European large deployable antenna: development status and applications

This presentation describes the development and the results of the qualification activities of the 12m unfurlable Reflector Assembly of the Large Deployable Antenna (LDA), jointly developed by the Prime Contractor: Thales Alenia Space Italia and several Partners, under an ESA contract. The qualification campaign will be finalized within the year 2007, opening near-term opportunities for space applications relying on a European technology. The Russian subcontractor NPO EGS and RSC ENERGIA will be designing, manufacturing and test qualifying the Reflector and hold-down system (LHS) of the Reflector. The west European countries subcontractors have designed important components like a big mechanical hinge, a trimming mechanism and the antenna hold-down. The LDA system requires four hinges (ADB) (by HTS - Switzerland) to deploy the limbs and to locate the opened antenna in the selected position in order to have the proper distance from the satellite and the RF feed. A reflector trimming mechanism (RTM) (by SENER - Spain) is installed between the tip of the deployed antenna limbs and the Reflector. This mechanism is used to trim the Reflector, recovering the thermo-elastic distortion. Two big hold-down (AHD) (by STEYR MAGNA-Austria) have been designed to hold the limbs of the Arm during launch. The presentation illustrates the LDA development phases, starting from the requirements definition, passing to the antenna configuration description and going throughout the performed design analyses which have allowed to hold the successful CDR's of all the LDA components: The presentation continues with a description of the qualification of all the LDA components already fully qualified and the Reflector assembly under test at the moment. Particular emphasis is dedicated to the Reflector assembly deployment and the measurement of the reflector surface in consequence of the mesh tuning activity as well as to the PIM test. Comparison between the test results and the analysis predictions is shown, with particular care about the prediction of the RF performance based on the mesh surface measurement. The presentation also dedicates a section to the Flight Experiment (FE), which is a follow on activity of the LDA qualification, with the objective of the in orbit verification of the following performance: (i)LDA deployment, (ii) reflector mesh surface accuracy and stability (iii) PIM measurement in the orbital environment (iv) RF characterization by means of a Telecommunication experiment in L and/or S band (v) assembly and operation in LEO of a Synthetic Aperture Radar in L band (TBC). The final section of the presentation provides an overview of the LDA possible applications at system level.