Search

A deployable truss called as TETRUS (Tetra Trigonalprism Truss) to be applied to a large multi-beam antenna with an aperture diameter of 30 m is under research and development setting a goal to mount the antenna on a geostationary platform communication satellite. A model of TETRUS with basic structure of trigonal prism was experimentally fabricated for thermal tests, and the effect of thermal environment on its mirror surface was evaluated. Described is an outline of the structure of TETRUS of which basic module is combination of three equilateral trigonal prisms and the mechanism of deployment operation. A small model with an aperture diameter of 1.7 m was used for thermal environment tests. Gold plated molybdenum mesh was used for reflective mirror surface. Thermal deformation volume was estimated by numerical analysis for a model of truss section. The results of analyses on the deterioration of mirror surface accuracy caused by gravitational deformation and thermal deformation indicate that the volume of deformation is minute and includable in measurement error. The thermal environment model suspended by suspension-type test equipment constructed using cable wires was placed in a thermostatic chamber. The result of the test shows that the influence by thermal environment is stronger at low temperature region (-35 C) than high temperature region (+75 C)., 静止プラットフォーム型衛星に搭載する目的で、開口径30mの大型マルチビームアンテナに適用する展開トラスTETRUS(Tetra Trigonalprism Truss)の開発を進めている。3角柱を基本構造とした展開トラスTETRUSの熱試験用モデルを試作し、熱環境で鏡面に与える影響を評価した。正3角柱を3つ組合わせて基本モジュールとするTETRUSの構成と展開動作の機構を記述した。熱環境試験には開口径1.7mの小型モデルを用いた。反射鏡面には金メッキモリブデンメッシュを用いた。トラス部分のモデルに対して熱変形量を数値解析により推定した。重力変形および熱変形による鏡面精度の劣化を解析した結果、変形量は微小で測定誤差に含まれることが分かった。ケーブルワイヤを用いて構成した宙吊り型試験機を用いて熱環境モデルを恒温槽内に配置した。試験の結果、低温側(-35度C)の方が高温側(+75度C)よりも熱の影響は強く出ることが分かった。