As part of the Clean Space roadmap, ESA is researching and developing technologies that will prevent the formation of space debris. The Code of Conduct stipulates that satellites must be deorbited within 25 years of passivation at the end of their useful life.
The aim of the ESA project Deployable Membranes is to research suitable materials for ultra-lightweight, deployable sails, as well as the stowage and deployment of the sails, which will enable the passive re-entry of spacecraft from a low Earth orbit within 25 years. Sail development will be used in the ESA project, ADEO, for the construction of a demonstrator.
At the DLR site in Bremen, strategies are being developed and implemented for stowage and deployment, and all tests are being carried out in accordance with the verification strategies for large and deployable structures developed by the Institute of Space Systems. Research into solar sails, carried out over the years by DLR, and in particular findings from the DLR project, Gossamer-1, are being used as a basis for this. In this regard, the Institute has a vacuum table, which can be used in the production of the sail; a thermal vacuum chamber for simulating the climb experienced by aircraft during launch as well as the conditions during the operational phase; and a self-developed test facility for large deployable membrane structures. The testing of deployable membranes in vacuum is being made possible thanks to the Space Simulation Chamber (Weltraumsimulationsanlage; WSA).
Another research area is the ageing of membrane materials, which must be stowed away in space for 20 years, to be deployed after 25 years, and be in a safe and working condition. DLR is coordinating the ageing tests, which will consist of radiation tests ranging from solar radiation to vacuum UV (VUV); tests with atomic oxygen, and finally, tests on the properties of the materials. During these tests, undamaged material samples, as well as samples that have been damaged in advance by folds or previous tests, will be examined. The DLR-operated Complex Irradiation Facility will be used for the ageing tests conducted as part of the wider radiation testing.