Application of GEVS to Risk Tolerant Missions

Environmental testing at NASA Goddard Space Flight Center has evolved since NASA began nearly 60 years ago, contributing to >99% mission success record over the past 30 years. Early thermal workmanship stress screening focused more on “time at temperature”, and results were mixed, perhaps due to the infancy of space exploration and the electronics packaging industry more than testing. Throughout most of the 1960’s, verification test programs were created for each launch vehicle, with specific tests and test levels for each. From the original General Environmental Test Specification for Spacecraft and Components (S-320-G-1) in 1969 to the latest General Environmental Verification Standard (GEVS) for GSFC Flight Programs and Projects in 2013, thermal verification testing has focused more on cycling and temperature range. This provided a robust program, yet allowed for tailoring for specific spacecraft configurations, launch vehicle, mission and level of risk accepted by the project. Goddard verification requirements have generally been developed for modular, low-risk observatories that can be tested at various levels of assembly (component/unit, subsystem, and system). More recently, higher risk tolerance missions and the introduction of smaller integral spacecraft (CubeSat, Nanosat, etc) with even higher levels of acceptable programmatic risk, have necessitated revisiting the thermal verification approach and levels of assembly to help projects meet commensurate cost and schedule, yet still maintain robust levels of thermal test verification. This paper evaluates the many GEVS thermal verification criteria and suggests which ones may be more appropriate to tailoring by these higher risk missions.