Estimation of the MTF of a satellite imaging-system from celestial scenes

The modulation transfer function (MTF) is commonly used to characterize the quality of electro-optical imaging systems and in particular those on board remote sensing satellites. Measurements of the camera MTF are made on the ground prior to launch, but evaluation and monitoring of the complete system performance are also required while the satellite is in orbit. In this work a new method to estimate the MTF in orbit was developed. The MTF was derived from celestial scenes (stars), which are ideal light point sources, imaged with the ErosB satellite. By following the MTF through time, this method was proven to be a good method to monitor the imaging system performance in space.