The Case for an Integrated Systems Approach to Extravehicular Activity

In this paper, we make the case for an integrated systems approach to the design and implementation of Extravehicular Activity (EVA). We define the EVA system as the set of hardware that enables EVA including the spacesuit, airlock, tools and mobility aids, as well as personnel and intangibles such as training, procedures, and software. In the context of planetary EVA, the system expands to include a rover, dust mitigation devices, and scientific instruments. The EVA system is in fact a complex, system-of-systems. The traditional approach to EVA system design optimizes each individual component, and may introduce inefficiencies into the system, generate logistics and supply management problems, and create hardware legacies that are hard to change and upgrade. We propose an integrated systems approach for advanced EVA system design that seeks to optimize the overall system, rather than just the individual pieces of hardware. The integrated systems approach also designs for uncertainty by anticipating change. By considering the complete system and allowing for change, the integrated systems approach incorporates both systems-of-systems thinking and spiral development. We examine the development of the Shuttle spacesuit and illustrate the challenges designers faced in adapting the suit to changing requirements. We conclude that due to the uncertain nature of exploration-class EVA, a system designed with the integrated systems approach offers significant advantages over the traditional design approach.