Mon, May 17, 2021 page9

• Chinese rocket’s chaotic fall to Earth highlights problem of space junk 中國火箭驚險墜落　凸顯太空垃圾問題

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  Remnants of China’s biggest rocket landed in the Indian Ocean on May 9, ending days of speculation over where the debris would hit and drawing US criticism over a lack of transparency.

  But the fiery fate of a booster rocket, wherever it comes down, speaks to the larger issue of space debris and space sustainability, especially as space becomes a target not just for national space programs but also increasingly the private sector. Under international treaty, private space actors, who are expected to put 45,000 satellites in low Earth orbit over the next several years, are under the legal responsibility of their host nations.

  Add to that an estimated 9,300 tonnes of space junk that is already orbiting the planet and the probability of space collisions and debris pollution is an issue of concern.

  

  A computer-generated image of objects in Earth orbit that are currently being tracked. Approximately 95 percent of the objects in this illustration are orbital debris, ie, not functional satellites. The dots represent the current location of each item. 此電腦生成影像標示出地球軌道上被追蹤之物體，每個點代表每件物體之目前位置，這些物體約百分之九十五為環繞地球軌道之殘骸，例如報廢的人造衛星。

  Photo: NASA via Wikimedia Commons 照片：美國太空總署∕維基共享資源

  Previously, a piece of paint the size of a fingernail struck the windscreen of a space shuttle, piercing two of three layers of glass.

  The fate of Long March 5B could refocus governments and international bodies on the issue of space sustainability, and that could provide more opportunity to firms like UK-based Astroscale that are preparing to tackle the debris problem with commercial junk-collecting services.

  Astroscale is currently demonstrating a vehicle called “ELSA-d” in lower Earth orbit to show that space debris clean-up is indeed possible. It is a fiendishly difficult task, especially if the target satellite is spinning and tumbling. The test is using a satellite to capture a test drone with a magnet. In time, larger objects will require a robotic arm.

  

  A handout photo made available by the European Space Agency (ESA) shows an illustration of the first active debris removal mission ClearSpace-1, which in 2025 will capture and take down for re-entry the upper part of a Vespa (Vega Secondary Payload Adapter) used with Europe’s Vega launcher. 左圖：歐洲太空總署提供之新聞照，圖示將於二○二五年開始之主動清除太空垃圾任務ClearSpace-1，抓取原置於歐洲織女星運載火箭頂端之「織女星二級有效載荷適配器」，將其移出地球軌道，讓它重返大氣層。

  Photo: AFP 照片：法新社

  (The Guardian)

  中國最大火箭之殘骸已在五月九日墜落印度洋，讓數天來對殘骸究竟將撞擊何處的猜測告一段落，也引起美國對此事缺乏透明度的批評。

  火箭推進器在熊熊烈焰中的宿命，無論它掉在哪裡，都觸及太空垃圾與太空永續性這更大的問題，尤其此時太空不僅成為國家太空計畫之標的，也愈趨成為私有公司之標的。在未來幾年中，經營太空業務的私有公司將把四萬五千顆衛星送入低空地球軌道，而根據國際條約規定，法律責任是由其東道國所承擔。

  此外，據估計，現已有九千三百噸太空垃圾在繞著地球轉，太空中的碰撞與垃圾污染問題令人關注。

  此前，一塊指甲大小的油漆打到一艘太空船的擋風玻璃，刺穿了三層厚玻璃的其中兩層。

  長征五號的命運可能使政府及國際組織重新關注太空的永續性問題，而可能給像英國的Astroscale這樣的公司帶來更多機會，這些公司正準備提供收集垃圾之商業化服務，以解決太空垃圾問題。

  Astroscale正在地球較低軌道展示一種名為「ELSA-d」的運載工具，以證明清除太空垃圾的確可行。這是一項艱鉅的任務，尤其是目標衛星處於旋轉與翻滾的情況時。該測試透過衛星進行，以磁鐵來捕獲測試用無人機，最後也會需要用到機械臂來抓取較大的物體。

  (台北時報林俐凱編譯)
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