Optical sensors and data transmission

After a brief review of the SPOT system, as an example of utilization of an optical sensor, the paper briefly analyses the future optical sensors in low Earth orbits. The emphasis is put on the implications on data transmission and dissemination. The increasing demand for improved spatial and spectral resolutions have generated new concepts of sensors, such as imaging spectrometers. Two classes of instruments are envisaged as regard to the data transmission problem: instruments for global and continuous Earth monitoring and instruments for local high resolution applications. After a review of the current direct to ground link capability and its evolution, and a review of the recorders technology capability and limitation, some of the benefits from a data relay satellites system are presented