Enhancing NSS System Engineering Analysis through Value-Centric Design Methodology

Abstract

In the traditional space mission systems engineering process (SEP), candidate architectures are evaluated by comparing multiple dimensions of performance against cost. Many of the key decisions within this process focus on trading dierent performance parameters at a xed cost, or dierent levels of performance against varying cost. The selected system architecture is generally that which produces an acceptable level of performance at lowest cost. The SEP also generally only considers a small number of alternative designs, providing a limited perspective on what could be a much larger tradespace. The traditional process has worked well in the past, producing designs that optimized cost for a xed level of performance. However, the traditional process is based on many assumptions, some explicit and some implicit, regarding uncertainty, change and the domain of control. Many factors once treated as static or having an acceptably slow rate of change are now changing at rates that are incommensurate with the current rates of execution of the SEP. The traditional process also does not capture the reality of the uncertainties that impact programs during development and deployment. We describe an approach to space mission systems engineering that incorporates changeability and robustness in order to address uncertainty and change. We discuss this valuecentric design methodology (VCDM) and proposed framework for addressing changeabiliity and robustness under uncertainty. We refer to this approach as the value-centric systems engineering process (VCSEP). VCSEP is a dynamic approach to capturing stakeholder value value over time by applying multi-attribute utility analysis to the analysis of candidate system architectures and their associated costs. We describe a framework for VCSEP and some of the challenges to realization. It should be emphasized that the VCSEP framework does not provide a \turn-the-crank approach to systems analysis. Rather the framework species a process for engaging the system stakeholders, architects and designers, with the ultimate goal of providing the decision makers with the \best set of alternatives from which to make a selection on which system to build.