| 摘要: | 本論文主要討論PEARL立方衛星的系統設計與軌道模擬，評估任務的可行性，確認各項次系統需求，估算各次系統所需空間、重量、電力與通訊界面，並模擬軌道可能影響衛星任務執行的因素，以實現PEARL立方衛星通訊實驗以及電離層觀測任務。PEARL為一枚低軌通訊實驗立方衛星，預計飛行在500~600公里高的太陽同步圓形軌道，任務壽命1年，其上搭載兩項科學酬載，分別是Ku/Ka波段通訊酬載（Ku/Ka-band Communication Payload, KCP），提供高流量雙向通訊測試網路；小型電離層探測儀（Compact Ionospheric Probe, CIP），可監控全球通訊品質與導航安全。PEARL軌道週期約95分鐘，單一週期日側時間約62分鐘，每日經過同一地點附近兩次，視通訊仰角大小決定通訊時間長短，這些因素關係到衛星的發電量以及可傳輸資料量，且衛星網路實驗同時須跟兩座以上地面站通訊才可執行，所以還需要計算通訊涵蓋面積，以確認地面站之間距離不會太遠。PEARL的基本次系統與結構採用EnduroSat所提供之產品6U立方衛星平台，在本身的軟硬體限制下，估算剩餘可提供給KCP的空間、重量，以及可用電力，並模擬PEARL軌道與姿態對於發電量、通訊時間、通訊涵蓋面積的影響，提供KCP一個實驗平台。由於KCP尚在研發中，因此先以通用的立方衛星平台提供通訊酬載的設計介面需求與限制。模擬結果顯示，PEARL立方衛星可供應臺灣地區的通聯時間為日夜各一次，每次3~8分鐘。供應通訊酬載的最大功率為120 W，若設定SOC低於80%時會進入安全模式，則建議使用時間不超過8分鐘，或降低功率至80 W，才可保持例行運作。若以國立中央大學為通訊涵蓋區域中心，KCP的半波束寬為在5度以上，可涵蓋桃園地區；8~9度以上，可涵蓋北北基桃地區；10度以上，可涵蓋整個北部地區。;The purpose of this thesis is to calculate the available space, mass, power etc., for the communication payload of PEARL under the limitation of the hardware and software. Furthermore, it simulates the orbit and attitude of PEARL. Before the CubeSat is launched and deployed, we need to evaluate the feasibility for the mission. It is important to calculate the volume, mass and the use of the power for each subsystem because the space and weight of CubeSat are limited. PEARL is a LEO and Sun-synchronous orbit CubeSat. The subsystems of PEARL almost adopt the products of EnduroSat. The main mission is the communication experiment. PEARL needs to download the data from science payload CIP and to provide a high throughput downlink/uplink satellite communication network. Its orbit period is about 95 minutes and the sunlight time for an orbit is about 62 minutes. It passes near the same ground station twice a day, and the communication time is related to the elevation angle. These factors affect the solar power generation and the amount of data transmission. In addition, the satellite Internet experiment needs to communicate with two or more ground stations, so we have to consider the footprint area. Because KCP is still under development, it will first provide the interface requirements and the limitations of communication payloads with a general CubeSat platform. The simulation shows that PEARL can provide the communication time for Taiwan once in day and once in night, and each time is 3 to 8 minutes. The maximum power that system can provide to the communication payload is 120 W. If PEARL enters the safety mode when the SOC is under 80%, it suggests to use KCP for less than 8 minutes or reduce the power to 80 W. It can maintain the routine operation. If NCU is the center of the communication footprint area, the cone half angle of KCP needs to be above 5 degrees, which can cover Taoyuan. If it is more than 8~9 degrees, it can cover New Taipei, Taipei, Keelung and Taoyuan. If it is more than 10 degrees, it can cover the Taiwan northern region. |
