美國(guó)宇航局“藏寶圖”展示了火星上的水

美國(guó)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(jù)在不斷增加。因?yàn)樗畬?duì)于我們所知道的生命是如此重要，這對(duì)我們把人類送到離家更遠(yuǎn)的地方以及尋找外星生命的跡象來(lái)說(shuō)是個(gè)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(guó)宇航局解釋說(shuō)，液態(tài)水在稀薄的火星空氣中不能維持很長(zhǎng)時(shí)間，而是在暴露于大氣中時(shí)迅速蒸發(fā)。科學(xué)家們已經(jīng)在火星中緯度地區(qū)的地下深處發(fā)現(xiàn)了冰凍水的證據(jù)，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(wù)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(zhuǎn)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(shí)候，歐洲航天局(ESA)和火星快車項(xiàng)目的研究人員宣布，他們不僅發(fā)現(xiàn)了火星北半球環(huán)形山中有水流動(dòng)的歷史證據(jù)，而且還發(fā)現(xiàn)了一個(gè)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(xiàn)非常重要;它們幫助我們識(shí)別火星上最有希望發(fā)現(xiàn)過(guò)去生命跡象的區(qū)域。歐洲航天局火星快車項(xiàng)目的科學(xué)家德米特里·提托夫說(shuō)。

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(jù)。在歐空局火星快車上利用火星先進(jìn)雷達(dá)探測(cè)地下和電離層測(cè)深儀(MARSIS)，雷達(dá)探測(cè)到一個(gè)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(shí)MARSIS的發(fā)現(xiàn)。

Liquid water or flowing sand?

液態(tài)水還是流動(dòng)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(guó)國(guó)家航空航天局(NASA)公布了在這顆紅色星球上存在流動(dòng)的季節(jié)性液體水的證據(jù)，盡管后來(lái)的進(jìn)一步研究對(duì)這一解釋提出了質(zhì)疑，沙子還是灰塵。美國(guó)國(guó)家航空航天局在一份聲明中承認(rèn)了這一點(diǎn)，盡管它指出這些結(jié)論背后的線索“仍然令人費(fèi)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(xué)》上的一項(xiàng)研究，該研究表明，科學(xué)家們能夠在地球表面研究RSL。這些條紋以前在照片中出現(xiàn)過(guò)，但是因?yàn)檫@些條紋只有5米(16英尺)寬，研究人員無(wú)法得到足夠好的觀察來(lái)確定是什么導(dǎo)致了這些條紋。然而，最終他們找到了一種分析火星勘測(cè)軌道飛行器數(shù)據(jù)的方法，即從圖片中按像素提取數(shù)據(jù)。這使得科學(xué)家們可以研究這顆紅色星球表面的更小的細(xì)節(jié)，這些細(xì)節(jié)提供了新的信息。