Deployable structures are structures that can change their shape and size (automatically) from a compact configuration to a large, open configuration. They could be described as structures capable of being unfolded, disassembled, unwound or even separated, which gives an insight into the diversity of these structures and what is meant by the term 'deployable'.
The topic is almost as old as spaceflight itself. Such a concept was used for the first time in the 1960s, as a gravitational stabilisation boom. Nowadays, these structures are used for essential tasks in spacecraft and include solar panels, radiators, antennas and various kinds of masts used for a variety of things. Flexible and very light structures, the so-called Gossamer structures, and their technical capabilities have been exhaustive. Future applications of large, thin-layer photovoltaic surfaces, drag sails, solar sails or membrane antennas will be achieved with these structures.
In the area of large deployable structures, the department of Mechanical and Thermal Systems is developing technologies for the production, stowing and deployment of membranes and their supporting structures. These structures can be used for increasing the surface area so that satellites can be deorbited from a near-Earth orbit, creating a large solar panel using thin-layer photovoltaics, and solar sails as an alternative propulsion solution. To develop these structures, the department uses a vacuum table to produce a sail and a custom-made deployment test facility located in the clean room area ISO-8 at the Institute. This ensures the necessary level of purity for flight missions and tests in a thermal vacuum. Furthermore, manufacturing routines are developed and implemented in accordance with space standards.
The Department has developed a verification strategy for large, deployable membrane structures – from the onset of developing the technology through to qualifying it for use in space – and this strategy has been used successfully in a variety of DLR projects (Gossamer-1, Huge Solar Array), and ESA projects (ADEO, Deployable Membranes). In terms of photovoltaics, the focus is on applying commercial, thin-layer photovoltaics to the top of deployable membranes using suitable contacting and adequate harnessing as well as on studying the usability of certain materials and their degradation.
