Tradespace Exploration for a Parameterized Modular Optical Space Telescope (MOST)

Abstract

The Modular Optical Space Telescope (MOST) project is a design tool that allows rapid generation and analysis of many unique space telescope realizations. The project uses a parametric integrated model to quantitatively analyze many dierent architectures during the conceptual design phase. MOST aims to include advanced concepts and technologies such as lightweight, deformable optics, dynamic wavefront control, and low-cost segmented mirror systems. Traditional optical performance metrics are considered alongside programmatic metrics such as cost, robustness, and mission operations, permitting an examination of these conflicting requirements at the very beginning of the project. The model has been substantially updated to include new technologies, control, and performance metrics, and the trade studies continue to provide insights into determining favorable space telescope architectures. urrent space telescopes are reaching their limits in terms of size, cost, and performance. Future systems will have larger aperatures with increasingly tight performance requirements, with line-of-sight (LOS) jitter on the order of milli-arcseconds and wavefront error (WFE) on the order of nanometers. At the same time, lower mass and lower cost systems are desired. This creates an implicit conflict for currently designed systems, thus new technologies and telescope types must be developed and implemented. Technology possibilities for these new systems include deployable mirrors or sparse apertures, structural control, and active optics. Sparse apertures and deployable optics can be deployed on orbit, eliminating the launch fairing diameter as an aperture size constraint. Also, the smaller, identical mirrors used in sparse apertures are easier and less expensive to manufacture than large monolithic mirrors. Structural control can provide a means to achieve better performance with a less massive system by counteracting the flexible dynamics of the lightweight system. Active optics can help to meet the strict performance requirements. A fast steering mirror can correct for LOS jitter, and wavefront sensing and mirror shape control can rectify both thermal and dynamic distortions of the primary mirror. These and other technologies provide a promising path to meeting both the performance and systematic requirements of future space telescopes. The challenge is in determining which combinations of technologies create favorable architectures. It is important to explore the entire tradespace of possible designs to ensure that superior designs are not overlooked. In order to assist with these important decisions and tradespace exploration, the MOST project has created a parametric modeling technique to consider the implications of design decisions during the conceptual design phase. 1,2 In the past, simple models, along with engineering judgment, have been used in the conceptual design phase where key design decisions were made. During the preliminary design phase, detailed models of the single point design were built and analyzed. If the requirements were not met, then another point design was chosen and modeled. This strategy works well if the system is based upon heritage designs and performance can be adequately predicted. However, with the addition of new technologies, there is no guarantee that the chosen point design would meet the requirements, and if the design does meet requirements, there is no assurance that it is an optimal design. Therefore, the MOST project uses a parameterized model to quickly and automatically generate and analyze many designs during the conceptual