The Gaia mission. Pulsating stars with Gaia
  Gaia is a cornerstone mission of the European Space Agency (ESA) selected in 2000, with a target launch date of 2011. The Gaia mission will perform a survey of about 1 billion sources brighter than V=20. Its goal is to provide astrometry leading to parallaxes, proper-motions and positions. Astrometric data are complemented by multicolour photometry and a spectroscopic instrument (up to V=17 mag) to provide astrophysical parameters (as effective temperatures, surface gravities, metallicities) and radial velocities. The survey will have multi-epoch observations allowing a detection of the variable sources; objects will be measured as a mean 80/100 times over the 5 year mission length in the two instruments on board, the Astro-/Spectro-instruments respectively.   The data processing of the mission is a major challenge: as a first step working groups on different themes were created and have been active. One working group has been dedicated to variable stars. A consortium for the data processing is currently being created, the Data Processing and Analysis Consortium.   Though several aspects of the Gaia mission are under possible changes, we review some activities related to the mission in the perspective of pulsating stars. 
Laurent Eyer