The purpose of this standard is to define: •The selection of critical items, the definition of cleanliness requirements to satisfy the mission performance requirements and control the levels to be met by personnel, items, facilities and operations of space projects.•The management, including organization, reviews and audits, acceptance status and documentation control.It covers design, development, production, testing, operation of space products, launch and mission.In this standard are also guidelines given for identification of possible failures and malfunctions due to contamination and guidelines for achieving and maintaining the required cleanliness levels during ground activities, launch and mission.This Standard applies to all types and combinations of projects, organizations and products, and during all the project phases, exceptmanned missions.It also applies to those ground systems that have a hardware interface to space systems, such as MGSE integration stands.This Standard does not address magnetic, electrical or electrostatic cleanliness.This Standard does not address completely biocontamination aspects. However, references to relevant ECSS standards are provided.This standard may be tailored for the specific characteristic and constrains of a space project in conformance with ECSS-S-ST-00.