Geostationary Earth Observation Satellite with Large Segmented Telescope

To mitigate human damage by a catastrophic disaster, such as Great East Japan Earthquake and Tsunami happened in 2011, a quick satellite observation and data distribution are the keys to recognize damaged area and make plans to rescue. Geosynchronous orbit is the best solution to provide an instantaneous observation from the occurrence of the disaster. However, we could not materialize such satellite system for its large and heavy telescope considering its reasonable ground resolution requirement, such as "less than 10m". Recent progress of and segmented mirror telescope for astronomy on the ground, might make it possible to have such design solution. A system concept study was carried out by JAXA. We designed 3.6m diameter segmented telescope using active/adaptive optics to control wavefront error. The target ground resolution might be 6-8m with visible panchromatic band at Nadir. Also, the target observation latency is less than 30 minutes from receiving requirement to saving geometrically corrected data on server. The large telescope system will be mounted on current satellite bus or all electric propulsion bus and launched by new H3 Launch Vehicle. We are planning for three years' test campaign using partial model of the active mirror system.