NOTE Before PDR an accurate geometrical model of a satellite is not generally available. As a consequence it is not possible to estimate the dose level expected at a part and so the final achieved RDM cannot be accurately assessed.
c. For parts whose achieved RDM determined from the worst-case assessment specified in requirement 5.6.2a and b falls below the MRDM specified in requirement 5.2a and where information is available, the worst case assessment shall be augmented by geometrical (sector-shielding) analysis.
d. The shielding analysis specified in requirement 5.6.2c may be iterated, improving the geometrical fidelity at each stage so as to converge on an RDM that meets or exceeds the MRDM.
NOTE The shielding analysis is based on evaluation of the basic spacecraft and unit geometries, with sufficient detail of major local spacecraft elements which can improve shielding. Monte-Carlo techniques can also be attempted at this stage. The achieved RDM is evaluated considering the environmental and shielding uncertainties and possible systematic conservatism.
e. For parts whose achieved RDM, as determined from the assessment in requirements 5.6.2a, b and c, falls below the MRDM specified in requirement 5.2a shall be:
1. declared by the supplier to have failed to meet the specification,
2. reported to the customer, and
3. either replaced with a part that meets the MRDM or subjected to detailed testing and analysis procedures.
NOTE 1 The tests and analysis procedures are specified in the clauses of ECSS-Q-ST-60 relevant to “Radiation Hardness”.
NOTE 2 This analysis can be performed after PDR when more detail of the system geometry is available for more accurate shielding analyses.