Systems engineering uses quality attributes known as “ilities” to validate a target architecture. Space agencies call for unified, customised, and updated software development methodologies (SDM). Affiliated primes have documented conflicting ilities across standards. Ilities can be used to verify selected mission constraints. Identified desired ilities inputs improve the functional design. A systematic qualitative review collated previous ility classification articles. This research applied grounded theory to develop a collection of 345 ilities as a unified taxonomy based on prior classification literature and operational standards. Reliability, scalability, and adaptability are within the top 10% of 161 unique ility classes. In total, the classes contain 668 ilities. Ilities are split between small satellite systems and smallsat software architecture—an aggregate review identified inputs for the desired ilities. A conceptual schema is presented for each ility to show inputs for the development of future calculations.