Introduction of Research

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Leading Research for Future
Earth Observation System using Geostationary Orbit Satellites

With the conventional polar orbit Earth observation satellites, hour or day basis time is required from an observation request to the data distribution, and therefore they did not always meet requests for urgent observation in times of disaster. Using geostationary orbit (GEO), we can make such instantaneous satellite observation possible. One of the largest technological challenges was to implement a large-scale telescope to keep useful ground resolution over the large disaster area from altitude of 36,000 kilometers.

In this study, we plan to apply the ground-based telescope mature technologies, e.g. the active optics system adopted by the Hawaii Subaru Observatory and the cutting-edge segmented telescope “Seimei Telescope” of the Okayama Astronomical Observatory in Japan, to materialize a large-scale space telescope. The target diameter of main mirror is 3.6 meters, which is more than double that of conventional optical spaceborne imagers. This achieves the ground sampling resolution of approximately 7 meters from GEO at nadir and an on-demand image/video Earth observation system within 30 minutes from the request. The Earth observation with these technologies, hence, can contribute to provide images instantaneously to end users, and to mitigate disaster damages.

 

The Value of Our Research

Geostationary orbits located at the altitude of 36,000 kilometers is several dozen times higher than that taken by many other Low Earth Orbit satellites, of which altitude is approximately 400 to 700 kilometers. Naturally, it requires much more high level of every sensor performance including larger main mirror diameter of telescope.

In this study, we do not only make improvements to conventional technologies, but also adopt cutting edge technologies such as segmented telescope technology. Our innovative R&D activities on Earth observation systems will strengthen the technical basis over the next several decades and create and enlarge new possibilities for future missions.

Our research area is interdisciplinary and especially focused on following three themes; (1) research on Earth observation systems, including geostationary orbit satellites, (2) research on optical imager systems based on segmented telescopes, and (3) research on infrared imager systems.

 

Research Goals

Research on Earth observation systems
Geostationary Earth observation
system concept
  • Studying use cases of observation data, including video data and post data process algorithms
  • Studying a GEO Earth observation system based on MBSE (Model Based Systems Engineering)
    ✔ Consistent design technology of an observation
      system from the development, testing, launch,
      and operation of satellite system to data delivery
      to users
  • Studying high-precision quiet satellite attitude systems (control, determination, stability)
 
Research on optical imager systems
Prototype of Cordierite ceramics mirror
  • Studying φ3.6-meter segmented telescope system (optics/thermal/structure)
  • Studying space-borne segmented mirror (high precision, high specific stiffness, and high thermal stability)
    ✔ Large-scale segmented optical mirror made by
      Cordierite ceramics that have superior material
      properties on specific-stiffness and thermal stability
  • Studying active/adaptive optics for segmented telescope system (wave-front measurement and compensation)
 
Research on infrared imager systems
  • Studying large-scale and high-sensitivity Type-II superlattice based infrared detector arrays
  • Studying low-microvibration and long-life mechanical coolers