GoSolAr DLRs Gossamer Solar Array Conceptual Demonstrator

Abstract

The power demand for future satellite applications will continue to rise. Geostationary telecom-munication satellites currently approach a power level of up to 20 kW. Future spacecraft will provide more transponders and/or direct mobile-satellite services. Electric propulsion is increas-ingly used for station keeping, attitude control and GEO circularization. Interplanetary missions already use kW-range electric propulsion. Space Tugs are studied for several fields. Suitable en-gines require 100 kW or more. The envisaged use of such engines and the operation of future GEO satellites lead to a renewed interest in large, deployable and ultra-lightweight power generators in space. Within the GoSolAr (Gossamer Solar Array) activity, DLR develops a new photovoltaic array technology for power generation. It is based on the DLR Gossamer approach using lightweight, deployable CFRP booms and a membrane consisting of thin-film CIGS photovoltaics generators and the necessary power harness. The booms are arranged in a crossed configuration with a cen-tral deployment unit. The photovoltaic area is composed of one large square membrane with double folding using two-dimensional deployment. Even though the efficiency of thin-film photovoltaics is currently only about 1/3 of that of con-ventional photovoltaics, a membrane based array can already equal or achieve better mass/power ratios. A 50 kW array requires an area of approximately 20 m x 20 m. In a first step, DLR devel-ops a fully functional 5 m x 5 m demonstrator partially covered with thin-film photovoltaics and considering scalability aspects. Space compatible thin-film photovoltaics need to be selected and tested. They are integrated on standardized generator modules that will be assembled into a large, foldable and deployable membrane. A controlled deployment of structure and membrane, and a sufficiently stiff support structure for operation are key development topics. We present the conceptual design of the GoSolAr deployment demonstrator, the main require-ments, preliminary technical budgets, the development strategy and first experimental results. An overview will be given on the selection and the maturity of the key technologies and subsystems, such as deployable membrane with integrated photovoltaic generators; deployable CFRP booms including deployment mechanisms as well as electronics concept for operation and photovoltaics characterization. Furthermore, an overview of the first manufactured breadboard models and their testing will be presented, e.g. combined testing of booms and mechanically representative generator arrays to evaluate deployment and interface forces for the preliminary design.