All space systems and associated equipment procured by the European Space Agency are required to conform to the Agency's Product Assurance (PA) requirements as set out in the ECSS and ESAPSS series of documents. In addition, safety requirements imposed on ESA by the respective Launcher Authorities are mandatory on all flight hardware and software and hence the relevant requirements are applicable for all items. It is stressed that, the safety regulations of the relevant Ariane launcher need to be complied with. The PA requirements and guidelines defined herein are derived from the entire set of applicable documentation, and have been tailored to the scientific instruments.