Adaptive thin shell space reflectors

Abstract

This chapter begins with a general discussion of the future needs for large space reflectors (lighter, larger, foldable), leading to the concept of adaptive thin polymer shell reflector. Next, a comparison between an adaptive plate covered with a layer of piezoelectric material and a similar spherical shell is conducted to point out the fundamental difference of behavior of a shell with double curvature (because of the large hoop stiffness). A multi-electrode spherical shell is considered, and the relationship between the surface figure error and the electrode size, the shell curvature and thickness is derived (for various Zernike modes). Then, the control of adaptive shell involving a very large number (thousands) of independent electrodes is examined and, based on Saint-Venant’s principle, a hierarchical control approach is derived to solve the ill-conditioning of the Jacobian. Finally, petal configurations are considered as a way to increase the controllability and improve the folding capability. The chapter concludes with a reference list.