[SatNews] Deployment testing of the Gaia Flight Model Deployable Sunshield Assembly....

....has been successfully completed in preparation for the spacecraft mechanical test campaign. Gaia will perform micro-arcsecond astrometry of over one billion objects in the Milky Way and beyond. In order to achieve the required measurement precision, the spacecraft and its instrument payload must be shielded from direct sunlight and maintained at a stable, low temperature. Any thermal instability at the level of a few hundreds of µK or more could affect the final accuracy of the measurements. The thermal stability of the Gaia spacecraft will largely be determined by the Deployable Sunshield Assembly (DSA), which will protect Gaia and its instruments from illumination by the Sun. Once deployed, the sunshield will be ~10.2 m across and have an area of ~75 m2.

SENER (Spain) is responsible for the development and manufacture of the DSA. The design was validated by thermal vacuum and thermal balance testing of the Qualification Model (QM) at ESA's European Space Research and Technology Centre (ESTEC) in July 2009, and by further deployment testing of the QM in the thermal vacuum chamber at Intespace, Toulouse, during August 2011. The Flight Model (FM) DSA has already undergone two deployment tests, one at SENER upon completion of manufacturing and one in Astrium Toulouse following thermal cycling. During October 2011, the FM DSA was formally delivered to Astrium (France), the Prime Contractor for the spacecraft, and integrated with the FM Service Module and Thermal Tent and a mass-representative model of the payload module. Once integrated, the first deployment test of the DSA mounted on the spacecraft took place in Astrium on October 21st. This test demonstrated correctness of alignment, confirmed the deployment functionality and verified the flatness of the deployed DSA. The spacecraft was then moved to Intespace in Toulouse for its mechanical test campaign.