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2020 marks the 20th anniversary of the International Space Station (ISS) since the first group of astronauts arrived at the ISS on Nov 2, 2000.
2020年是國際空間站運(yùn)行20周年。2000年11月2日，第一批宇航員抵達(dá)國際空間站。

As a milestone of space exploration, the ISS didn’t come cheap. It cost about 989 billion yuan, took decades to build and is by far the world’s largest space project.
作為太空探索的一塊里程碑，國際空間站造價不菲。其耗資約9890億元，歷時數(shù)十年建成，是目前全球最大的太空項目。

When it comes to achievements, ISS has accommodated at least 3,000 research projects, from research on Alzheimer’s to toothpaste.
在成就方面，國際空間站已為至少3000個研究項目提供平臺，研究類別從阿茲海默癥到牙膏。

But still, with a 26-billion-yuan bill annually, ISS can’t make ends meet. NASA has been promoting to commercialize ISS. In 2019, NASA announced that the ISS would open for business to private citizens. According to Reuters, NASA will allow up to two private trips to the station per year, each lasting up to 30 days. NASA estimated the cost of a flight would be around $50 million (about 330 million yuan) per seat.
但每年260億元的花銷仍令國際空間站入不敷出。美國航空航天局一直在推動國際空間站商業(yè)化。2019年，美國航空航天局宣布國際空間站將向個人開放。據(jù)路透社消息，美國航空航天局每年將允許最多兩次私人的國際空間站旅行，每次旅行長達(dá)30天。美國航空航天局預(yù)計每次太空之旅的人均花費為5000萬美元左右（約合3.3億元人民幣）。

However, ISS isn’t in the same state as it was in its youth. After 20 years of circling the Earth, ISS has suffered multiple problems. For example, there have been several air leak issues, the most recent of which was announced by NASA on Sept 29. Meanwhile, without enough propellant, ISS will not stay in orbit and could fall, leading to disaster.
然而，國際空間站卻不復(fù)當(dāng)年的狀態(tài)。繞地球運(yùn)行20年后，國際空間站存在諸多問題。比如，國際空間站已發(fā)生幾次氣體泄漏問題，最近的一次由美國航空航天局于去年9月29日發(fā)布。此外，如果沒有充足的推進(jìn)劑，國際空間站便停留在軌道上，或許會發(fā)生墜落，引發(fā)災(zāi)難。

“Worst, worst case, I guess it’s a 9/11, right?” Jonathan McDowell, an astronomer at Harvard told Space.com. “Because it’s at worst case a plane crashing, part of which is in a populated area.”
“最壞、最壞的情況，我猜是像911那樣的，對吧？”哈佛大學(xué)天文學(xué)家喬納森·麥克道爾向太空網(wǎng)表示?！耙驗闆]有比飛機(jī)墜毀、其中一部分還落在人口密集區(qū)更糟糕的了。”

So how can the space station make a safe re-entry? Despite certain risks, NASA is considering a scheduled de-orbit – maneuvering the station to a special angle in its orbit, making the re-entry more predictable and allowing managers to target the debris to the vast, sparsely populated southern Pacific Ocean.
所以，國際空間站能夠如何安全重新進(jìn)入大氣層呢？盡管存在一定風(fēng)險，美國航空航天局正在考慮脫離軌道的計劃 —— 將空間站移至軌道中的特定角度，使其返回過程更可預(yù)測，以便管理人員將殘骸投放至廣闊無人的南太平洋。

An alternative is to launch new station modules to replace the old ones. “Each module is going to be designed with its own guidance, navigation and control, its own thruster capabilities,” said Christian Maender, director of in-space manufacturing and research for Houston-based company Axiom. “So when they need to, they can separate and return through Earth’s atmosphere on their own.”
另一種方法是發(fā)射新的模塊艙來取代舊的?！懊總€模塊艙都將配有自身制導(dǎo)、導(dǎo)航和控制系統(tǒng)，并具備自主推進(jìn)性能，”總部位于休斯頓的Axiom公司的太空制造和研究主管克里斯蒂安·馬恩德說道。“所以在有需要的時候，它們可以自行分離，自主穿過大氣層返回地球。”

For now, ISS will continue through at least 2024.
目前，國際空間站運(yùn)行延至2024年。

(Translator & Editor: Wang Yue (Intern) AND Wang Xingwei)
http://www.cycjq.cn/story/3647.html