Proceedings Article | 12 July 2008
KEYWORDS: Mirrors, Finite element methods, Integrated modeling, Acoustics, Silicon carbide, Space telescopes, Manufacturing, Space mirrors, Matrices, Lightweight mirrors
The future of space telescopes lies in large, lightweight, segmented aperture systems. Segmented apertures eliminate
manufacturability and launch vehicle fairing diameter as apertures size constraints. Low areal density,
actuated segments allow the systems to meet both launch mass restrictions and on-orbit wavefront error requirements.
These systems, with silicon carbide as a leading material, have great potential for increasing the
productivity, affordability, and manufacturability of future space-based optical systems.
Thus far, progress has been made on the manufacturing, sensing, actuation, and on-orbit control of such
systems. However, relatively little attention has been paid to the harsh environment of launch. The launch
environment may dominate aspects of the design of the mirror segments, with survivability requirements eliminating
many potentially good designs. Integrated modeling of a mirror segment can help identify trends in
mirror geometries that maximize launch performance, ensuring survivability without drastically over designing
the mirror. A finite element model of a single, ribbed, actuated, silicon carbide mirror segment is created, and is
used to develop a dynamic, state-space model, with launch load spectra as disturbance inputs, and mirror stresses
as performance outputs. The parametric nature of this model allows analysis of many geometrically different
mirror segments, helping to identify key parameters for launch survival. The modeling method described herein
will enable identification of the design decisions that are dominated by launch, and will allow for development
of launch-load alleviation techniques to further push the areal density boundaries in support of the creation of
larger and lighter mirrors than previously possible.
