We present a software tool that allows to perform end-to-end simulations of a space mission, which is a quite new approach in remote sensing. It addresses the need of engineers and scientists to better understand the new missions whose complexity is increasing. This end-to-end simulation tool allows far before the launch to assess the performance of the overall system including the instrument, the satellite platform and the ground processing algorithms. It is of great help in the frame of space mission design and analysis and helps understanding how the performance of all or part of the system contributes to the mission performance. The space mission simulated in this work is that of the Medium Resolution Imaging Spectrometer (MERIS) developed by the Space European Agency whose main objective is the remote sensing of ocean colour. We use the simulator to evaluate the signal dynamics at sensor entrance, to compute the sensor radiometrie resolution needed to satisfy the mission objectives and to study the signal sensitivity to small variations in platform attitude. Then we study the influence of the quality of the modelling of the reflection effects at the sea surface upon the ocean colour retrieval. We show that the uncertainties, due to a lack of precision in modelling of surface effects and to the uncertainty in the wind speed induce errors on the marine signal that can be greater than the mission expected accuracy.
