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Thesis Abstract: Comparison of Design and Integrated Modeling Issues for Next Generation Ground-, Air- and Space-based Optical Telescopes

There is a fundamental conflict In applying many Systems Engineering techniques on complex systems in the design phase, it is this: that there is a tension between high fidelity (AKA trustworthy by experts) and highly flexible models of complex multidisciplinary systems. When using optimization or even evaluating the tradespace for trends across different designs, a systems engineer would want to evaluate a large range of architectures and designs, requiring a highly flexible model. Unfortunately, the types of models that encompass widely different architectures use estimations and guesses on several parameters, and therefore have a large error margin due to uncertainty. Therefore, in order to decrease the error, models gradually become more specific and less flexible. Developing high fidelity models for several different architectures would require a vast amount of effort and is untenable for complex opto-mechanical systems such as high performance telescopes. Instead of putting effort into improving fidelity of every aspect of the model, I propose that (1) certain aspects of each system impact system performance more than others, (2) that these aspects are unique to each type of architecture and (3) that by concentrating modeling efforts on these aspects, a more accurate model will result. This would facilitate a higher fidelity model overall, while still retaining flexibility appropriate for Systems Engineering analyses (multi-objective design optimization, pareto-front, sensitivity analysis, etc).

In order to test the hypothesis set forth above, I have chosen to concentrate on high performance telescopes which operate in three different domains, ground (G), space (S), and airborne (A) telescopes, each with their own architecture. While these telescopes all use reflective optics and have similar paths through which the science light travels (primary mirror, secondary mirror, tertiary mirror, science instruments), they incorporate very different architectures each with advantages and disadvantages.

PUBLICATIONS:
D. Howell and O. de Weck, Experimental Validation of Isoperformance Methodology, in Proceedings of the 9th Annual AIAA Symposium on Multidisciplinary Analysis and Optimization, Atlanta, GA, September 2002. AIAA Paper No. 02-5459

D. Howell, O. de Weck, and Carl Blaurock, A Three Step Multi-Configuration Model Tuning Procedure, SPIE Astronomical Telescopes and Instrumentation Conference, Glasgow, Scotland, June 2004.

D. Howell and O. de Weck, Multidisciplinary System Optimization of a Spacecraft Interferometer Testbed, MA AIAA-2004-4551 10th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, Albany, New York, Aug. 30-1, 2004