For more than ten years, a collaboration of European scientists has been producing simulations of the Gaia mission. These simulations range from detailed realistic simulated CCD images to large volume simulations of the Gaia telemetry.

The data of this decade of simulations has been used for many purposes: instrument design, data processing software testing and validation, prediction of mission performances, etc. Today the launch date is getting closer and the task of the simulator in the mission preparation will be wrapped up in a couple of years.

However, this is not the end of the story since the Gaia simulator can also be used for the preparation of the scientific exploitation of the Gaia data. In this talk we will present the simulator and its components, the data it can produce and the perspectives for the utilisation of this data during the mission, both for data evaluation and scientific exploitation.