Modular Inflatable Composites for Space Telescopes

There is an ever-growing need to construct large space telescopes and structures for observation of exo-planets, asteroids in the main-belt and NEOs. Space observation capabilities could potentially be revolutionized by structures spanning several meters in size. Of particular interest are star-shades for imaging distant and high-resolution large aperture telescopes. Such structures efficient load bearing features and controllable precision surfaces. A promising approach to achieve high compaction for large surface areas is by incorporating compliant materials or gossamers. For most applications, gossamer structures require supporting stiffening structures to improve accuracy but this comes at the cost of reduced packing efficiency. Structural design strategies that maximize the use of gossamers are required to fully harness their potential. Our present work focuses on such a strategy using inflatable membranes. We introduce a methodology to investigate large structural assemblies of modular inflatable units stiffened pneumatically using inflation gas. Our work shows that such units assembled into composite structures can yield desirable characteristics. Further, modifying tension and geometry of such units could be used for localized tuning of the structure thereby reducing the need for rigid support structures. Our studies focus on two separate structural requirements. The first is efficient load bearing and distribution. Such structures do not need high precision surfaces but the ability to efficiently and reliably transmit large loads. Applications include deployable drag devices for atmospheric maneuvering. The second are structures with precision surfaces for optical imaging and high gain communications. A structural analysis strategy using discrete finite elements has been developed to simulate the assembled behavior of modular units. Our analysis leads to an understanding of the extent to which inflatables can be used to create large space structures.