| 摘要: | 本論文所發展的中央大學太空氣象儀器酬載（Space Weather Instrumental Payload SWIP - Block of Central University, 簡稱BCU）透過莫斯科大學的實驗科學教育微衛星（Experimental Scientific Education Micro-Satellite, ESEMS）的國際學術合作計畫，順利與Tatiana-2衛星完成整合與測試，於2009年9月升空入軌，並且成功蒐集了軌道上的電子溫度與磁場等科學數據。 相較於2004年發射的福爾摩沙衛星二號所搭載的高空大氣閃電影像儀（Imager of Sprites and Upper Atmospheric Lightning, 簡稱 ISUAL）雖同樣是作為電離層太空氣象的研究用途，但是BCU不僅是首顆國內自製的太空氣象酬載，也是首顆完全由大學研究團隊設計、製作與測試的酬載。BCU的主要科學儀器，包括了量測範圍500~4000°K，實測精度50°K的電子溫度探針（Electron Temperature Probe, ETP），以及量測範圍-50000nT~+50000nT、實測精度25nT的磁敏電阻式磁力計（Magneto-Resistive Magnetometer, MRM）。其中ETP是首次運作在高緯度軌道來進行電子溫度資料收集，而MRM則是首次應用於科學研究量測用途。 BCU以智慧型酬載（Smart Payload）的架構為設計目標，致力於整合衛星提供給酬載的資源，特色是與衛星的電子介面僅有單一電源以及RS-422通訊埠，但是內藏的資料處理單元（Data Processing Unit, DPU）及電源轉換模組（Power Converters）使得BCU成為可以同時管理多個儀器進行科學數據收集與紀錄的酬載平台。前述的科學儀器亦是透過DPU在軟、硬體上的無縫整合，能夠協同進行測量任務，並且同步紀錄ETP電子溫度、MRM磁場資料及艙內溫度數據，以利於後續的飛行校正與資料分析。 科學儀器在運送到莫斯科衛星工廠前，都已完成了地面校正程序。在飛行校正的部份，ETP因為獨特的設計，使得它的參考電極電壓同時可做為校正基準；而MRM則是依靠Tatiana-2衛星每分鐘取樣一次的姿態感測磁力計當做校正參考，且MRM經由這個校正步驟，除去了沿著衛星飛行方向約0.146Gauss的衛星環境殘磁。由BCU所收集到科學數據的取樣頻率為2.22Hz（換算空間解析度為3.33km），這些資料經過驗證也顯示出BCU運作正常，並且蒐集到所預期有效的電離層氣象資訊。分析之後更進一步地發現MRM在經過高緯度極光區時，量測到了順磁場電流（Field-Aligned Current, FAC）現象，並且從資料中計算出的朝下及朝上的電流值分別為2μA/m2與3μA/m2，符合一般地磁安定狀態下的觀測值。The Space Weather Instrumental Payload SWIP - Block of Central University, so called the BCU, had been developed and finished the integration tests with the Tatiana-2 satellite by the Experimental Scientific Education Micro-Satellite (ESEMS) project, the international project of academic cooperation with Moscow State University (MSU). The BCU payload had been launched on September 17th, 2009, and collected the scientific data of electron temperature and magnetic field successfully. Comparing with the earlier launched ISUAL (Imager of Sprites and Upper Atmospheric Lightning) payload carried by Formosat-2 in 2004 for similar purpose of ionospheric space weather study, the BCU payload is not only the first Taiwanese scientific payload to be placed aboard a Russian satellite, but also the first scientific satellite payload designed and built entirely by the team from National Central University in Taiwan. There are two main instruments in the BCU: the Electron Temperature Probe (ETP) with a resolution of 50°K from 500°K to 4000°K, and the Magneto-Resistive Magnetometer (MRM) with a resolution of 25nT from -50000nT to +50000nT. This flight brought the ETP its first high latitude observation of electron temperature, and also led the MRM to its first space measuring mission for the purpose of scientific research. The integration of satellite provided resource budget is engaged in design of the BCU for the objective of smart payload architecture. Therefore, the BCU payload platform is capable of parallel managing several instruments to collect and record scientific data with the Data Processing Unit (DPU) and power converters inside, and only interfacing satellite with one pair of power source line and one set of RS-422 communication channel. As a good example, the ETP and the MRM are seamlessly integrated by the DPU both in hardware and software, and well-coordinated to carry out the mission of measuring the electron temperature and magnetic field data synchronously. The temperature inside the BCU chassis is also recorded for convenience of in-flight calibration and data analysis. The pre-flight calibrations had been done before the BCU was shipped to satellite factory in MSU. The electric potential of ETP’s reference electrode could be used as the source of in-flight calibration due to the special structure of ETP. The magnetometer of Tatiana-2 satellite with a sampling period of 1 minute could be used as a reference magnetic field of MRM’s in-flight calibration, and the environmental bias field of 0.146Gauss has been calibrated through this process. The in-flight data acquired by the BCU has a sampling rate of 2.22Hz which is equivalent to a spatial resolution of 3.33km. These data proof that all sensing units and the payload-spacecraft interfaces of the BCU system works well and collects good quality information of space weather as expected. Moreover, the MRM data revealed the existence of field aligned currents in the ionosphere. In the event presented, the current density derived from our magnetic field measurements are about 2μA/m2 and 3μA/m2, respectively, for downward and upward directions, which are comparable to those typically observed at auroral latitudes during quiet geomagnetic condition. |
