of 2021. And one of its main jobs?

的2021年。其主要工作之一是?

Finding signs of ancient microbial life on Mars.

在火星上發現古微生物生命的跡象。

But wait, haven't we already found signs?

但是，等等，我們不是已經發現了跡象嗎？

What more evidence do we need, and how much do we actually have so far?

我們還需要什麼證據，目前我們到底有多少證據？

Now, before we get into actual life forms, we have to talk about water.

現在，在我們進入實際的生命形態之前，我們必須先談談水。

Most astrobiologists agree that liquid water, or at least some kind of liquid solvent, is

大多數天體生物學家都認為，液態水，或至少是某種液態溶劑，是一個很好的選擇。

arguably the most important variable in our continued search for life everywhere, including on Mars.

可以說是我們繼續尋找各地生命的最重要變量，包括火星上的生命。

For a long time, the best image we had that indicated the prior presence of water was

很長一段時間裡，我們擁有的最好的影像，表明事先存在的水是：

this picture.

這幅畫。

It's possible that this riverbed and canyon formation could have also resulted from wind

這種河床和峽谷的形成也有可能是風的結果。

flow, glacial ice, volcanic lava, or liquefied CO2, but experts believe that the best explanation

冰川流、冰川冰、火山熔岩或液化的二氧化碳，但專家認為最好的解釋是：

for this very specific shape and pattern was repeatedly flowing water.

對於這種非常特殊的形狀和圖案是反覆的流水。

There are lots of other convincing geological features on the surface of Mars that make

火星表面還有很多其他令人信服的地質特徵，這使得。

a pretty strong case for the fact that the planet may have once had flowing, liquid water.

一個相當強大的案例證明了這個星球可能曾經有流動的液態水的事實。

Plus in 2012, the Curiosity Rover phoned home to tell us it had found and examined a number

再加上2012年，好奇號漫遊車打電話回家，告訴我們它發現並檢查了一些。

of rocks that we now know were exposed to water billions of years ago.

我們現在知道的數十億年前暴露在水中的岩石。

But what about water on Mars that's liquid right now?

但現在火星上的水是液態的呢？

The High Resolution Imaging Science Experiment or HiRISE camera aboard the Mars Reconnaissance

火星偵察機上的高分辨率成像科學實驗（HiRISE）相機。

Orbiter took pictures that showed us something we now call recurring slope linea,

Orbiter拍攝的照片向我們展示了一些我們現在稱之為反覆坡線的東西。

or RSL.

或RSL。

These dark streaks seem to fluctuate over time, appearing to flow down steep Martian slopes.

這些黑暗的條紋似乎隨著時間的推移而波動，似乎從陡峭的火星斜坡上流下。

And this discovery made a huge splash at the time and was widely hailed as evidence of current

而這一發現在當時引起了巨大的轟動，被廣泛譽為當前的證據。

water on Mars, but there are lots of voices who push back on this, saying it's unrealistic

火星上的水，但也有很多聲音對此進行了反駁，認為這是不現實的

to imagine that Mars could support flowing liquid water when its atmosphere is so thin

想象一下，火星的大氣層如此稀薄，卻能支持流動的液態水。

and so cold.

而且還這麼冷。

And new work argues that instead of water, it could be granular flow of sand and dust

而新的工作認為，它可能不是水，而是顆粒狀的沙塵流。

that makes these marks.

做出這些標記的。

So the debate about whether RSL indicate current flowing water on Mars still continues today.

所以，關於RSL是否表示火星上有水流的爭論至今仍在繼續。

There's also super cool evidence of liquid oceans inside Mars right now, but that's

現在火星內部也有超酷的液態海洋證據，但那是... ...

kinda a whole separate video.

有點整個單獨的視頻。

And say we put water to the side entirely...what evidence do we have of actual life forms on Mars?

而且說我們把水完全放在一邊......我們有什麼證據證明火星上有實際的生命形式？

The biggest and most controversial is the infamous incident in 1996 when NASA announced

最大的也是最有爭議的是1996年的臭名昭著的事件，當時NASA宣佈了

they had found evidence of extraterrestrial life inside a meteorite that thudded to Earth

他們在一顆砸向地球的隕石中發現了外星生命的證據。

from Mars.

來自火星的。

The 'proof'?

證據"？

The combination of minerals and carbon compounds inside the meteorite seemed remarkably similar

隕石內部的礦物和碳化合物的組合似乎非常相似。

in makeup and form to what some microbes produce here on Earth.

在構成和形式上與地球上的一些微生物所產生的一樣。

That's what we call a biosignature.

這就是我們所說的生物簽名。

But in the years since, scientists have pointed out that non-living or abiotic processes are equally

但在此後的幾年裡，科學家們指出，非生物或非生物過程同樣是

likely to have produced the same clumps of minerals that we were so excited to call fossilized

很可能產生了與我們興奮地稱之為化石的礦物質團。

evidence of life.

生命的證據。

Plus, follow-on work did find that the meteorite had been contaminated by Earth's bacteria once it got here.

另外，後續的工作確實發現，隕石到了這裡之後，已經被地球的細菌汙染了。

So...eh?

那麼...

Over twenty years later, the debate still rages on.

二十多年過去了，這場爭論仍在繼續。

But even though it didn't give us a particularly satisfying answer, this meteorite did ignite

但儘管它沒有給我們一個特別滿意的答案，但這塊隕石確實點燃了

a very important conversation.

一個非常重要的對話。

See one of the issues here is that we don't have a very standard definition of what life is.

你看這裡的一個問題是，我們對生命的定義沒有一個很標準的定義。

And that makes finding definitive evidence of it...kinda hard.

而這就使得尋找確切的證據......有點難。

Other Martian missions have found traces of methane and formaldehyde on Mars, which are

其他火星任務在火星上發現了甲烷和甲醛的蹤跡，這些都是。

both produced by living things here on Earth...although they can be produced by non-living processes.

都是由地球上的生物產生的......雖然它們可以由非生物過程產生。

And again, we have a kinda philosophical dilemma here because we only know how to look for

而我們在這裡又遇到了一個挺哲學的難題，因為我們只知道如何去尋找

the things we know about.

我們知道的事情。

It could be that life elsewhere in the solar system or the universe is marked by biosignatures that we

可能是太陽系或宇宙中其他地方的生命都有生物特徵，而我們

don't know about or don't know how to look for... yet.

不知道或不知道如何尋找... 還沒有。

And then there's the whole question of where did life on Mars come from?!

還有一個問題就是火星上的生命從何而來？

I mean...existential issues abound.

我是說......存在的問題很多。

Now, given the fact that we've been studying Mars from home since the 1600s and from space

現在，考慮到我們從16世紀起就從國內研究火星，從太空研究火星的事實。

since the 60s, what I've covered in this video is certainly not exhaustive.

自60年代以來，我在這段視頻中所涉及的內容當然並不詳盡。

But it is a short summary of the most compelling evidence we currently have for

但這是我們目前所掌握的最有說服力的證據的一個簡短總結

life on Mars which...even after all that, are still just tiny hints on where to start.

火星上的生命，這......即使在所有這些之後，仍然只是微小的提示，從哪裡開始。

Nothing definite, but hopefully a good base from which to make progress.

沒有明確的目標，但希望能有一個良好的基礎，在此基礎上取得進展。

Now when it lands, Perseverance will be happily digging around in Mars' rocks for fossils, gathering samples

現在，當它著陸後，"鍥而不捨 "將在火星的岩石中快樂地挖掘化石，採集樣本。

to hang onto until future missions can hopefully ferry those samples back to Earth for further

直到未來的飛行任務有希望將這些樣本運回地球做進一步的研究。

study.

研究。

And it'll eventually be joined by the European-Russian ExoMars rover.

而它最終會被歐洲俄羅斯的ExoMars探測器加入。

Some scientists are also pushing for these bots to search for genetic signs of current

一些科學家也在推動這些機器人搜索當前的遺傳跡象。

life on Mars too!

火星上也有生命！

But whatever we look for, from the years past it's pretty clear that whatever we find is going

但無論我們找什麼，從過去幾年的情況來看，很明顯，無論我們找到什麼，都是要的

to need to be really solid evidence before we make any solid claims, and it may require

在我們提出任何堅實的要求之前，需要真正的證據，它可能需要。

a whole re-imagining of our frameworks for—and classification of—life itself.

對我們的生活框架和生活本身的分類進行了整體的重新想象。

Because as Carl Sagan said, “extraordinary claims require extraordinary evidence”.

因為正如卡爾-薩根所說，"非凡的主張需要非凡的證據"。

Which, it's pretty safe to say, we haven't quite found...yet.

可以肯定地說，我們還沒有找到... ...還沒有。

If you want more info on all you could ever want to know about the Mars Rover, then check out

如果你想了解更多關於火星探測器的資訊，那麼請看一下

this video here, and make sure you subscribe to Seeker for all your space exploration news

這個視頻在這裡，並確保你訂閱Seeker的所有空間探索新聞。

and updates with our series Countdown to Launch.

以及我們的系列發佈會倒計時的更新。

If you have questions about specific Mars discoveries, let us know down in the comments below.

如果你有關於具體火星發現的問題，請在下面的評論中告訴我們。

As always thanks for watching, and I'll see next time.

一如既往的感謝大家的觀看，我們下次再見。