Future remote sensing systems

This paper presents the results of a study carried out for ESA by Alenia Aerospazio, regarding the identification the future (2005–2010) Earth Observation (EO) market, requirements, concepts, architecture and technologies. The EO market expansion seems principally driven by the availebility of high revisit time data and their fast delivery to the Users. If 6 hours revisited data can be disseminated, a market of 600–2000 MECU/y was estimated by ESYS for new business sectors, like: agriculture, iceberg mapping and forecast, oil spillage detection, all weather/time mapping, disaster detection and monitoring, pollution control. Alenia Aeropazio has derived from this market analysis a set of mission requirements which foresees: global access time lower than 7 hours (i.e. from user request to processed data availebility), all weather/ day-night observation capability, high spatial resolution images ( The implementation of those challenging requirements is performed by small satellite constellations based on both SAR and optical sensors. The activity was performed together with the University of Naples. The SAR constellation consists of 10 satellites in two orbit planes while the optical constellation has five satellites. Because the target weight for the satellite design is constrained to 300 kg, new technologies are adopted for satellite design including: electric propulsion, autonomous navigation, advanced power generation, integrated on-board electronics, low weight materials. The SAR uses the Ku frequency to reduce the antenna size and to achieve the one meter spatial resolution without antenna beam steering in the azimuth direction. Furthermore with low antenna dimensions single pass Interferometry or two antennas MTI can be implemented. Integrated optics and micro technology are introduced in the optical sensor. Optical 3-D images are achieved by satellite tilting on the pitch axis, while Earth rotation is compensated by rotating the yaw axis. Novel compression techniques permit reduction of the data rate by a factor 10 for SAR and 50 for optical images. The possibility to use GEO for optical high resolution sensors was explored and an innovative concept was outlined, based on a multi-aperture concept. The on-ground segment is supported by automatic receiving stations which receive the satellite data, process them and disseminate the products through a multimedia GEO satellite whose definition is another part of the ESA study. Finally, system cost is estimated and compared to the envisaged revenues.