縮裝型小衛星氧原子酬載：實作、功能與環境驗證;Compact Atomic Oxygen Payload for Small Satellites: Implementation, Functional and Environmental Verification

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Title:	縮裝型小衛星氧原子酬載：實作、功能與環境驗證;Compact Atomic Oxygen Payload for Small Satellites: Implementation, Functional and Environmental Verification
Authors:	高凱爾;Gacal, Glenn Franco B.
Contributors:	太空科學與工程研究所
Keywords:	有效載荷;atomic oxygen;payload;space engineering
Date:	2022-06-21
Issue Date:	2022-07-13 18:12:02 (UTC+8)
Publisher:	國立中央大學
Abstract:	隨著廉價低軌道人造衛星開始大量使用，人類對於熱氣層高層大氣科學的需求也隨之增加。這因此也產生了機會讓大學機構建造一系列提供電離層及熱氣層參數原地測量的小型衛星觀測網。氧原子在高層大氣扮演極重要的角色。氧原子的含量會影響高層大氣對低軌衛星所產生的軌道擾動及限制衛星壽命空氣阻力，尤其是在太陽極大期的狀況下。在高層大氣的數值模擬中，氧原子會透過大氣標高及O/N2濃度比例影響電離層及熱氣層的變化。前者會影響高層大氣的厚度，後者會因為原子離子的壽命比分子離子長而影響電離層電漿濃度。氧元子另外也是非常有效率的氧化劑，因而會對低軌衛星的表面產生腐蝕作用。低地球軌道的氧元子分佈因此對高層大氣科學及衛星的飛行環境都很重要。本研究的目的為設計並實現、驗證一個適合由小型衛星攜帶的氧元子感測器酬載。光量計（actinometer）是一種操作簡單，可以用來量化氧元子通量及累積通量的儀器。本研究以銀製的薄膜電阻加上二線電阻量測電路來實現一個氧元子感測劑原型。本酬載的耗電量只有 0.16 W，佔的空間只有 0.1U，外加擺在衛星外部曝曬在氧原子環境下的感測計。地面上用氚燈進行的功能測試已驗證溫度變化對反演出來的氧原子通量所產生的影響。在薄膜電阻的電阻值不變的狀況下，隨著時間增加（減少）的溫度會導致反演出的通量產生正（負）的變化。氚燈測試因為溫度變化的影響遠大於薄膜電阻被氧原子腐蝕的影響，因而無法用來驗證薄膜電阻腐蝕的運作機制。反之，我們使用硫來啟發薄膜電阻的腐蝕作用，驗證後端電路能夠透過電阻值的變化偵測到環境對薄膜電阻的腐蝕作用。總之，我們實現並驗證了一個適合小型衛星使用的氧原子感測器酬載原型。本酬載使用的1.1 μm厚度的銀薄膜電阻能夠以 1 Hz 的採樣頻率偵測太陽極大及極小期的氧原子通量。本酬載將於中大未來的 IDEASSat Lite 衛星任務上進行實飛測試，也可成為未來其他小型衛星及探空火箭任務的輕量型酬載。;The gradual emergence of economical low Earth orbit microsatellites has fueled the interest of atmospheric and ionospheric science in the thermosphere. This paves the possibility to create a network of in situ ionospheric and thermospheric data collection that is definitively supported and utilized at a university level. Specific to this region of the atmosphere, Atomic Oxygen has been playing a prominent role in numerous mechanisms and processes in the ionosphere. It has been shown that Atomic Oxygen has a strong contribution to disrupting satellite trajectories/lifetime due to its effects on neutral atmospheric thickness and satellite drag especially during solar maximum years. In physics-based and numerical models, the impact of Atomic Oxygen is represented by utilizing the scale height parameter and the O/N2 density ratio parameter. The former affects the thickness of the upper atmosphere, while the latter can affect the lifetime of ionospheric plasma prior to recombination, due to the longer lifetime of atomic versus molecular ions. While conducting in situ observation further advances the scientific understanding of such ionospheric processes, Atomic Oxygen is also corrosive to most current spacecraft materials, thereby presenting unwanted risk in fulfilling space mission objectives. Therefore, not only is characterizing the atomic oxygen environment advantageous in the scientific understanding of the Earth’s upper atmosphere, but it will also shed light on how spacecraft in Low Earth Orbit (LEO) behave and can survive in such an environment. The aim of the study is to create an Atomic Oxygen payload that is well-suited to the mission requirements and design constraints present in a micro- or nanosatellite setting. A simple yet proven method of quantifying Atomic Oxygen parameters (i.e. flux and fluence) is by use of an actinometer. The chosen actinometer design for the study is a silver-based film sensor in a two-wire configuration for Atomic Oxygen flux and fluence determination. The payload suite only consumes 0.16W of power and only occupies 0.1U space with half of the payload placed outside of the spacecraft for Atomic Oxygen exposure. Ground functional tests with a deuterium lamp setup has provided significant results as to how temperature variation heavily relates with the computed Atomic Oxygen flux. Positive (negative) flux values are garnered with increasing (decreasing) temperature change accompanied with no change in film resistance. However, the deuterium lamp test could not reproduce this silver film erosion due to the parasitic heat by the lamp that overwhelms the film erosion detection. On the other hand, sulfur containing gas experiments has shown that silver corrosion is verifiably detectable by the payload suite. In conclusion, an atomic oxygen payload suitable for small satellites has been developed and is verified on the ground. Using a 1.1 μm thick silver film sensing material at a sampling frequency of 1 Hz, the payload is designed to detect atomic oxygen flux during solar minimum years and solar maximum years. The NCU-made payload is scheduled to exhibit its technology demonstration aboard the IDEASSat Lite project. It is hoped that the payload suite can be utilized amongst numerous CubeSat and sounding rocket missions and improved upon based on technical needs and mission objectives.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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