The EDR Value Model for the NSOSA Decision Process

The National Oceanic and Atmospheric Administration (NOAA) has conducted a study, the NOAA Satellite Observing System Architecture (NSOSA) study, to plan for the next generation of weather satellites. This study has been an opportunity to design a modern architecture with no pre-conceived notions regarding instruments, platforms, orbits, etc., but driven by user needs. The user needs within the study were modeled by the Environmental Data Record (EDR) Value Model or EVM. The EVM represented a compromise to satisfy a diverse and potentially conflicting set of study needs. First, it had accurately capture the full range of needs addressed by satellite observing system data. The needs capture must be valid through the NSOSA epoch that begins in 2028 and extends through 2050. Second, it had to be of complexity low enough to allow quantitative assessment on potentially 100 alternative satellite architectures (the study eventually constructed nearly 100 alternatives). Third, the value model had to be alternative neutral. It needed to capture the advantages and disadvantages of both legacy oriented and radical alternatives. Fourth, it needed to have solid traceability to documented needs in different time epochs and its results must be able to withstand the external scrutiny inevitable on any study that intends to guide billions of dollars of expenditure.

The EVM built in response to these goals was constructed on functional objectives built from abstracted sensor data records coupled to selected non-functional or “strategic” objectives. The overall framework was drawn from Multi-Attribute Utility Theory (MAUT) and configured to allow quantitative results in the final comparison phase. 44 objectives were captured with 1 to 10 measures of performance per objective. Each measure had three levels of performance, from “Study Threshold” at the bottom to “Maximum Effective” at the top. The sets of objectives and their performance levels were set and managed by the Space Platform Requirements Working Group (SPRWG) a group formed with broad stakeholder representation.