The European Space Agency's LISA mission study: status and present results

The European Space Agency is currently pursuing a comprehensive industrial study of the complete LISA mission within a contract awarded to Astrium Satellites GmbH in 2005. The study is in its final phase and has developed a consolidated mission and payload concept. The feasibility and robustness of the mission concept has been confirmed. The mission performance and the resulting technical requirements have been investigated in detail and converted into an optimised technical design for instrument, spacecraft and constellation. Designed mainly in order to cope with the dynamics of the LISA constellation, three suitable instrument architectures have been defined: (1) two independently rotating optomechanical/reference sensor assemblies serving the adjacent interferometer arms with stationary laser beam path inside, (2) one fixed opto-mechanical and two reference sensors assembly with telescope in-field pointing of laser beams, (3) one fixed opto-mechanical assembly with telescope in-field pointing of laser beams and one active reference sensor. The final baseline selection will be guided by mission robustness and reliability, technical complexity, cost and engineering budgets.