Using a radar instrument on an orbiting spacecraft, scientists have spotted what they said on July 25 appears to be a sizable salt-laden lake under ice on the southern polar plain of Mars, a body of water they called a possible habitat for microbial life. The reservoir they detected — roughly 20km in diameter, shaped like a rounded triangle and located about 1.5km beneath the ice surface — represents the first stable body of liquid water ever found on Mars.
Whether anywhere other than Earth has harbored life is one of the supreme questions in science, and the new findings offer tantalizing evidence, though no proof. Water is considered a fundamental ingredient for life. The researchers said it could take years to verify whether something is actually living in this body of water that resembles a subglacial lake on Earth, perhaps with a future mission drilling through the ice to sample the water below.
“This is the place on Mars where you have something that most resembles a habitat, a place where life could subsist,” said planetary scientist Roberto Orosei of Istituto Nazionale di Astrofisica in Italy, who led the research published in the journal Science. “This kind of environment is not exactly your ideal vacation, or a place where fish would swim,” Orosei added. “But there are terrestrial organisms that can survive and thrive, in fact, in similar environments. There are microorganisms on Earth that are capable of surviving even in ice.”
Photo: AFP
照片：法新社
The detection was made using data collected between May 2012 and December 2015 by an instrument aboard the European Space Agency’s Mars Express spacecraft that transmits radar pulses, which penetrate the Martian surface and ice caps. “This took us long years of data analysis and struggles to find a good method to be sure that what we were observing was unambiguously liquid water,” said study co-author Enrico Flamini, chief scientist at the Italian Space Agency during the research. The location’s radar profile resembled that of subglacial lakes found beneath Earth’s Antarctic and Greenland ice sheets.
Mars long ago was warmer and wetter, possessing significant bodies of water, as evidenced by dry lake beds and river valleys on its surface. There had been some signs of liquid water currently on Mars, including disputed evidence of water activity on Martian slopes, but not stable bodies of water. Orosei said the water in the Martian lake was below the normal freezing point but remained liquid thanks in large part to high levels of salts. Orosei estimated the water temperature at somewhere between minus 10°C and minus 70°C.
It remains to be seen if more subsurface reservoirs of water will be found or whether the newly discovered one is some sort of quirk, Orosei said. If others are detected and a network of subglacial lakes exists like on Earth, he said, that could indicate liquid water has persisted for millions of years or even dating back to 3 to 0.5 billion years ago when Mars was a more hospitable planet.
The question would be, Orosei added, whether any life forms that could have evolved long ago on Mars have found a way to survive until now. “Nobody dares to propose that there could be any more complex life form,” Orosei said.
(Reuters)
科學家在七月二十五日表示，藉助於一艘繞軌道運行太空船上的雷達儀器，他們在火星的南極平原冰層底下，探測到一片充滿鹽分的大型湖泊，這塊水體被認為是微生物生命可能的棲息地。這個偵測到的天然水庫直徑約二十公里，呈圓弧狀三角形，位於冰層表面下一點五公里處，是火星上第一次發現的穩定液態水體。
地球以外是否還有任何地方存有生命，這是科學界的終極問題之一，而這項發現儘管並非決定性物證，卻仍然提供吊人胃口的線索。水被視為生命的基本要素。研究人員表示，可能需要花上數年的時間，才能證實是否真有某種東西生存在這塊像地球冰下湖的水體中，或許未來的任務之一就是鑽透冰層，對底下的水進行抽樣檢測。
這篇發表於期刊《科學》的研究，其主持人羅貝托‧歐洛賽伊是義大利國家天文物理研究所的行星科學家，他表示：「這是火星上所找到最像棲息地的一個地方，生命或許能夠在此延續。」歐洛賽伊補充說：「像這樣的環境不太會是你的理想度假地點，或是會有魚類游來游去的地方。」他指出：「事實上，仍然有地球上的有機體可以在類似的環境中存活並繁衍。地球上甚至也有微生物能在冰裡存活。」
這項發現是借助於歐洲太空總署的「火星快車號」太空船上一台儀器在二○一二年五月到二○一五年十二月之間蒐集到的數據。這台儀器發送出雷達的脈衝波，能穿透火星表面與冰冠層。這份研究的共同作者恩利可‧法拉米尼是義大利太空總署的主任科學家，他在研究過程中表示：「我們耗費多年時間分析數據，努力找出一個正確的方法，以確認觀測的對象是毫無疑問的液態水。」這個地點的雷達數據與地球上南極洲與格陵蘭冰原底下發現的冰下湖非常相似。
很久以前，火星比現在溫暖且潮濕，表面乾涸的湖床與河谷也證明以前有相當大量的水體存在。也曾有跡象顯示目前火星上有液態水，包括受爭議的火星山坡水活動證據，但都不是穩定的水體。歐洛賽伊指出，火星湖裡的水溫度低於正常的冰點，但仍維持液態的一大部分原因可歸因於大量鹽分。他也估計湖水溫度約在攝氏零下十度到零下七十度之間。
歐洛賽伊表示，未來是否還會發現更多火星表面下的天然水庫，或是這個新發現其實是某種特殊情況，這都還需要繼續觀察。他指出，如果偵測到其他水體，並發現像地球上有一個冰下湖網絡存在，那可能暗示液態水已經持續存在了數百萬年，甚至能追溯到三十億至五億年前當火星是一個更適合居住的行星。
歐洛賽伊補充說，問題在於火星上是否有任何形式的生命，在很久以前就已開始演化，並找到方式存活至今。他表示：「沒有人敢說火星上會不會還有其他更複雜的生命形式。」
（台北時報章厚明譯）
Street lights are often taken for granted until a power outage plunges the world into darkness. When that happens, the value of these lighting installations becomes evident as the world turns into a more dangerous place for pedestrians and motorists alike. The Chinese could claim to be the first to have constructed a crude type of street light. Around 500 BC, residents of Beijing employed a type of street lamp that used hollow bamboo pipes and natural gas vents to create burning torches. Later, ancient Romans adopted lamps fueled by vegetable oil, which relied on slaves to light and
A: Who else is on Billboard’s list: “The 25 greatest pop stars of the 21st Century?” B: No. 15 to 6 are: Miley Cyrus, Justin Timberlake, Nicki Minaj, Eminem, Usher, Adele, Ariana Grande, Justin Bieber, Kanye West and Britney Spears. A: I can’t believe that Adele’s only at No. 10. B: No. 5 to 1 are: Lady Gaga, Drake, Rihanna, Taylor Swift and Beyonce. A: Well, they surely deserve the honor. A: 《告示牌》雜誌的「21世紀最偉大的25位流行歌手」，還有誰上榜啊？ B: 第15至6名是：麥莉希拉、大賈斯汀、妮姬米娜、阿姆、亞瑟小子、愛黛兒、亞莉安娜、小賈斯汀、肯伊威斯特、小甜甜布蘭妮。 A: 真不敢相信愛黛兒只排第10名。 B: 第5至1名是：女神卡卡、德瑞克、蕾哈娜、泰勒絲、碧昂絲。 A: 這幾位真是實至名歸！ （By Eddy Chang, Taipei Times／台北時報張聖恩）
Undersea cables are conductors wrapped in insulating materials and laid on the seabed. Their main functions are telecommunications or power transmission. The core of the undersea cables used for Internet signals is optical fiber, using light to transmit Internet signals. Taiwan’s communications are currently handled by 10 domestic undersea cables and 14 international undersea cables. About 99 percent of Taiwan’s Internet bandwidth relies on undersea cables, making them Taiwan’s “digital lifeline.” The demands on the cables’ bandwidth are only set to increase with the development of artificial intelligence (AI), which relies on the data fed into it. Today, data is
Spoiler alert and shift blame 破梗&甩鍋 在新冠疫情期間，無論是因為封城 (lockdown) 還是居家隔離 (self-isolation at home)，人們關在家中使用網路的時間大增。這也讓一些原本只存在於網路論壇的用語廣為普及。我們來談一下破梗 (spoiler alert) 與甩鍋 (shift blame) 這兩個用語。 有位古典文學教授 Joel Christensen 針對領導統御與疫情控制寫了一篇以古喻今、相當深入的文章：“Plagues follow bad leadership in ancient Greek tales”，文中出現一些講法，可用來翻譯上述的流行語： In the 5th century B.C., the playwright Sophocles begins Oedipus Tyrannos with the title character struggling to identify the cause of a plague striking his city, Thebes. (Spoiler alert: It’s his own bad leadership.) (Joel Christensen, “Plagues follow bad leadership in ancient Greek tales,” The Conversation, March 12, 2020) 作者提到 Oedipus（伊底帕斯）想找出瘟疫何以降臨他的城邦的緣由，加了一句：Spoiler alert: It’s his own bad leadership.（破梗：領導無方）。Spoiler alert 就是「破梗」，如果用在有人洩漏電影劇情的情境中，也可以翻作「小心爆雷」或「劇透警告」。疫情之下，在家看影集、電影成了很多人的娛樂，但要小心劇透 (spoilers)，很多 YouTube 上的影評在開頭也都會說 Spoiler alert!，警告還沒看過電影的觀眾小心爆雷、劇透。 至於「甩鍋」，源自大陸網民用語，通常意指某人犯了錯之後想推卸責任、轉移焦點、甚至讓別人背黑鍋的做法。疫情爆發後，相關網路資訊量爆增，許多中國網民也想找人為這場疫情負責，紛紛呼籲地方政府首長、地方黨書記不要「甩鍋」。 其實，在古代文學《奧德賽》中，就有「將自己的責任怪罪眾神」的說法，試用時下流行的「甩鍋」來重新翻譯： Humans are always blaming the gods for their suffering, but they experience
RSS