5.1 Shuttle Processing Facilities
4.5.2 Early on Orbit Shuttle Contamination Environment
4.5.3 Lessons Learned: The Midcourse Space Experiment (MSX)
5 Bibliography
5.1 Government Documents
5.2 Industrial Standards
5.2.1 American Society for Testing and Materials (ASTM)
5.2.2 Institute of Environmental Sciences (IES)
5.3 Selected Public Domain References
5.3.1 Molecular Contamination
5.3.1.1 Effects of Molecular Films
5.3.1.1.1 Cryogenic Surfaces
5.3.1.2 Generation, Transport and Deposition
5.3.1.2.1 General
5.3.1.2.2 Thrusters
5.3.1.2.3 Spacecraft Charging Enhancement
5.3.1.2.4 Photochemical Deposition
5.3.1.3 Program Specific Documents
5.3.1.3.1 Shuttle
5.3.1.3.2 Long Duration Exposure Facility
5.3.1.3.3 Other Programs
5.3.1.4 Other Molecular
5.3.2 Particulate Contamination
5.3.2.1 Effects of Particulates
5.3.2.1.1 General
5.3.2.1.2 Scattering
5.3.2.1.3 BRDF
5.3.2.2 Optical Baffle Materials
5.3.2.3 Program Specific Documents
5.3.2.3.1 Shuttle
5.3.2.3.2 Other Programs
5.3.2.4 Other Particulates
5.3.3 Contamination Control
5.3.3.1 Cleanrooms
5.3.3.2 Controlling Particulates
5.3.3.3 Cleaning Techniques
5.3.3.4 Monitoring Techniques
5.3.3.5 Program Specific Documents
5.3.3.5.1 Shuttle
5.3.3.5.2 Hubble Space Telescope
5.3.3.5.3 Other
5.3.3.6 Other Contamination Control
5.3.4 General

Preface and Acknowledgements

This text provides a comprehensive introduction to the subject of contamination control, with specific applications to the aerospace industry. It is intended to provide insight on methods to: a) quantify the cleanliness level required by various contamination sensitive surfaces; b) predict the end of life contamination level seen by those surfaces; and c) identify the contamination control techniques required to ensure mission success. This document has evolved from NASA-CR-4740, Contamination Control Engineering Design Guidelines for the Aerospace Community, which was developed under contract to the NASA Space Environments & Effects (SEE) Program. The NASA SEE Program Office has graciously approved the republication of NASA-CR-4740 by the Society for Photo-Optical Instrumentation Engineers (SPIE). The material presented here has been updated to reflect the latest developments and also includes explicit examples of how the various concepts are applied.

The lessons learned here are based on many years experience as a practicing contamination control engineer and teacher. They are intended to provide practical solutions that will lead to a viable design, while minimizing cost and schedule impacts. As with any undertaking of this nature, the final product reflects the contributions of many individuals. Deserving special mention are: Dr. James Haffner, my mentor during the early days at Rockwell International's Satellite and Space Electronics Division; Mr. John Davis, my tutor on the finer points of sensor design; and Dr. Philip Chen of the NASA Goddard Space Flight Center, who helped guide the original NASA report to a successful conclusion. Last but not least, is the SPIE itself, for recognizing the importance of this topic and wishing to see it made available to a broader audience.

Alan C. Tribble, Ph.D. Intellectual Insights www.alantribble.com


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