Date of Award

Spring 1-1-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Aerospace Engineering Sciences

First Advisor

David M. Klaus

Second Advisor

Ryan P. Starkey

Third Advisor

Jean N. Koster

Abstract

The research efforts in this dissertation are focused on reducing uncertainty in the conceptual design phase through a process of establishing a minimum functionality baseline before trading Safety and Operability in proposed spacecraft configurations. The challenge in human spacecraft development is how to combine the parts into a working design that complies with many requirements for top level mission objectives, safety, and mission success. The design methodologies presented here provides designers and decision makers with additional methods that provide an overall view of candidate design concepts. This work establishes a definition for a minimum functional design and is the first to group the fundamental mass parameters of a human spacecraft in the categories of Physics, Physiology, Safety, and Operability. The minimum functional baseline configuration described in this work is different from previous approaches because it eliminates the bias toward a minimum set of requirements. The amount of Safety in the spacecraft is the mass dedicated to safety through similar or dissimilar redundancy, safety components, margins, and dispersions. The amount of Operability in the spacecraft is the mass used to perform mission objectives and make functions easier or efficient. Because human spacecraft are highly coupled systems, the introduction of mass in one subsystem has downstream effects on other subsystems that are not easily recognized by designers and the use of rapidly reconfigurable prototypes allows designers and multidisciplinary teams to utilize Boundary Objects as a means of communication for maturing designs. The mass addition process coupled with the minimum functionality approach creates a tradespace of spacecraft configurations and provides designers with an overall view of how various levels of Safety or Operability will affect the overall spacecraft mass. The decisions made in the conceptual design phase are critical to the success of the program and uncertainty can lead to unnecessary redesign in later phases. The previous methods can be combined into a conceptual design process that couples easily with typical industry approaches to human spacecraft development. The use of minimum functionality as a precursor to more conventional approaches allows the spacecraft configuration to take shape before detailed CAD and higher fidelity analyses.

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