The future GAIA mission, planned for December 2011, is a European Space Agency (ESA) project aimed at generating the largest known map of the galaxy. By means of two telescopes and their instruments, GAIA will observe and catalogue 2,000 million stars in the Milky Way. Furthermore, GAIA is expected to discover hundreds of thousands of celestial objects and to provide further proof on relativity and cosmology in general. SENER, one of the founding members of the Aerospace Cluster, HEGAN, is participating in the said project as supervisor of the GAIA shield, whose mission it will be to preserve the instruments at low temperatures and ensure the thermal stability of the optical elements. SENER has successfully completed several phases of the GAIA shield, HEGAN, Basque Aerospace Cluster, contributes to ambitious ESA Project
Furthermore, SENER will be in charge of the telescope’s secondary mirror positioning mechanism, which connects the reflecting mirror to the optic bank, known as the M2M Subsystem. The GAIA shield is a structure with a diameter of 11 meters, with 12 identical frames that deploy simultaneously and that hold two thermal blankets installed in parallel. The blanket facing the sun will reflect the sunlight, only allowing part of the solar energy to reach the protected area where the satellite and instruments will be located.
The deployment mechanisms, also by SENER, include a synchronization system, flexible supports that fix the protecting elements to the framework to absorb the tension generated by differences in temperature and a deployment system based on adjustable springs.
In connection with this deployable shield, SENER has surpassed several important milestones: in March 2007, it completed the PDR (Preliminary Design Review) phase required for the manufacture of the assessment model. The model consists in one fourth of the full shield, i.e., three sections of the twelve that will comprise the complete shield. In October 2008, it delivered the subsystems for the assessment model and, in December of the same year, the assessment model TRR (Test Readiness Review).
Furthermore, over the last year, SENER has completed assessment tests on the subsystems: mechanisms, structures and thermal blankets. The mechanisms, for which this HEGAN Cluster company is responsible have successfully passed the assessment tests and have proven they work correctly after going through vibration and thermal vacuum tests. In turn, the structures, manufactured by RUAG Switzerland, have been accepted by SENER after extensive verification tests, during which the engineering company has checked their dimensional stability and load capacity features.
The structures, weighing four kilograms each and measuring three meters high by one meter across, are made of ultra-fine carbon fiber tubes in order to reduce weight. Finally, SENER has completed the relevant dynamic tests on the blankets, which were manufactured by RUAG Austria under contract by SENER and which have also passed their assessment tests. These tests were performed on reduced scale samples with a view to verifying the material’s capacity to stand the conditions expected throughout the life of the satellite.
At present, SENER is completing the assembly of the assessment model at the Aerospace Technology Centre (CTA), which also belongs to the HEGAN association, in a clean room that has been especially adapted for the GAIA shield and its components. The first tests on the operation of the shield have been performed without the thermal blankets in order to adjust the mechanisms. With this assessment model, SENER plans to perform a number of tests to prove compliance with the necessary technical specifications required for the success of the mission.
