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Abstract

Feasibility Study of the Satellite System for the Japanese Future Altimetry Mission

Mr Kenichiro NIGO(1), Mr Kobayashi TAKASHI(1), Mr Naoki MIYASHITA(1)

(1) Japan Aerospace Exploration Agency, Japan

Session theme: Others (Posters only)

  • poster

    Abstract

    The Japan Aerospace Exploration Agency (JAXA) is conducting a conceptual study of an altimetry mission for marine environment monitoring, fishery, etc. JAXA?s internal conceptual study team names the mission COMPIRA (Coastal and Ocean measurement Mission with Precise and Innovative Radar Altimeter) and its main sensor SHIOSAI (SAR Height Imaging Oceanic Sensor with Advanced Interferometry). The sensor is a Cross-Track Interferometric Synthetic Aperture Rader (CT-InSAR) which enables much wider observable area than an existing nadir-looking radar altimeter.
    This paper aims at reporting the present state of our feasibility study of the COMPIRA satellite system, especially concerning four issues as the very first phase results.
    First is orbit selection, considering compensation for the effects of oceanic tidal constituents which requires non-sun-synchronous orbit and temporal/spatial coverage of observation.
    Second, amount of possible electrical power generation is estimated. CT-InSAR requires much electrical power in spite of the unfavorable and unstable sunlight condition in non-sun-synchronous orbit.
    Third is data transmission analysis. Data amount obtained from SHIOSAI will be enormous due to the measurement principle of CT-InSAR and its much wider observable area. The sea area to be targeted is discussed with the priority of each sea area.
    Fourth, our current major issue: on-orbit deformation of SAR baseline structure induced by thermal strain. Although requirement of micron-order mechanical alignment is indispensable for highly precise altimetric measurement by CT-InSARs, it will be quite difficult to hold thermal strain in range of requirements due to its long baseline. Roll-angle deformation analysis is also needed because thermal distribution may cause out-of-plane bending. In addition, thermal design of non-sun-synchronous satellite is typically more complex than sun-synchronous satellite. Then, we roughly analyzed temperature distribution in some special case of orbit, and estimated thermal strain distribution. Moreover, the way to reduce and/or measure those thermal strain are pointed out as a problem to be studied.

     
    Corresponding author:

      Dr Kobayashi Takashi
      Japan Aerospace Exploration Agency
      2-1-1 Sengen, Tsukuba, Ibaraki
      305-8505 Tsukuba, Ibaraki
      Japan
      E-mail:
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