充滿台灣味的衛星

福衛五號展現台灣太空研發能量
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2018 / 4月

文‧曾蘭淑 圖‧國家太空中心


歷經6年研發,總經費新台幣56.59億元的福爾摩沙衛星五號,是台灣第一枚自主研發製造的高解析度光學遙測衛星。

2017825日福衛五號在美國加州范登堡空軍基地順利發射升空後,卻傳出衛星休眠、影像失焦等問題,在研發團隊不眠不休地解決困難下,4個月後,福衛五號從太空傳來清晰的台灣空照圖,向世界展現台灣太空科技實力。


2017825日凌晨251分,福爾摩沙衛星五號(以下簡稱福衛五號),搭乘美國SpaceX公司的「獵鷹九號」火箭,順利發射到720公里外太空,順著太陽軌道運行,執行遙測影像等任務。

福衛五號,發射!

發射後的1119秒,福衛五號順利與火箭分離。83分鐘後,挪威北極地面接收站首度接收到福衛五號訊號;100分鐘後,挪威第二次收到訊號。因為衛星軌道傾角所涵蓋地球南北緯度的範圍有限,直至400分鐘後,台灣地面接收站才首度接收到福衛五號訊號。

「我在美國的發射站,從電話那一頭,聽到台灣接收站歡聲雷動的聲音」,6年來從頭到尾擔任福衛五號計劃主持人的張和本博士停了3秒,說:「那一刻,我內心真是充滿了感動。」

第一顆自主研發製造的衛星

台灣1994年決定開始發展衛星,由於沒有基礎,福衛一號至三號都是以國際合作的方式,委託美、英、法等國代為設計、製作衛星的元件與次級系統,再組裝成衛星。換句話說,是以「發包」的方式找歐美公司代工。

唯獨福衛五號由台灣國家太空中心以福衛二號為藍本,從頭設定規格與需求,再結合產、學五十多個團隊進行研發與製作。

福衛五號寫下很多個第一的紀錄。衛星本體部分,有第一個台灣人製作的衛星電腦,第一個自行編寫的衛星飛行軟體和第一個自行配置的電力控制與配置單元。福衛五號二項主要的酬載(放在衛星上的科學儀器),一是光學遙測酬載儀器(RSI),其中CMOS光學感測器是台灣自製的,這其中結合了許多電機、機械、結構、光學等領域的關鍵元件。另一項酬載「先進電離層探測儀」,也是中央大學太空科學研究所累積20年經驗,所研製可以量測電離層電漿參數的科學儀器,能夠預測地震前可能的異常現象。

從無到有,累積能量

台灣自主研發衛星的路程,從計劃主持人張和本身上,可以看出從無到有的軌跡。

張和本說,福衛五號是一棒接一棒經驗累積下來的成果。1994年台灣委託製作間碟衛星翹楚的美國TRW公司,製作福衛一號,需要有本國專家參與,當時還是國家太空計劃籌備處主任戎凱四處挖角,拜託在美國馬歇爾太空飛行中心工作的張和本回來參與。

TRW公司的合約中,技術移轉的部份,包括送廿多位台灣工程師到美國TRW受訓2年半,就由張和本帶頭當領隊。

「話說是技術轉移,但仍有人家不願讓你知道的技術,例如部份元件會在別的廠房製作,我鼓勵工程師盡量挖,很多know-how靠著向對方發問,自己揣摩領悟。」張和本要求每人每月都要寫一本技術報告,當初參與福衛一號訓練的工程師與專家,其中有10位成為現在太空中心研製福衛五號的基本班底,廿多本技術報告則成為解決問題重要的「參考書。」

自主研發,勇敢走出來

福衛一號到三號,唯獨沒有四號,原來張和本回國前一年,正是國家太空中心士氣最低迷之時。由於「ARGO」衛星採購計劃的得標廠商出現問題,最後國家太空中心不得不與廠商解約,導致衛星發展計劃停滯,甚至出現是否裁撤太空中心的聲音。不想受制外國廠商,「自主研發」成為國家太空中心不得不走的路。

還有許多太空科技的元件,例如黑白解析度達30公分的鏡頭屬於軍事等級,是管制輸出的項目,就是有錢想買也買不到。台灣想突破,不想跟在人家後面,唯有自主研發。

為了撰寫福衛五號計劃,於是已在美國波音公司上班12年的張和本再度被挖角,但回台灣的薪水不到波音的一半。談到2009年初回來時的考量,張和本現在回想起來仍說:「真是不容易,因為剛好遇到2008年美國因為信貸危機爆發全球經濟不景氣,原本想應該繼續留在波音公司,才能有更好的退休生活。」

但是,年邁雙親的呼喚戰勝了對金錢的掙扎,「畢竟台灣是我的『家』,我的爸爸媽媽今年92歲了,住在台北,因為在台灣,我經常都可以去看他們。」張和本笑著說。

眾志成城,解決困難

自主研發說得容易,6年走來,研發團隊所遇到的難題與挑戰不計其數。張和本舉例說,如何將直徑45公分、重達10公斤的鏡片,裝在遙測酬載的結構體上,涉及光學與機械的結合。書本有說可以用「鎖的」或是用「黏」的,但沒有說怎麼鎖、怎麼黏?又要克服在外太空環境下,黏上去的鏡片不會退化、變形的問題!太空中心十多人組成的團隊,花了半年時間,終於克服這個問題。

又像對光學遙測酬載儀器進行壽命測試,每次經由外太空環境的測試,纏繞的金線都翹起來,經過多次失敗與實驗,終於找出使用比純度99.99還要再純的金線,才能「真金不怕火煉」地通過試煉。

張和本說:「團隊就是一個一個解決問題,我們找出來的解決辦法,可能不是最好,但是發現我們遇到任何問題,都可以一一解決,就像三個臭皮匠勝過一個諸葛亮這句話。」台灣太空科技的研發能量就這樣一一累積起來。

考驗不斷

其實,發射成功的喜悅並沒有持續多久,工作團隊發現,福衛五號繞第二圈後傳來的數據「怪怪的」、「好像出了問題。」

張和本稱福衛五號為「我們的衛星」,他說:「我們的衛星會自己調整角度朝向面對太陽的方位來發電」,但升空100分鐘後卻發現福衛五號電力一直掉,甚至啟動自我保護的休眠模式。

國家太空中心團隊原本歡欣鼓舞的心情也跟著掉至谷底,副主任余憲政知道後眼淚更是掉了下來。因為一旦福衛五號無法感測到太陽自行發電,就「任務結束」,也就「一切都結束了。」

由於福衛五號每99分鐘繞行地球一周,操控團隊索性不回家,留在太空中心,不眠不休地跟著福衛五號,每99分鐘一次,解讀衛星傳回來的資訊,試著找出問題所在。團隊苦中作樂說,「那時候衛星一直睡覺,我們都沒睡覺。」

3天後我從美國回台灣,他們就告訴我找出問題了。」張和本如今可以侃侃而談,「原來衛星的4個反應輪,其中有2組的電線錯置,導致我們的衛星回到最後的保護模式(phoenix mode),是我們參照福衛三號的設計改良,讓衛星遇到問題時自行啟動保護模式。」

張和本說,「我覺得我們的團隊很厲害,因為衛星的飛行軟體每一行程式都是我們自己寫的,因此軟體工程師靠著修正程式,把兩組正確的電線接回去。4個輪子,就是4次階乘(4=4×3×2×124),有24種不同組合方式,工程師發現問題後,從地面模擬24種情形,根據原來的電線連接圖,想辦法從地面『修理』它。」

解決後,操控團隊告訴張和本:「經過這次的考驗,以後再怎麼難的問題都不怕了。」

美國第一個繞行地球的太空人約翰.格倫曾說:「真正的英雄是面對困難障礙,在放棄之前,再嘗試最後一次的人。」福衛五號上太空,證明台灣太空科技實力經得起考驗。

守護台灣,科技外交

沒有想到,福衛五號201797日傳回的首批影像又出現光斑與模糊問題。太空中心的專家學者不斷測試,採用溫度調控及地面回溯修正等方式調校,去年11月照片解析度已提升至黑白3米、彩色5米的水準。

福衛五號發射半年來累積拍攝了2,300組影像,以及成功執行全球電離層觀測,可以提供給國際救援組織與各國政府在防災勘災、國土安全、環境監控上使用,成為科技外交的「大使」。

今(2018)年26日晚間發生的花蓮地震,福衛五號已經發揮功能,提供災前災後的山坡地大面積照片比對,哪邊可能發生崩塌,哪些地方產生變異的重要勘災資訊,是守護台灣的重要幫手。

新的里程碑

福衛五號自主研發的成功,讓台灣站上另一個關鍵的立基點。同時福衛七號已完成測試,計劃今年68月發射上太空,替為期10年的第二期太空計劃畫上句點。

今年2月甫上任的國家太空中心主任林俊良指出:「我的任務就是規劃從2019年開始第三期的國家太空科技發展計劃。」

林俊良胸有成竹地說:「下一個10年,台灣將研發更具前瞻性衛星的技術,並且進行跨出地球、繞行月球或是火星的探索;更重要的是,全世界都是朝向衛星商業化發展的趨勢在走,未來也希望台灣能將卅年所累積自主研發的技術擴展到產業界,帶動民間產業的發展,甚至進一步形成太空產業鏈,布建太空產業園區。」

太空科技對一個國家來說,是以和平方式展現的國家實力。林俊良語重心長地說:「台灣雖然是小國,與其他大國投入太空科技的人力與經費是天壤之別,但台灣在世界半導體的領先能量與太空產業的研發能力,可以特別聚焦在關鍵的『組件』、『模組』與『系統』製造上,形成具有台灣特色的太空產業,讓其他國家可以向台灣購買。」

太空夢過去只專屬於美蘇等大國,福衛五號成功地證明台灣現在也有這個能力,太空夢不再遙不可及。

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近期文章

英文

A Taiwanese Satellite

Esther Tseng /photos courtesy of NSOP /tr. by Scott Williams

Formosat-5, Taiwan’s first domestically developed and produced high-resolution optical telemetry satellite, took six years and NT$5.66 billion to create.

Launched from Vandenberg Air Force Base in the United States on August 25, 2017, the satellite experienced early problems with its remote sensing instrument that prevented it from producing the high-­resolution images its designers expected. The development team immediately went back to work, and spent four nerve-racking months identifying the cause of the problem and crafting a solution. Their hard work paid off, enabling the satellite to produce clear and sharp aerial maps of Taiwan, and showing the world the strength of Taiwan’s indigenous space technology.


 

Formosat-5 shot into space on the back of a SpaceX Falcon-9 rocket at 2:51 a.m. Taiwan time on August 25, 2017. Successfully inserted into a sun-synchronous orbit 720 kilometers above the Earth’s surface, the satellite then began its remote-sensing mission.

Three, two, one, lift off!

Formosat-5 separated from the rocket 11 minutes and 19 seconds after launch. The satellite’s first contact was with Norway’s Svalbard Satellite Station, 83 minutes from launch. Its second contact, also with a Norwegian ground station, came at 100 minutes. But Formosat-5’s orbital inclination meant that it was 400 minutes after launch time when Taiwan received its first signals from the satellite.

“I was at the launch facility in the US, and heard the cheers from the Taiwan receiving station over the phone,” says ­Chang Ho-pen, who has been the Formosat-5 project director since the program’s inception. He pauses a few seconds, then adds: “In that moment, I was filled with emotion.”

Developed and produced in Taiwan

Taiwan made the decision to begin developing satellites in 1994. Without a background in the field, we sought out international partners for Formosat-1 through Formosat-3. We worked with the US, the UK and France to design and manufacture the components and secondary systems, then assemble the satellites. Basic­ally, Taiwan solicited bids and then contracted out the work to companies in the US and Europe.

The process changed with the Formosat-5 project, which Taiwan’s National Space Organization managed from start to finish. The NSPO based Formosat-5 on Formosat-2, drawing up the project’s specifications and parameters, then pulling together more than 50 teams from industry and academia to handle development and production.

Formosat-5 achieved a number of firsts for Taiwan. The satellite itself includes Taiwan’s first self-produced onboard satellite computer, onboard flight software, and power control and distribution unit (PCDU). The satellite also carries two primary payloads. The first is a remote sensing instrument with a CMOS image sensor that was manufactured in Taiwan utilizing components that integrate technologies from a variety of fields, including optics, electronics and mechanical engineering. The second is an advanced ionospheric probe. Developed and produced by the Graduate Institute of Space Science at National Central University drawing on its 20 years of experience in the field, the probe is designed to measure iono­spheric plasma and may detect anomalies occurring prior to earthquakes.

Our own R&D

Chang Ho-pen returned to Taiwan in 2009. NSPO morale had reached a nadir in the previous year, when problems with a contractor forced the organization to terminate its ARGO satellite project. The decision brought Taiwan’s satellite development program to a halt and led to questions about whether the NSPO itself should be scrapped. Unable to depend on foreign contractors, the NSPO had little choice but to pursue its own research and development.

Further supporting that decision was the fact that many space-related technologies, such as 30-centimeter-resolution black-and-white optics, are military grade and therefore export-controlled items that are unavailable for purchase. If Taiwan wanted to acquire better technology, it would have to develop it itself.

Challenge upon challenge

While the NSPO was thrilled with the successful launch of Formosat-5, their joy didn’t last. The data the satellite sent after its second orbit indicated that the satellite was experiencing difficulties.

Chang is in the habit of calling Formosat-5 “our satellite.” He explains: “Our satellite adjusts its angle to the sun to generate electricity.” But just 100 minutes after its launch, the NSPO team discovered that its power levels were dropping so rapidly that the satellite had switched into its dormant mode.

When the team heard the news, their mood plummeted. NSPO deputy director-general Yu ­Shiann-jeng even wept, because if Formosat-5 couldn’t detect the sun to generate its own power, the mission and the whole program were done.

“When I returned to Taiwan from the US three days later, they told me they had found the problem. It turned out that two of the satellite’s four reaction wheels had wiring issues, which caused our satellite to return to its ‘phoenix’ mode. This is a protective mode that the satellite puts itself into when it encounters a problem. We borrowed it from Formosat-3’s design.”

Chang says, “Our team is amazing. Since we had written every line of the flight software ourselves, our software engineers were able to look at the original wiring diagram, find the cause of the problem, and resolve the problem from the ground by rewriting the program to correctly control the two miswired reaction wheels.”

Having solved the issue, the control team told him that the experience had left them feeling as if they could take on any problem, no matter how difficult.

John Glenn, the first American astro­naut to orbit the Earth, once said that real heroes are people who, when faced with a difficult obstacle, try one more time before giving up. Formosat-5 demonstrated that Taiwan’s space technology is up to the test.

Technological diplomacy

But the Formosat-5 team had still another challenge ahead of them. When the satellite sent back its first images on September 7, 2017, they were blurry and dappled with light spots. NSPO experts ran test after test, and in November 2017 succeeded in improving the satellite’s resolution to three meters for black-and-white images and five meters for color images through a combination of temperature adjustments and a technique called deconvolution.

Over the last six months, the satellite has captured 2,300 sets of images and taken iono­spheric measurements that can be offered to governments and international aid organizations, functioning as a sort of “technological ambassador” that assists with disaster prevention, national security, and environmental monitoring.

The satellite showed what it is capable of after an earthquake struck Hua­lien on February 6, 2018. By comparing its pre- and post-quake photos of mountain areas, the relief effort was able to identify changes to the terrain and the locations of possible landslides. Such data is invaluable to researchers and can help protect Taiwan in the event of future disasters.

A new milestone

The successful development of Taiwan’s Formosat-5 has gained us a crucial foothold in space technology, and now the NSPO has completed its testing of Formosat-7, a collaboration with the US’s National Oceanic and Atmo­spheric Administration (NOAA) that will collect weather data. Formosat-7 is scheduled to launch between June and August 2018 and will bring the second ten-year phase of Taiwan’s space program to a close.

Lin Chun-­liang, who became director-­general of the NSPO in February 2018, says: “My mission is to plan out the third phase of the national space technology development program, which will begin in 2019.”

He explains: “Over the next ten years, Taiwan will develop still more forward-looking satellite technologies. We will also move beyond the Earth with orbital explorations of the Moon or Mars. With the global trend towards commercialization of satellite development, we hope to extend Taiwan’s 30 years of accumulated R&D into the commercial sphere to drive private-sector development, the formation of a space industry production chain, and the establishment of a space technology industrial park.”

Space technology represents a peaceful means of developing a country’s national power. Lin speaks from the heart when he says, “Taiwan may be small and can’t throw nearly the manpower or money that larger countries can into space technology. But we can create a space industry appropriate to Taiwan by focusing our space technology R&D skills and world-leading semiconductor capabilities on the production of key assemblies and allowing other countries to buy them from us.”

Access to space used to be limited to the likes of the US and the Soviet Union, but now the success of Formosat-5 has shown that Taiwan too has the capability to reach for the stars.

 

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