Lightweight inflatable solar array

Abstract

A lightweight deployable solar array wing in the 200-1000-W range has been developed, on the Inflatable Torus Solar Array Technology Demonstration (ITSAT Demo) Project. The power density of a flight unit could be as high as 93 W/kg for a 200 W-class wing, including structure and deployment mechanisms. In Phase I, a proof-of-concept torus and array were constructed and deployed in the laboratory. During Phase II, a revised torus and array were constructed and tested at L'Garde and the Naval Research Laboratory. The qualification tests included random vibration, deployment in a thermal vacuum chamber, natural frequency determination, and thermal cycling. The flight design uses 2-milthick crystalline silicon cells on an atomic oxygen-protected flexible Kapton film substrate folded accordion style for stowage. The support structure is a rectangular frame comprised of two cylinders (which are inflated then rigidized), the array stowage box, and its cover. The cylinders, flattened, folded and stored for launch, are deployed by inflating with N2 and rigidized by straining the cylinder laminate material controllably beyond the elastic limit. The engineering protoflight array was designed for optimum power density but, because of availability, some of the components came from excess production runs. Because of this, the actual power density of the test article was 59 W/kg, or 36% lower than the baseline flight array. However, using components as designed, the projected 93 W/kg can be achieved. Because of a simple deployment mechanism, the cost of an ITSAT-type solar array is about one-half to two-thirds that of competing systems.