ISO 15388:2022

Space systems - Contamination and cleanliness control

This document establishes general requirements for contamination and cleanliness control that are applicable, at all tiers of supply, to the development of space systems, including ground processing facilities, ground support equipment, launch vehicles, spacecraft, payloads, and ground processing and on-orbit operations. It also provides guidelines for the establishment of a contamination and cleanliness control programme.

Systèmes spatiaux — Contrôle de la contamination et de la propreté

General Information

• Status: Published
• Publication Date: 24-Oct-2022
• ICS: 49.140 - Space systems and operations
• Technical Committee: ISO/TC 20/SC 14 - Space systems and operations
• Drafting Committee: ISO/TC 20/SC 14/WG 6 - Materials and processes
• Current Stage: 6060 - International Standard published
• Start Date: 25-Oct-2022
• Due Date: 24-Apr-2022
• Completion Date: 25-Oct-2022

Relations

• Revises: ISO 15388:2012 - Space systems - Contamination and cleanliness control
• Effective Date: 23-Apr-2020

Overview

ISO 15388:2022 - "Space systems - Contamination and cleanliness control" defines general requirements and guidance for preventing particulate, molecular and biological contamination across the full lifecycle of space systems. Applicable at all tiers of supply, it covers ground processing facilities, ground support equipment (GSE), launch vehicles, spacecraft, payloads, and both ground and on‑orbit operations. The standard also guides development of a contamination and cleanliness control programme to protect mission performance and ensure objectives are met.

Key topics and technical requirements

ISO 15388:2022 organizes contamination control into management, design, biological control and operational activities. Important topics include:

• Management and planning
  • Cleanliness Requirement Specification (CRS) and Contamination and Cleanliness Control Plan (CCCP)
  • Interface Control Documents (ICD) and project reviews to coordinate supplier responsibilities
• Design activities
  • Identification of contamination‑sensitive hardware and cleanliness‑oriented design
  • Contamination prediction and establishment of a contamination budget
  • Material selection with attention to outgassing, offgassing and absorbed water vapor
• Biocontamination
  • Controls for microbial contamination, sterile hardware, habitable systems, planetary protection and sample protection
• Ground operations and facilities
  • Cleanroom selection and operating procedures, garment selection, facility failure planning
  • Training, GSE cleanliness, monitoring of hardware and nearby environments
• Cleaning, packaging and transport
  • Cleaning procedures, bakeout (temperature‑driven outgassing reduction), purging, containment, storage and transport practices
• Analysis and uncertainty
  • Annex B: guidelines for contamination analysis procedures
  • Annex C: factors for combined uncertainty in measurements

Practical applications and users

ISO 15388:2022 is used to define baseline cleanliness requirements and to harmonize practices across suppliers and contractors. Typical users include:

• Spacecraft and payload system engineers and program managers
• Contamination control engineers and cleanliness assurance teams
• Cleanroom and facility managers, test and integration personnel
• Procurement and quality assurance professionals specifying CRS/CCCP
• Planetary protection officers and astromaterials custodians
• Laboratories performing contamination analyses and outgassing tests

Applying this standard helps reduce performance degradation (optical, thermal, mechanical, fluid systems), protects sensitive instrumentation, improves repeatability of test campaigns, and supports compliance with planetary protection and sample‑return requirements.

Related standards (normative references)

ISO 15388:2022 references several complementary standards often used together:

• ISO 14624‑3 (offgassed products)
• ISO 14644‑1 (cleanroom classification)
• ISO 14698‑1 / 14698‑2 (biocontamination control)
• ISO 14952‑2 / 14952‑3 (fluid system surface cleanliness and analysis)
• ASTM E595 (outgassing test method)
• ECSS‑Q‑ST‑70‑02C (thermal vacuum outgassing screening)

Keywords: ISO 15388:2022, contamination control, cleanliness control, space systems, cleanroom, outgassing, bakeout, biocontamination, contamination budget, CRS, CCCP, GSE, planetary protection.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15388
Third edition
2022-10
Space systems — Contamination and
cleanliness control
Systèmes spatiaux — Contrôle de la contamination et de la propreté
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 7
4 Management . 8
4.1 Organization . 8
4.2 Cleanliness requirement specification (CRS) . 8
4.3 Contamination and cleanliness control plan (CCCP) . 8
4.4 Interface control document (ICD) . 9
4.5 Project reviews . 9
5 Design activities . 9
5.1 Identification of sensitive hardware . 9
5.2 Nature of contaminants, their profile and their effects . 9
5.2.1 General . 9
5.2.2 Typical contaminants . 9
5.2.3 Contamination profile . 10
5.2.4 Effects of contamination on performance . 10
5.3 Contamination prediction . 10
5.4 Contamination budget . 10
5.5 Cleanliness-oriented design . 10
5.6 Selection of materials and processes . 11
5.6.1 General . 11
5.6.2 Outgassing. 11
5.6.3 Absorbed water vapour. 11
5.6.4 Offgassing .12
5.6.5 Quality control .12
6 Biocontamination .12
6.1 General .12
6.2 Contamination of hardware by microorganisms .12
6.3 Sterile hardware .12
6.4 Habitable space systems . 13
6.4.1 Habitable spacecraft . 13
6.4.2 Offgassing .13
6.5 Planetary protection .13
6.6 Sample protection.13
7 Contamination and cleanliness control for ground operations .13
7.1 Training of personnel.13
7.2 Cleanroom selection and cleanliness control. 14
7.2.1 General . 14
7.2.2 Failure of facilities. 14
7.2.3 Facility operating procedures . 14
7.2.4 Additional information . 14
7.3 Cleanroom garments . 15
7.3.1 General .15
7.3.2 Considerations for garment selection . 15
7.3.3 Additional information .15
7.4 Ground support equipment (GSE) . 15
7.5 Monitoring cleanliness of flight hardware and its near surroundings .15
7.6 Packaging, storage and transport . 16
iii
7.6.1 Packaging . 16
7.6.2 Storage . 16
7.6.3 Transport . 16
7.7 Cleaning of flight hardware . 16
7.7.1 General . 16
7.7.2 Cleaning procedures . 16
7.7.3 Bakeout . 16
7.7.4 Contaminant source containment . 17
7.7.5 Purging . 17
Annex A (informative) Material properties — Electronic databases .18
Annex B (informative) Contamination analysis .19
Annex C (informative) Factors of combined uncertainty .30
Bibliography .31
iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 14, Space systems and operations.
This third edition cancels and replaces the second edition (ISO 15388:2012), which has been technically
revised.
The main changes are as follows:
— Annex B, which details guidelines for contamination analysis procedures, is added;
— Annex C, which indicates factors of combined uncertainty, is added;
— the latest international and national documents for planetary protection are referenced in 6.5.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
This document addresses the preferred programme elements recommended for contamination and
cleanliness control of space systems. This document is written in general terms as a baseline for
developing and implementing the control programme. It can be cited as a baseline within a statement
of work and/or used for assuring proposal precision and contractor performance. The users are
responsible for integrating the elements of this document appropriately to their programme needs.
The purpose of contamination and cleanliness control is to prevent the degradation of the performance
of space systems due to particulate and molecular contamination (including biocontamination), and to
ensure that the mission objectives are achieved.
vi
INTERNATIONAL STANDARD ISO 15388:2022(E)
Space systems — Contamination and cleanliness control
1 Scope
This document establishes general requirements for contamination and cleanliness control that are
applicable, at all tiers of supply, to the development of space systems, including ground processing
facilities, ground support equipment, launch vehicles, spacecraft, payloads, and ground processing and
on-orbit operations. It also provides guidelines for the establishment of a contamination and cleanliness
control programme.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 14624-3, Space systems — Safety and compatibility of materials — Part 3: Determination of offgassed
products from materials and assembled articles
ISO 14644-1, Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness
by particle concentration
ISO 14698-1, Cleanrooms and associated controlled environments — Biocontamination control — Part 1:
General principles and methods
ISO 14698-2, Cleanrooms and associated controlled environments — Biocontamination control — Part 2:
Evaluation and interpretation of biocontamination data
ISO 14952-2, Space systems — Surface cleanliness of fluid systems — Part 2: Cleanliness levels
ISO 14952-3, Space systems — Surface cleanliness of fluid systems — Part 3: Analytical procedures for the
determination of nonvolatile residues and particulate contamination
ASTM E595, Standard Test Method for Total Mass Loss and Collected Volatile Condensable Materials from
Outgassing in a Vacuum Environment
ECSS-Q-ST-70-02C, Space product assurance — Thermal vacuum outgassing test for the screening of space
materials
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
bakeout
activity of increasing the temperature of hardware to accelerate its outgassing (3.1.28) rates with the
intent of reducing the content of molecular contaminants (3.1.11) within the hardware
Note 1 to entry: Bakeout is usually performed in a vacuum environment but may be done in a controlled
atmosphere.
3.1.2
bioaerosol
dispersed biological agents [e.g. viable particles (3.1.29), allergens, toxins or biologically active
compounds of microbial origin] in a gaseous environment
3.1.3
biocontamination
contamination of materials, devices, individuals, surfaces, liquids, gases or air with viable particles
(3.1.29)
3.1.4
clean bench
table or bench-top working surface where a filtered airflow is concentrated across the bench top
Note 1 to entry: These bench tops have an established classification of maximum allowable airborne contaminants
(3.1.11).
3.1.5
cleanliness level
established maximum allowable amount of contamination in a given area or volume, or on a component
Note 1 to entry: The term may also apply to the predicted or measured extent of contamination.
3.1.6
cleanliness requirement specification
CRS
document that defines and identifies the spacecraft items and the environmental areas which are
sensitive to contamination, the acceptable contamination levels at beginning and end of life and the
applicable contamination environment
3.1.7
cleanroom
room within which the number concentration of airborne particles (3.1.29) is controlled and classified,
and which is designed, constructed and operated in a manner to control the introduction, generation
and retention of particles inside the room
Note 1 to entry: The class of airborne particle concentration (3.1.30 and 3.1.31) is specified.
Note 2 to entry: Levels of other cleanliness attributes such as chemical, viable or nanoscale concentrations in the
air, and also surface cleanliness (3.1.39) in terms of particle, nanoscale, chemical and viable concentrations might
also be specified and controlled.
Note 3 to entry: Other relevant physical parameters might also be controlled as required, e.g. temperature,
humidity, pressure, vibration and electrostatic.
[SOURCE: ISO 14644-1:2015, 3.1.1]
3.1.8
cleanroom garment
clothing designed, manufactured and worn specifically to prevent contamination of hardware by
personnel working in the cleanroom (3.1.7)
Note 1 to entry: Cleanroom garments include all items worn by personnel, such as coveralls, frocks, gloves, boots,
finger cots and beard covers.
3.1.9
clean zone
defined space within which the number concentration of airborne particles (3.1.29) is controlled and
classified, and which is constructed and operated in a manner to control the introduction, generation
and retention of contaminants (3.1.11) inside the space
Note 1 to entry: The class of airborne particle concentration (3.1.30 and 3.1.31) is specified.
Note 2 to entry: Levels of other cleanliness attributes such as chemical, viable or nanoscale concentrations in the
air, and also surface cleanliness (3.1.39) in terms of particle, nanoscale, chemical and viable concentrations might
also be specified and controlled.
Note 3 to entry: A clean zone(s) can be a defined space within a cleanroom (3.1.7) or might be achieved by a
separative device. Such a device can be located inside or outside a cleanroom.
Note 4 to entry: Other relevant physical parameters might also be controlled as required, e.g. temperature,
humidity, pressure, vibration and electrostatic.
[SOURCE: ISO 14644-1:2015, 3.1.2]
3.1.10
collected volatile condensable material
CVCM
mass that outgasses from a material and subsequently condenses on a collector, expressed as a
percentage of the initial specimen mass
3.1.11
contaminant
unwanted molecular or particulate matter that can affect or degrade the relevant performance or
lifetime of the hardware to which it is attached
3.1.12
contamination
introduction of any undesirable molecular or particulate matter (including microbiological matter) into
an item or into the environment of interest
[SOURCE: ISO 10795:2019, 3.62]
3.1.13
contamination and cleanliness control programme
organized effort to establish and achieve acceptable cleanliness and contamination levels during all
phases of the space system project
3.1.14
contamination and cleanliness control plan
CCCP
document that describes how to implement a contamination and cleanliness control programme (3.1.13),
as either an independent document or a part of the consolidated project plan
3.1.15
contamination budget
allowable levels of contamination of hardware at each phase of ground and flight operations
3.1.16
contamination profile
contamination-related conditions in each phase of ground and flight operations
Note 1 to entry: Conditions include airborne particulate cleanliness classes, pressure, humidity, temperature,
number of personnel engaged in operations, cleaning activities, outlines of facilities and so on.
Note 2 to entry: The contamination profile is part of the contamination and cleanliness control plan (CCCP) (3.1.14).
3.1.17
cross-contamination
transfer of contaminants (3.1.11) from one surface or component to another
Note 1 to entry: Transfer can occur by migration along a surface, by physical contact, airborne as an aerosol, or as
a gas or molecular matter.
3.1.18
debris
solid objects with their largest dimension greater than approximately 1 mm (1 000 μm) in size
3.1.19
electrostatic discharge
ESD
electrical breakdown of dielectric or gas or vacuum gaps, and also of surface interface of dissimilar
materials, caused by differential charging of parts of dielectric materials and their interfaces
[SOURCE: ISO 11221:2011, 2.10, modified — The abbreviated term "ESD" has been added.]
3.1.20
generally clean
free from manufacturing residue, dirt, oil, grease, processing debris (3.1.18), or other extraneous
contamination based on visual examination
Note 1 to entry: This level does not apply to hardware that is sensitive to contamination.
[SOURCE: ISO 14952-1:2003, 2.12, modified — The abbreviated term "GC" has been removed.]
3.1.21
ground support equipment
GSE
non-flight systems, equipment or devices necessary to support the operations of transporting,
receiving, handling, assembly, inspection, test, checkout, servicing, launch and recovery of a space
system at launch, landing or retrieval sites
[SOURCE: ISO 14625:2007, 3.1.5]
3.1.22
interface control document
ICD
specification that describes the characteristics that must be controlled at the boundaries between
systems, subsystems and other elements
3.1.23
microorganism
microscopical individual constituted to carry out life functions
Note 1 to entry: Microorganisms include organisms such as bacteria, protozoa, yeasts, moulds, fungi, algae and
organisms that depend upon other life forms for reproduction such as viruses and parasites.
Note 2 to entry: Multicellular organisms and agglomerations of microorganisms may be visible to the unaided
eye.
3.1.24
molecular contamination
contamination due to deposition of molecules on surfaces or their presence in gases or liquids
3.1.25
at-rest
condition where the cleanroom (3.1.7) or clean zone (3.1.9) is complete with equipment installed and
operating in a manner agreed upon, but with no personnel present
[SOURCE: ISO 14644-1:2015, 3.3.2]
3.1.26
operational
agreed condition where the cleanroom (3.1.7) or clean zone (3.1.9) is functioning in the specified
manner, with equipment operating and with the specified number of personnel present
[SOURCE: ISO 14644-1:2015, 3.3.3]
3.1.27
offgassing
evolution of gaseous products from a liquid or solid material into an atmosphere
Note 1 to entry: This is for the application in habitable volume considering medical impact on human health.
3.1.28
outgassing
evolution of gaseous species from a material, usually in a vacuum
3.1.29
particle
unit of solid or liquid matter with observable size
[SOURCE: ISO 14952-1:2003, 2.20]
3.1.30
particle concentration
〈on surface〉 number of particles (3.1.29) per unit area
3.1.31
particle concentration
〈by volume〉 number of particles (3.1.29) per unit volume of fluid
3.1.32
responsible organization
organization that is responsible for the contamination and cleanliness control programme (3.1.13) and
which is provided with the authority and resources needed to carry out the programme
3.1.33
recovered mass loss
RML
ratio of the total mass loss (3.1.40) of the specimen without the sorbed water to the initial mass:
w = w − w
RML TML WVR
where
w is the recovered mass loss, in per cent;
RML
w is the ratio of the total mass loss to the initial mass, in per cent;
TML
w is the ratio of the water vapour regained (3.1.42) to the initial mass, in per cent.
WVR
Note 1 to entry: The quantity RML is introduced because water is not a critical contaminant (3.1.11) for some
space systems (see 5.6.3). In most cases, the value of WVR is similar to that of the mass of outgassed water.
However, WVR is not exactly the same as the water mass effused from the specimen. Therefore, RML is not equal
to the real value of the mass loss other than water.
3.1.34
sensitive hardware
hardware that can be degraded by contamination
3.1.35
significant surface
surface of an item or product that is required to meet established cleanliness level (3.1.5) requirements
3.1.36
spacecraft charging
increase in electrostatic potential on spacecraft surfaces resulting from low-energy electron flux
impinging on the surface
3.1.37
sterility
absence of viable microorganisms (3.1.23)
Note 1 to entry: Inactivated microbes can still represent an important form of biocontamination (3.1.3).
3.1.38
supplier
provider
organization that provides a product or a service
EXAMPLE Producer, distributor, retailer or vendor of a product or a service.
Note 1 to entry: A provider can be internal or external to the organization.
Note 2 to entry: In a contractual situation, a provider is sometimes called “contractor”.
[SOURCE: ISO 9000:2015, 3.2.5, modified —"provider" has been changed to an admitted term.]
3.1.39
surface cleanliness
level of contamination on a significant surface (3.1.35)
3.1.40
total mass loss
TML
total mass of material outgassed from a test specimen that is maintained at a specified constant
temperature and operating pressure for a specified time and measured within the test chamber
Note 1 to entry: TML is expressed as a percentage of the initial specimen mass.
3.1.41
visibly clean
absence of surface contamination when examined using a specified light source and angle of incidence,
viewing distance and angle, and normal or magnified vision
Note 1 to entry: This level requires precision-cleaning methods but a particle (3.1.30) count may be optional.
Note 2 to entry: Fluorescence indicates possible contamination by, for example, a hydrocarbon.
Note 3 to entry: If recleaning fails to remove fluorescent indications, an investigation should be made to
determine if the item material is naturally fluorescent or if the cleaning method is adequate.
[SOURCE: ISO 14952-1:2003, 2.35, modified — The abbreviated term "VC" has been removed.]
3.1.42
water vapour regained
WVR
mass of water vapour absorbed by a test specimen, after determination of total mass loss (TML) (3.1.40)
and collected volatile condensable material (CVCM) (3.1.10), on exposure to a specified relative humidity
atmosphere (usually 50 % at 23 °C or 65 % at 20 °C) for 24 h
Note 1 to entry: Some types of materials continue to absorb water for longer than 24 h. Repeated mass
measurements after various time periods (e.g. 24 h, 48 h and 72 h) give a better understanding of the material's
water absorbency.
3.2 Abbreviated terms
AIT assembly, integration and test
AO atomic oxygen
BOL beginning of (operational or mission) life
CCCP contamination and cleanliness control plan
CRS cleanliness requirement specification
CVCM collected volatile condensable material
ECSS European Cooperation for Space Standardization
EOL end of (operational or mission) life
ESA European Space Agency
ESA exposed surface area
ESD electrostatic discharge
GSE ground support equipment
GSFC Goddard Space Flight Center (NASA)
ICD interface control document
IEST Institute of Environmental Sciences and Technology (USA)
JAXA Japan Aerospace Exploration Agency
NASA National Aeronautics and Space Administration (USA)
NPD NASA policy directive
NPG NASA procedures and guidelines
RML recovered mass loss
TML total mass loss
UV ultra violet
WVR water vapour regained
4 Management
4.1 Organization
The supplier shall establish a contamination and cleanliness control programme at the beginning of
the project, for each level of configuration and item defined in the project. Performance requirements,
defined by customer-supplier agreements, form the basis for cleanliness requirements.
4.2 Cleanliness requirement specification (CRS)
The supplier shall identify the hardware to be controlled, and specify the permissible cleanliness level
in a quantitative manner. The hardware includes all items from component level to system level. The
acceptable cleanliness levels of the hardware shall be specified at BOL and EOL, based on performance
requirements and contamination analyses. The specification shall be established independently as a
CRS or included in an overall project design specification. The cleanliness of hardware to be controlled
at the boundary of systems, subsystems and other elements shall be stipulated in the ICD or its
equivalent.
Cleanliness requirements that are more stringent than necessary to meet manufacturing and system
performance requirements shall not be imposed at any level of assembly.
4.3 Contamination and cleanliness control plan (CCCP)
4.3.1 Specifying cleanliness necessitates the establishment of a budget for particulate and molecular
contamination for all phases of the project and a clear methodology of how the required cleanliness
levels can be achieved.
4.3.2 The supplier shall develop a contamination and cleanliness control plan that describes how to
achieve and maintain the specified cleanliness level of the hardware during all the phases of the ground
and flight operations. The plan may be an independent document or part of a consolidated project
control plan.
4.3.3 The range of the plan and the level of detail shall be determined by the responsible organization
with respect to the criticality of the hardware against contamination. This may require other tasks in
addition to those described in this document or may lead to a reduction in the applicable requirements.
4.3.4 The CCCP shall
a) contain a contamination budget for all phases of the ground and flight operations,
b) provide methodology for achieving and maintaining the required cleanliness levels,
c) define how to deal with situations that may result in cleanliness specifications not being achieved,
NOTE 1 Possible situations include failures of facilities and launch delays for a spacecraft.
NOTE 2 Corrective actions can include additional cleaning operations.
d) define single-point failure modes that can affect cleanliness, including equipment failures and
human errors,
e) define the risk of cross-contamination between hardware elements,
f) provide measurement and monitoring methods, procedures and requirements,
g) define the sequence of cleanliness activities,
h) define the roles and responsibilities of the organizations which will implement the requirements,
i) provide descriptions of when and how the cleanliness activities are to be reviewed,
j) provide information on how to implement design activities,
k) provide information on how to train personnel and assess them, and
l) provide references to procedures.
4.4 Interface control document (ICD)
4.4.1 The cleanliness of hardware to be controlled at the interfaces of different systems, subsystems
and other elements shall be stipulated in the ICD or its equivalent.
4.4.2 The ICD may include the following types of information:
a) limitations on particles, gases, vapours and debris crossing the interface;
b) limitations on particles, gases, vapours and debris in the field of view of instruments and sensors;
c) limitations on energy (ultraviolet and ionizing radiation, thermal radiation, radio frequency
radiation, etc.) that affect contaminant deposition and degrade performance.
4.5 Project reviews
The status of the contamination and cleanliness control programme shall be recorded and reported at
the milestone project reviews where it shall be demonstrated that suitable activities are planned, are
being implemented or have been successfully achieved.
5 Design activities
5.1 Identification of sensitive hardware
The supplier shall identify the sensitive hardware that may be degraded due to contamination during
ground processing or flight and that shall be suitably protected. This hardware becomes the subject of
detailed contamination and cleanliness control.
EXAMPLE Sensitive hardware includes optical detectors, optical assemblies and thermal control surfaces.
5.2 Nature of contaminants, their profile and their effects
5.2.1 General
The supplier shall identify:
a) the nature of the contaminants which may degrade the performance of sensitive hardware in any
way, such as particulate, molecular or biocontaminants, during all phases of ground and flight
operations;
b) the effects of contaminants on the sensitive hardware, using experience gained with similar
spacecraft or similar operations in early phases of the project and, later, using data gained in
realistic tests.
5.2.2 Typical contaminants
Typical contaminants are caused by factors such as outgassing (including re-emission of condensed
contaminants, and return flux from collisions with the ambient atmosphere and spacecraft charging at
high-Earth orbits); particles from materials, mechanisms or AIT facilities; grease from human handling,
operation and AIT facilities; launch contaminants; leakage from pressurized units; microorganisms;
ESD; arcing-induced contaminants on solar cell coverglasses; exhaust products from thrusters; natural
environments such as electron, proton and atomic oxygen fluxes; spacecraft charging; human waste
dumps; and contamination from life support hardware.
5.2.3 Contamination profile
The supplier shall initiate the contamination profile that shows contamination-related issues, such as
temperature, pressure, humidity and natural environments, in each phase of the life cycle and shall
maintain it throughout development.
5.2.4 Effects of contamination on performance
The supplier shall develop a correlation between contamination levels and degradation in performance,
and determine the allowable contamination limit for sensitive hardware. The cleanliness level
requirements shall be estimated in the early phases and become more detailed through performance
analysis.
5.3 Contamination prediction
The supplier shall perform an analysis of contaminant transport and deposition for all phases of
ground and flight operations. If the level of contamination exceeds the specifications, protective
measures shall be implemented. The parameters necessary to perform the analysis can include view
factors; the outgassing kinetics of relevant materials; the condensation kinetics and temperatures of
significant surfaces; temperatures of outgassing sources; the reflectance on the surfaces; the scattering
interactions with the neutral space environment; the electrodynamic interactions with ambient space
plasma; surface interactions with space radiation, particularly with the incident ultraviolet radiation;
etc.
Annex B details guidelines for contamination analysis procedure.
Annex C indicates factors and relations of combined uncertainty that is contained in contamination
analysis result.
5.4 Contamination budget
The supplier shall develop a contamination budget for both particulate and molecular species based
on the contamination profile and design specification of hardware cleanliness. The contamination
budget shall take into account the results of predictions, the probability of restoring cleanliness during
ground and flight operations, as well as exposure times and the use of protective covers. Methods to be
used for cleaning and maintaining cleanliness throughout all phases of the project shall be considered.
Contamination levels for BOL and EOL shall be included in the budget.
5.5 Cleanliness-oriented design
The supplier shall develop methods to maintain the cleanliness of sensitive hardware, to reduce its
sensitivity to contamination and to ease cleaning, and shall describe the outline of the cleanliness-
oriented design in the CCCP. Typical preventive measures include ensuring suitable location and
orientation of sensitive hardware; de-contamination heater on sensitive surfaces; minimizing the
usage of outgassing materials; using venting holes, baffles and shields; using protective covers on the
ground; controlling the temperature of outgassing hardware; designing cleaning processes; enclosing
contamination sources; baking; processing human wastes; using molecular adsorbers, etc. The
measures shall be chosen based on the cleanliness specification and the contamination budget.
The design of ground support equipment that is in the same room as, in close proximity to or in contact
with, flight hardware shall also be similarly considered.
5.6 Selection of materials and processes
5.6.1 General
Materials and processes shall be selected to minimize contamination as well as to meet other
functional requirements. The primary screening items for materials are outgassing, offgassing, particle
generation, fungus growth and fragility.
5.6.2 Outgassing
The initial screening of materials shall be in accordance with ASTM E595 or ECSS-Q-ST-70-02C.
Materials having TML of less than 1,0 %, RML of less than 1,0 % and CVCM of less than 0,1 % are
generally considered as low-outgassing materials. The figures do not represent the acceptance criteria.
Materials should be selected considering also temperature, mass and surface area in use.
A material is considered as a possible contamination source under the following conditions. In these
cases, even a low-outgassing material can cause contamination problems.
a) The material is used nearby, or in direct view of, the contamination-sensitive surfaces.
b) The material is used nearby, or in direct view of, the cryogenic surfaces.
c) The material is used in large amounts.
d) The material is expected to be at a higher temperature than other surfaces.
A material is considered to pose less of a risk of contaminating other surfaces under the following
conditions. In these cases, materials not considered as low-outgassing material can be applied with no
or small contamination impact.
— The material is used far from, or is not in direct view of, the contamination-sensitive surfaces.
— The material is used far from, or is not in direct view of, the cryogenic surfaces.
— The material is used in small amounts.
— The material is expected to be at a lower temperature than other surfaces.
The requirements for the use of TML and RML depend on the performance requirements for the space
system and specific uses of materials in the system (see 5.6.3).
Materials that pass the standard screening tests may nevertheless cause degradation of sensitive
hardware and may require further characterization. The customer and supplier shall establish
materials selection guidelines, with requirements that are more stringent, using other test methods, if
justified by mission and performance requirements.
Material selection adequacy is verified by contamination prediction (see 5.3). Even materials which do
not meet the materials selection guidelines may be used as long as the predicted level of contamination
meets the contamination budget (see 5.3 and 5.4).
NOTE 1 Properties such as TML, RML, CVCM and WVR of often used materials are publicly available on the
electronic databases listed in Annex A.
NOTE 2 Long-term outgassing estimation using ASTM E1559 (see Reference [34]) and other, similar test
methods are applicable for establishing guidelines for the selection of materials.
5.6.3 Absorbed water vapour
Some materials contain large quantities of absorbed water that contribute to the TML. If the outgassing
of water vapour is not critical to the application, the outgassed water may be subtracted from the TML
to provide an RML to meet the requirements. The adjusted mass loss value is given by the RML.
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