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AIAA 2021-4015
Session: Space Architectures: Advanced Technologies for Exploration
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Space architects and mission planners have long managed the compromise of maximizing the capability of a space asset while staying within the lift capability and payload bay size of available launch vehicles. Alternate approaches include breaking up a space asset into multiple smaller elements to be launched separately or keeping the asset as one large payload to be launched on a single launch vehicle. Separated elements may carry independent redundant functions such as propulsion, control, or communication, which would be required to operate in space and enable a rendezvous of two elements. Larger elements, pre-integrated and checked on the ground, introduce some differences and efficiencies. These are typically more reliable, with fewer interfaces, less costly overall and simpler to deploy. Different approaches of integrated vs. separated payloads are assessed within this paper, with consideration to spacecraft functions answering a set of basic ground rules. Simple architectures of separated and integrated spacecraft are developed to a level of fidelity that allows first-order comparisons. Examples include Apollo elements and the NASA staging node for lunar missions, to be placed in cislunar orbit, the Gateway. Ultimately, this paper presents a crewed Mars transit scenario, with a discussion of the differing integration approaches of spacecraft and payload elements. Larger, fully-integrated payload and spacecraft elements may carry a higher up-front cost as compared to multiple smaller separated elements, while separated multi-element solutions are often characterized by a higher overall total costs spread over longer time. Striking the right balance between cost, complexity, schedule and operational efficiency will be a critical task for architects of deep space missions.