美國宇航局“藏寶圖”展示了火星上的水

美國宇航局“藏寶圖”展示了火星上的水

The evidence of water on Mars continues to grow. And because water is so important for life as we know it, this bodes well for our efforts both to send humans farther from home and to search for signs of extraterrestrial life.

火星上有水的證據在不斷增加。因為水對于我們所知道的生命是如此重要，這對我們把人類送到離家更遠的地方以及尋找外星生命的跡象來說是個好兆頭。

This map shows underground water ice on Mars. Cool colors are closer to the surface, and the outlined box represents the ideal region to send astronauts for them to dig up water ice. (Photo: NASA/JPL-Caltech/ASU)

Liquid water can't last very long in the thin Martian air, instead quickly evaporating when exposed to the atmosphere, NASA explains. Scientists have found evidence of frozen water deeper underground at the planet's mid-latitudes, but this new image maps out shallower — and thus more accessible — water ice. Rather than trying to move large amounts of water from Earth, any human missions to Mars will likely need to harvest this kind of ice for drinking water and other purposes.

美國宇航局解釋說，液態(tài)水在稀薄的火星空氣中不能維持很長時間，而是在暴露于大氣中時迅速蒸發(fā)?？茖W家們已經在火星中緯度地區(qū)的地下深處發(fā)現了冰凍水的證據，但這張新的圖像描繪出了更淺的水冰，因此也更容易接近。人類前往火星的任何任務都可能需要收集這種冰，以供飲用和其他用途，而不是試圖從地球上轉移大量的水。

Underground lakes

地下湖

Craters on Mars hint at a system of interconnected lakes running underground. (Photo: NASA)

Earlier in 2019, researchers from the European Space Agency (ESA) and the Mars Express project announced they had not only found historical evidence of water flowing in craters around Mars' northern hemisphere, but also that a system of ancient, interconnected lakes lurks underground.

2019年早些時候，歐洲航天局(ESA)和火星快車項目的研究人員宣布，他們不僅發(fā)現了火星北半球環(huán)形山中有水流動的歷史證據，而且還發(fā)現了一個古老的相互連接的湖泊系統(tǒng)潛伏在地下。

"Findings like this are hugely important; they help us to identify the regions of Mars that are the most promising for finding signs of past life," said Dmitri Titov, ESA’s Mars Express project scientist.

“這樣的發(fā)現非常重要;它們幫助我們識別火星上最有希望發(fā)現過去生命跡象的區(qū)域。歐洲航天局火星快車項目的科學家德米特里·提托夫說。

Polar ice caps

極地冰蓋

NASA/ESA Hubble Space Telescope snapped this portrait of Mars, which shows the southern polar ice cap at the bottom. (Photo: NASA/ESA, J. Bell (Cornell U.) and M. Wolff (SSI))

In 2018, the Italian Space Agency announced evidence of liquid water underneath Mars' southern polar ice cap. Using the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument (MARSIS) aboard the ESA's Mars Express spacecraft, radar detected a subglacial lake roughly 20 km (12.5 miles) wide and 1.6 km (1 mile) below the surface.

2018年，意大利航天局公布了火星南部極地冰蓋下液態(tài)水的證據。在歐空局火星快車上利用火星先進雷達探測地下和電離層測深儀(MARSIS)，雷達探測到一個冰下湖泊，大約20公里(12.5英里)寬，1.6公里(1英里)深。

Other experts, however, were not immediately able to confirm MARSIS' findings.

然而，其他專家并不能立即證實MARSIS的發(fā)現。

Liquid water or flowing sand?

液態(tài)水還是流動的沙子?

These dark streaks, called recurring slope lineae (RSL), flow downhill at several locations on the surface of Mars. Initially thought to be signs of liquid water, they may also be caused by 'granular flows' of sand and dust, research suggests. (Photo: NASA/JPL/University of Arizona)

In 2015, NASA announced evidence of liquid, flowing seasonal water on the red planet, although further research later cast doubt on that interpretation, suggesting what seemed like evidence of flowing water might actually be caused by "granular flows" — i.e., sand or dust. NASA acknowledged this in a statement, although it noted the clues behind these dueling conclusions "remain puzzling."

2015年，美國國家航空航天局(NASA)公布了在這顆紅色星球上存在流動的季節(jié)性液體水的證據，盡管后來的進一步研究對這一解釋提出了質疑，沙子還是灰塵。美國國家航空航天局在一份聲明中承認了這一點，盡管它指出這些結論背后的線索“仍然令人費解”。

This image shows RSL on the walls of Garni crater, where the dark streaks are up to a few hundred meters in length. (Photo: NASA/JPL/University of Arizona)

The news was based on research published in Nature Geoscience, which showed how scientists were able to study RSL on the planet's surface. These streaks had been previously seen in photos, but because the streaks are only about 5 meters (16 feet) across, researchers couldn't get a good enough look to determine what was causing them. Eventually, however, they found a way to analyze data from the Mars Reconnaissance Orbiter by extracting data from the pictures on a per pixel level. This let scientists study smaller details on the red planet's surface, and those details provided the new information.

這一消息是基于發(fā)表在《自然地球科學》上的一項研究，該研究表明，科學家們能夠在地球表面研究RSL。這些條紋以前在照片中出現過，但是因為這些條紋只有5米(16英尺)寬，研究人員無法得到足夠好的觀察來確定是什么導致了這些條紋。然而，最終他們找到了一種分析火星勘測軌道飛行器數據的方法，即從圖片中按像素提取數據。這使得科學家們可以研究這顆紅色星球表面的更小的細節(jié)，這些細節(jié)提供了新的信息。