Cleanliness Plan - PA-3

To describe the approach for defining the measures ensuring compliance with performance requirements with regard to product contamination by particles and/or chemical species.

Two documents are required:

• Cleanliness Requirements Specification (CRS) setting out the specifications on surface molecular and/or particulate contamination,
• Cleanliness and Contamination Control Plan (C&CCP) in response to the CRS.

By definition, a contaminant is “any foreign matter that remains on a surface or in a functional environment long enough to degrade its performance or reduce its service life”. In the space industry, the three families of contaminants can be detrimental:

• particulate contamination (mainly on the ground): this corresponds to particles of visible inert matter (in the micrometre range) which are transported by fluids and build up on surfaces.
• molecular contamination (can be on the ground, but mainly in flight): this consists of deposits of droplets of varying homogeneity which form after the transportation of molecules in liquid or vapour form.
• biological contamination: this is caused by viable particles present on surfaces or in the ambient air.

Lessons learned from experience have led to increased awareness of the risks of damage and decreased performance in space systems due to chemical or particulate contamination. In this day in age, with instruments becoming more and more sophisticated, and quality and reliability constraints becoming more and more rigorous, contamination control is a necessity and must be applied throughout every stage in the development of a satellite – from the component level to the system level.

For this purpose, a regulatory framework has been instituted, and the risk minimisation rationale involves establishing a cleanliness plan for a given piece of equipment or for the fully integrated satellite, as set out in standard “RNC-ECSS-Q-70-01 Cleanliness and contamination control”. 

This standard defines the cleanliness rules and associated quality control to be implemented during operations within the project’s scope of responsibility, for components that are sensitive to contamination and components in close proximity to them.

In terms of the activities to be carried out, it complies with the cleanliness requirements that apply to the product in question.

The Cleanliness Plan is initialised by the project at the end of Phase A and its content is discussed with the Customer to ensure that it is in line with the cleanliness management processes between the project and its Customer. It is finalised at the end of Phase B.

The project's Cleanliness control approach is based on a process comprising the following steps:

• setting up the project’s Cleanliness organisation,
• identifying the components that are sensitive to contamination,
• identifying the sources of contamination,
• identifying the Cleanliness requirements that apply to the project,
• establishing an allocated contamination budget for each phase of the project,
• describing the measures taken to comply with this constraint.

Ultimately, the project needs to present an assessment of the contamination of sensitive components, to be compared with the contamination values deemed admissible in the contamination budget.

The aim is to cover the product’s entire life cycle, from the design phase to end of service life – including the procurement, manufacturing, integration, testing, storage and transportation phases.

In terms of the products in question, the Cleanliness scope covers:

• the design and development of all models (EM, QM, FM and the associated ground support equipment),
• the production of flight models and any non-flight component that may be in close proximity to flight models.

1. Purpose

This chapter introduces the general objectives and scope of the project Cleanliness Plan activities.

In particular, it clearly describes the product in question and the project to which it is related.

2. Scope

This chapter introduces the activities proposed to manage project requirements, in addition to the people involved throughout every phase of the project.

3. References

3.1 Reference documents

These constitute the bibliography required for the drafting of the Cleanliness Plan.

Note: RNC-ECSS-Q-ST-70-01 is the essential document.

3.2 Applicable documents

All documents applying to the drafting of the Cleanliness Plan.

3.3 Glossary

This paragraph provides the acronyms used in this document.

4. Organisation of Cleanliness activities

4.1 Inputs

This paragraph specifies the inputs for the Cleanliness Plan activities.

4.2 Outputs

This paragraph specifies the expected output of the Cleanliness Plan activities.

4.3 Organisation

This paragraph specifies the responsibilities of the persons responsible for the activities set out in the Cleanliness Plan.

4.4 Assumptions 

This paragraph sets out the assumptions on which the budget forecast is based.

5. Identification of sensitive components

All components requiring special precautions with regard to a risk of contamination are considered to be ‘sensitive' to contamination, even if the admissible contamination values are high.

Possible cases of sensitivity to moisture shall be taken into account.

The admissible contamination values indicated are those which are, at the end of the mission, compatible with the mission objectives.

5.1 Sensitive components

Components that are presumed to be sensitive are listed.

For each sensitive component, the allowable PC and MC values are provided, along with the references from which they were taken.

5.2 All other non-sensitive surfaces

For all surfaces that are not presumed to be sensitive, the admissible PC and MC values are also provided.

6. Identification of the sources of contamination

For general considerations on sources of contamination, refer to document RNC-ECSS-Q-ST-70-01 - Cleanliness and contamination control - Annex D, § D.2.1 Typical contaminants and their sources.

As this list is not exhaustive, other sources can be considered on a case by case basis, whether for the payload instruments or at the satellite level. Sources of cross contamination shall also be taken into account in the case of multiple stores.

7. Description of Cleanliness activities

This section lists all of the requirements to be taken into account with regard to cleanliness aspects and defines how the project complies with them in terms of setting up activities, persons responsible and ensuring traceability.

The requirements are derived from the Product Assurance specification that applies for the supply of equipment and their integration (identified in the example below in REQ-PA-xxx format) and specific additional Cleanliness requirements (identified in the example below in “REQ-PROP- xxxx” format).

8. Conclusion

Summary table of cleanliness requirements and allocations.