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Recent advancements in science have led to an increasingly sophisticated understanding of the many ways in which humans benefit from environmental systems. These benefits, termed Ecosystem Services, are sparsely characterized in education literature, but were included in the most recent iteration of US national science standards: the Next Generation Science Standards (NGSS). In this paper, we introduce the concept of Ecosystem Services and discuss why it is emerging as an important idea to teach. Specifically, we present a definition and set of big conceptual ideas about ecosystem services developed using a Delphi technique: a method that uses repeat survey of a panel of experts in a domain, to reach a consensus about important ideas. Using the central ideas that emerged during this study, we developed a refined model of coupled human-environment systems that articulates multiple human populations as embedded within ecosystems, connected to these ecosystems near and far, and benefiting from the resources and conditions provisioned by these ecosystems. We discuss the implications of this model to future education research, as well as to future revisions of Disciplinary

Completion of the final Space Shuttle flight marks the end of a significant era in HumanSpaceflight. Developed in the 1970's, first launched in 1981, the Space Shuttle embodies many significant engineering achievements. One of these is the development and operation of the first extensive fly-by-wire human space transportation Guidance, Navigation and Control (GN&C) System. Development of the Space Shuttle GN&C represented first time inclusions of modern techniques for electronics, software, algorithms, systems and management in a complex system. Numerous technical design trades and lessons learned continue to drive current vehicle development. For example, the Space Shuttle GN&C system incorporated redundant systems, complex algorithms and flight software rigorously verified through integrated vehicle simulations and avionics integration testing techniques. Over the past thirty years, the Shuttle GN&C continued to go through a series of upgrades to improve safety, performance and to enable the complex flight operations required for assembly of the international space station. Upgrades to the GN&C ranged from the addition of nose wheel steering to modifications that extend capabilities to control of the large flexible configurations while being docked to the Space Station. This paper provides a history of the development and evolution of the Space Shuttle GN&C system. Emphasis is placed on key architecture decisions, design trades and the lessons learned for future complex space transportation system developments. Finally, some of the interesting flight operations experience is provided to inform future developers of flight experiences.

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