Meet the Endoterrestrials

遇見地底生物

Hydrogen sulfide—a gas found in sewers, in your intestines, and, apparently, underground in Oman—is produced by microbes living in the absence of oxygen. Deprived of that life-giving gas, they pull a trick that no animal on Earth can do: They breathe something else. In other words, they burn their food using some other chemical that is available underground.

硫化氫是一種存在于下水道、腸道——顯然還有阿曼地下的氣體，它是由生活在缺氧環(huán)境中的微生物產(chǎn)生的。沒有了那種能維持生命的氣體，它們就會(huì)做出地球上任何動(dòng)物都做不到的事情：呼吸其他東西。換句話說(shuō)，它們用地下可利用的其他化學(xué)物質(zhì)燃燒食物。

The sections of core brought up so far offered clues about what they might be breathing. The gassy core was crisscrossed by bands of orange-brown stone—marking the places where hot magma had spurted through deep fissures in the Earth millions of years before, when this rock lay miles underground.

到目前為止發(fā)現(xiàn)的巖芯提供了它們可能是怎樣呼吸的線索。這個(gè)冒氣的巖芯上面是縱橫交錯(cuò)的橘黃色的條紋，這些條紋標(biāo)識(shí)出了數(shù)百萬(wàn)年前熾熱的巖漿從地下幾英里處的深裂縫中噴出來(lái)的地方。

Those bands of fossil magma would have gradually bled their chemical components into the groundwater—including a molecule called sulfate, which consists of a single sulfur atom studded with four oxygen atoms. The microbes were probably using this molecule to digest hydrogen, said Templeton: “They eat the hydrogen and they breathe the sulfate.” And then, they exhale fart gas.

這些化石巖漿帶的化學(xué)成分會(huì)逐漸滲入地下水，其中包括一種叫做硫酸鹽的分子，它由一個(gè)硫原子和四個(gè)氧原子組成。坦普爾頓說(shuō)，這些微生物可能利用這種分子來(lái)消化氫，“它們吃掉氫，呼吸硫酸鹽”。然后，它們呼出的是屁。

Hydrogen sulfide isn’t just stinky. It is also toxic. So the very microbes that produce it also run the risk of poisoning themselves as it accumulates underground. How did they avoid doing so? Once again, the rock provided clues.

硫化氫不僅是臭的，它還是有毒的。因此，產(chǎn)生這種物質(zhì)的微生物也有讓自己中毒的危險(xiǎn)，因?yàn)樗鼤?huì)在地下積聚。它們是如何避免這種結(jié)果的呢？巖石再次提供了線索。

As drilling continued over the next several days, the black goo petered out. Each new section of core was dry and stink-free. But the stone itself had changed: Its mosaic of veins and serpentine minerals had darkened into shades of gray and black, like a plaid shirt soaked in ink.

在接下來(lái)的幾天里，隨著鉆探的繼續(xù)，黑色粘稠物逐漸消失。每一段巖芯都是干燥無(wú)味的。但是石頭本身已經(jīng)發(fā)生了變化：它那由紋理和蛇紋石化礦物組成的馬賽克已經(jīng)變成了灰色和黑色，就像一件浸透了墨水的格子襯衫。

“All of that blackening is a bio-product,” Templeton said one afternoon, as she and her research associate, Eric Ellison, crowded inside a cramped laboratory trailer, packing samples of rock to send home. Some of the rocks sat in a sealed Plexiglass box, and Ellison handled them with his hands inserted through gloves mounted in the walls of the box—giving the appearance that the rocks contained something sinister. But the precaution wasn’t intended to protect humans; it was meant to keep the delicate microbes out of contact with oxygen.

“所有這些變黑的結(jié)果都是一種生物產(chǎn)品，”一天下午，鄧普頓和她的研究助理埃里克·埃里森擠在一輛狹窄的實(shí)驗(yàn)室拖車?yán)?，她如此說(shuō)道。他們正在打包巖石樣本，準(zhǔn)備送回家。有些石頭放在一個(gè)密封的有機(jī)玻璃盒子里，埃利森把戴著手套的手伸進(jìn)盒子取石頭，看上去石頭里藏著什么兇惡的東西。但這種預(yù)防措施并不是為了保護(hù)人類；它的目的是讓這些脆弱的微生物遠(yuǎn)離氧氣。

Templeton speculated that the microbes had stained the most recent rock samples: The hydrogen sulfide they exhaled had reacted with iron in the surrounding stone, creating iron sulfide—a harmless black mineral. The pyrite minerals we’d seen earlier were also composed of iron and sulfide, and could have formed the same way.

坦普爾頓推測(cè)這些微生物對(duì)最近的巖石樣本進(jìn)行了染色：它們呼出的硫化氫與周圍巖石中的鐵發(fā)生了反應(yīng)，生成了硫化鐵——一種無(wú)害的黑色礦物。我們之前看到的黃鐵礦礦物也是由鐵和硫化物組成的，它也可能是以同樣的方式形成的。

These black minerals are more than an academic curiosity. They provide a glimpse of how microbes have not only survived inside the Earth’s crust, but also transformed it, in some cases forming minerals that might not otherwise exist.

這些黑色礦物不僅僅是學(xué)術(shù)上的奇聞?shì)W事。它們讓我們得以一窺微生物是如何在地殼內(nèi)部生存下來(lái)的，它們是如何改造地殼的，在某些情況下，它們形成了原本不可能存在的礦物質(zhì)。

Some of the world’s richest deposits of iron, lead, zinc, copper, silver, and other metals formed when hydrogen sulfide latched onto metals that had dissolved deep underground. The sulfide locked the metals in place, concentrating them into minerals that accumulated for millions of years—until they were exhumed by miners. The hydrogen sulfide that formed those ores often came from volcanic sources, but in some cases, it came from microbes.

一些世界上含量最豐富的礦藏——鐵、鉛、鋅、銅、銀和其他的金屬——是在硫化氫與溶解在地下深處的金屬結(jié)合時(shí)形成的。硫化物將金屬固定在原地，將它們濃縮成礦物，這些礦物積累了數(shù)百萬(wàn)年，直到被礦工挖掘出來(lái)。形成這些礦石的硫化氫通常來(lái)自火山，但在某些情況下，它來(lái)自微生物。

Robert Hazen, a mineralogist and astrobiologist at the Carnegie Institution in Washington, D.C., believes that more than half of Earth’s minerals owe their existence to life—to the roots of plants, to corals and diatoms, and even to subsurface microbes. He has even speculated that the world’s seven continents may owe their existence, in part, to microbes gnawing on rocks.

羅伯特·哈森是華盛頓卡內(nèi)基研究所的礦物學(xué)家和天體生物學(xué)家。他認(rèn)為，地球上一半以上的礦物的存在都?xì)w功于生命——植物的根、珊瑚和硅藻，甚至地下微生物。他甚至推測(cè)，世界上七大洲存在的部分原因可能就是微生物啃噬巖石。

Four billion years ago, Earth had no permanent land—just a few volcanic peaks jutting above the ocean. But microbes on the seafloor may have helped change that. They attacked iron-rich basalt rocks, much as they do today, converting the volcanic glass into clay minerals. Those clays melted more readily than other rocks. And once melted, they resolidified into a new kind of rock, a material lighter and fluffier than the rest of the planet: granite.

40億年前，地球上沒有永久性的陸地——只有幾座火山山峰突出海面。但是海底的微生物可能幫助改變了這一點(diǎn)。它們攻擊富含鐵的玄武巖，就像它們今天所做的一樣，將火山玻璃轉(zhuǎn)化為粘土礦物。這些粘土比其他巖**容易熔化。一旦融化，它們就會(huì)重新凝固成一種新的巖石，一種比地球上的其他部分更輕、更松軟的材料：花崗巖。

Those buoyant granites piled into heaps that rose above the ocean, creating the first permanent continents. This would have happened to some degree without the help of microbes, but Hazen suspects that they accelerated the process. “You can imagine microbes shifting the balance,” he says. “What we’re arguing is that microbes played a fundamental role.”

那些浮力大的花崗巖堆積在海面上，形成了第一個(gè)永久性的大陸。如果沒有微生物的幫助，這種情況在某種程度上也是會(huì)發(fā)生的，但是哈森懷疑微生物加速了這一進(jìn)程?！澳憧梢韵胂笪⑸锔淖兞似胶?，”他說(shuō)道，“我們認(rèn)為微生物扮演了一個(gè)基本性的角色。”

The emergence of land had a profound effect on Earth’s evolution. Rocks exposed to the air broke down more quickly, releasing trace nutrients such as molybdenum, iron, and phosphorus into the oceans. These nutrients spurred the growth of photosynthetic algae, which absorbed carbon dioxide and exhaled oxygen. Just over 2 billion years ago, the first traces of oxygen appeared in Earth’s atmosphere. Five hundred and fifty million years ago, oxygen levels finally rose high enough to support the first primitive animals.

陸地的出現(xiàn)對(duì)地球的演化產(chǎn)生了深遠(yuǎn)的影響。暴露在空氣中的巖石分解得更快，向海洋中釋放微量營(yíng)養(yǎng)物質(zhì)，如鉬、鐵和磷。這些營(yíng)養(yǎng)物質(zhì)刺激了光合藻類的生長(zhǎng)，光合藻類吸收二氧化碳并呼出氧氣。就在20億年前，地球大氣中出現(xiàn)了最初的氧氣痕跡。五億五千萬(wàn)年前，氧氣水平終于上升到足以支持第一批原始動(dòng)物的水平。

Earth’s abundant water, and its optimal distance from the sun, made it a promising incubator for life. But its evolution into a paradise for intelligent, oxygen-breathing animals was never guaranteed. Microbes may have pushed our planet over an invisible tipping point—and toward the formation of continents, oxygen, and life as we know it.

地球上豐富的水，以及它與太陽(yáng)的最佳距離，使它成為一個(gè)有希望的孕育生命的地方。但它能否進(jìn)化成為了聰明的、呼吸氧氣的動(dòng)物的天堂卻從未是確證無(wú)疑的。微生物可能已經(jīng)把我們的星球推過(guò)了一個(gè)看不見的臨界點(diǎn)——朝著我們所知道的大陸、氧氣和生命的形態(tài)推進(jìn)。

Even today, microbes continue to make, and remake, our planet from the inside out.

即使在今天，微生物仍然在從內(nèi)到外地塑造和改造我們的星球。

In some ways, the microbe underworld resembles human civilization, with microbial “cities” built at the crossroads of commerce. In Oman, the thriving oasis of stinky, black microbes sat 100 feet underground, near the intersection of several large rock fractures—channels that allowed hydrogen and sulfate to trickle in from different sources.

在某些方面，微生物的地底社會(huì)與人類文明相似，微生物的“城市”建立在商業(yè)的十字路口。在阿曼，繁榮的臭氣騰騰的黑色微生物綠洲位于地下100英尺處，它靠近幾處大型巖石裂隙的交匯處——這些裂隙允許氫和硫酸鹽從不同來(lái)源流過(guò)來(lái)。

Elisabetta Mariani, a structural geologist from the University of Liverpool in England, spent long days under the canopy, mapping these breaks in the rock. Late one morning, she called me over to see something special: a break cutting diagonally across a core, exposing two rock faces streaked in paper-thin layers of green-and-black serpentine.

英國(guó)利物浦大學(xué)的結(jié)構(gòu)地質(zhì)學(xué)家伊麗莎白花了很長(zhǎng)時(shí)間在樹冠下測(cè)繪巖石上的這些裂縫。一天上午的晚些時(shí)候，她叫我去看一些特別的東西：一條斜切巖芯的裂縫，其中露出了兩塊巖石的表面，上面布滿了像紙一樣薄的綠黑相間的蛇紋。

“Can you see here these grooves?” she asked, in English accented with her native Italian, pointing out scratches that raked the two serpentine faces. They showed that this was more than just a passive break; it was an active fault. “Two blocks of rocks have slipped past each other along this direction,” she said, gesturing along the grooves.

“你能看到這些凹槽嗎？”她用帶著母語(yǔ)意大利語(yǔ)口音的英語(yǔ)問道，同時(shí)指著那兩塊蛇形表面上的劃痕。它們證明了這不僅僅是一次被動(dòng)的斷裂；這是一個(gè)活動(dòng)斷層?！皟蓧K巖石沿著這個(gè)方向相互滑過(guò)，”她指著凹槽說(shuō)道。

Tullis Onstott, a geologist at Princeton University not affiliated with the Oman drilling, believes that such active faults may do more than just provide routes for food to move underground—they may actually produce food. In November 2017, Onstott and his colleagues began an audacious experiment. Starting from a tunnel 8,000 feet down in the Moab Khotsong gold mine in South Africa, they bored a new hole toward a fault that lay nearly half a mile deeper still. On August 5, 2014, the fault had sparked a magnitude-5.5 earthquake. By drilling into it, Onstott hoped to test the provocative idea that earthquakes supply food to the deep biosphere.

普林斯頓大學(xué)的地質(zhì)學(xué)家圖利斯·奧斯多特認(rèn)為，這些活動(dòng)斷層不僅為食物在地下的移動(dòng)提供了通道，它們還可能會(huì)生產(chǎn)食物。2017年11月，奧斯多特和他的同事們開始了一項(xiàng)大膽的實(shí)驗(yàn)。他們從南非摩押·霍特松金礦8000英尺深的一個(gè)隧道開始，朝著一個(gè)更深近半英里的斷層挖了一個(gè)新洞。2014年8月5日，該斷層引發(fā)了5.5級(jí)地震。通過(guò)鉆探，奧斯托特希望測(cè)試這個(gè)具有顛覆性的想法，即地震為地層深處的生物圈提供了食物。

Scientists have long noticed that hydrogen gas seeps out of major faults such as the San Andreas in California. That gas is produced in part by a chemical reaction: Silicate minerals pulverized during a quake react with water and release hydrogen as a byproduct. For microbes sitting next to the fault, that reaction could result in something like a periodic sugar rush.

科學(xué)家們?cè)缇妥⒁獾綒錃鈺?huì)從主要的斷層中滲出，比如加州的圣安德烈亞斯斷層。這種氣體部分是由化學(xué)反應(yīng)產(chǎn)生的：在地震中粉碎的硅酸鹽礦物與水發(fā)生反應(yīng)，釋放出副產(chǎn)品氫。對(duì)于斷層附近的微生物來(lái)說(shuō)，這種反應(yīng)可能會(huì)引發(fā)周期性的糖果大戰(zhàn)。

In March 2018, four months after the drilling in the Moab Khotsong mine began, workers brought up a stone core that crossed the fault.

2018年3月，摩押·霍特松金礦開始鉆探四個(gè)月后，工人們挖出了一段穿過(guò)斷層的巖芯。

The rock along the fault was “pretty banged up,” says Onstott—torn with dozens of parallel fractures. The stone lining some of those cracks was crushed into fragile clay, marking recent earthquakes. Other cracks, filled with veins of white quartzite, marked older ruptures from thousands of years before.

奧斯多特說(shuō)道：斷層沿線的巖石“被撞得粉碎”，同時(shí)還有數(shù)十處平行的裂縫。其中一些裂縫里的石頭被壓成易碎的粘土，標(biāo)志著最近發(fā)生的地震。其他的裂縫則填滿了白色石英巖脈，標(biāo)志著幾千年前更古老的斷裂。

Onstott is now searching those quartzite veins for fossilized cells and analyzing the rock for DNA, in hopes of finding out what kind of microbes—if any—inhabit the fault.

奧斯多特目前正在這些石英巖脈中尋找化石細(xì)胞，并對(duì)巖石進(jìn)行DNA分析，希望能找到棲息在斷層中的微生物(如果有的話)。

More importantly, he and his colleagues have kept the borehole open—monitoring water, gases, and microbes in the fault, and taking new samples each time there’s an aftershock. “You can then see whether or not there’s a gas release,” he says, “and whether or not there’s a change in the microbial community because they’re consuming the gas.”

更重要的是，他和他的同事們保持了鉆孔的開放狀態(tài)，監(jiān)測(cè)斷層中的水、氣體和微生物，并在每次余震發(fā)生時(shí)采集新的樣本。他說(shuō):“然后你就可以看到是否有氣體釋放出來(lái)，以及微生物群落是否因?yàn)橄牧藲怏w而發(fā)生了變化。”

Even as Onstott awaits those results, he is starting to consider an even more radical possibility: that deep-dwelling microbes don’t just feed off of earthquakes, but might also trigger them. He believes that as microbes attack the iron, manganese, and other elements in the minerals that line the fault, they could weaken the rock—and prime the fault for its next big slip. Exploring that possibility would mean doing laboratory experiments to find out whether microbes in a fault can actually break down minerals quickly enough to affect seismic activity. With a scientist’s characteristic understatement, he contemplates the work ahead: “It’s a reasonable hypothesis to test.”

即使在奧斯多特等待這些結(jié)果的同時(shí)，他也已經(jīng)開始考慮一種更激進(jìn)的可能性：深海微生物不僅以地震為食，還可能引發(fā)地震。他相信，當(dāng)微生物攻擊沿?cái)鄬优帕械牡V物中的鐵、錳和其他元素時(shí)，它們會(huì)讓巖石變得脆弱，并為下一次大滑坡做好準(zhǔn)備。探索這種可能性意味著要進(jìn)行實(shí)驗(yàn)室實(shí)驗(yàn)，以查明斷層中的微生物是否能夠迅速分解礦物質(zhì)，從而影響到地震活動(dòng)。帶著科學(xué)家特有的輕描淡寫，他思考著未來(lái)的工作：“這是一個(gè)需要驗(yàn)證的合理假設(shè)”。

By January 30, the drill in Wadi Lawayni had reached a depth of 200 feet. Its motor growled in the background as Templeton and her colleague, Eric Boyd, rested in camp chairs under an acacia tree. Strewn at their feet lay the signs of other travelers who had paused in this rare island of shade—nodules of camel dung, smooth and round like leathery plums.

到1月30日，瓦迪·拉瓦尼的鉆井已經(jīng)達(dá)到200英尺的深度。當(dāng)坦普爾頓和她的同事埃里克·博伊德坐在一棵相思樹下的野營(yíng)椅上休息時(shí)，機(jī)器的馬達(dá)在背景中轟鳴。在他們的腳下，散落著其他旅行者在這個(gè)罕見的陰島停留過(guò)的痕跡——一堆堆光滑圓潤(rùn)的駱駝糞，就像閃耀著皮革般光澤的李子一樣。

“We think that this is an environment that’s important for understanding the origins of life,” said Boyd, a geobiologist from Montana State University in Bozeman. That potential, he said, is part of what lured him and Templeton to these deep-earth rocks in Oman: “We like hydrogen.”

位于博茲曼的蒙大拿州立大學(xué)的地質(zhì)學(xué)家博伊德說(shuō)，“我們認(rèn)為，這是一個(gè)對(duì)理解生命起源非常重要的環(huán)境。”他說(shuō)，正是這種潛力吸引著他和坦普爾頓來(lái)到阿曼尋找這些深埋地下的巖石：“我們喜歡氫氣”。

Both Boyd and Templeton believe that life on Earth started in an environment similar to that which lies a few yards beneath their camp chairs. They believe that life began within subsurface fractures, where iron-rich minerals gurgled out hydrogen gas as they reacted with water.

博伊德和坦普爾頓都相信，地球上的生命便始于一個(gè)類似于他們露營(yíng)椅下面幾碼的環(huán)境中。他們認(rèn)為生命起源于地下裂縫，富含鐵的礦物與水發(fā)生反應(yīng)時(shí)會(huì)噴出氫氣。

Of all the chemical fuels that existed on Earth 4 billion years ago, hydrogen would have been one of the easiest for early, inefficient cells to metabolize. Hydrogen wasn’t only produced by serpentinization, either; it was also produced—and still is, today—by the radioactive decay of elements such as uranium, which constantly splits apart water molecules in the surrounding rock. Hydrogen is so labile, so willing to break apart, that it can even be digested using sluggish o****nts, like carbon dioxide or pure sulfur. DNA studies of millions of gene sequences suggest that the forerunner of all life on Earth—the “l(fā)ast universal common ancestor,” or LUCA—probably did use hydrogen as its food, and burned it with carbon dioxide. The same might be true for life in other worlds.

在40億年前地球上存在的所有化學(xué)燃料中，氫是早期低效細(xì)胞最容易代謝的燃料之一。氫不僅是由蛇紋石化產(chǎn)生的；它也是由鈾等元素的放射性衰變產(chǎn)生的，至今仍是如此。鈾等元素不斷地分解周圍巖石中的水分子。氫是如此不穩(wěn)定，如此容易分解，以至于它甚至可以被緩慢的氧化劑消化，如二氧化碳或純硫。對(duì)數(shù)百萬(wàn)個(gè)基因序列的DNA研究表明，地球上所有生命的先驅(qū)者——“最后的共同祖先”(或稱之為“盧卡”)——可能確實(shí)以氫氣為食物，并將其與二氧化碳一起燃燒。其他世界的生命可能也是如此。

The iron minerals that exist here in Oman are common across the solar system, as is the process of serpentinization. The Reconnaissance Orbiter, a space probe now circling Mars, has mapped serpentine minerals on the Martian surface. The space probe Cassini has found chemical evidence of ongoing serpentinization deep within Saturn’s ice-covered moon, Enceladus. Serpentine-like minerals have been detected on the surface of Ceres, a dwarf planet that orbits the sun between Mars and Jupiter. Serpentine minerals are even found in meteorites, the fragments of embryonic planets that existed 4.5 billion years ago, just as Earth was being born—raising the possibility that the cradle of life’s origin actually existed before our planet did.

存在于阿曼的鐵礦在整個(gè)太陽(yáng)系都很常見，蛇紋石化的過(guò)程也是如此。目前環(huán)繞火星運(yùn)行的太空探測(cè)器“勘測(cè)軌道飛行器”繪制了火星表面蛇紋石化礦物的分布地圖。太空探測(cè)器卡西尼號(hào)在土星被冰覆蓋的衛(wèi)星土衛(wèi)二深處發(fā)現(xiàn)了蛇紋石化的化學(xué)證據(jù)。在谷神星——一顆圍繞太陽(yáng)運(yùn)行的矮行星，位于火星和木星之間——表面也發(fā)現(xiàn)了蛇紋石化礦物。蛇紋石化礦物甚至在隕石中也被發(fā)現(xiàn)了蹤跡，而隕石則是45億年前存在的行星胚胎的碎片，當(dāng)時(shí)地球才剛剛誕生——這增加了生命起源的搖籃實(shí)際上比我們的星球更早存在的可能性。

Hydrogen—an energy source for nascent life—was produced in all of these places. It is probably still being produced throughout the solar system.

所有這些地方都產(chǎn)生了氫——一種生命初期的能源。它可能仍在整個(gè)太陽(yáng)系的各處產(chǎn)生。

To Boyd, the implications are breathtaking.

對(duì)博伊德來(lái)說(shuō)，其影響是驚人的。

“If you had rock like this, at a temperature similar to Earth, and you had liquid water, how inevitable do you think life is?” he asked. “My personal belief is, it’s inevitable.”

“如果你有像這樣的巖石，溫度和地球相似，還有液態(tài)水，你認(rèn)為生命是不可避免的嗎？”他問道，“我個(gè)人認(rèn)為，這是不可避免的?！?br/>
Finding that life will be a challenge. With existing technologies, a probe sent to Mars could drill no more than a few feet below its hostile surface. Those shallow rocks might contain signs of past life—perhaps desiccated carcasses of Martian cells, sitting inside the microscopic tunnels that they chewed into the minerals—but any living microbes are likely to be buried hundreds of feet deeper. Templeton has grappled with the problem of detecting past signs of life—and of distinguishing those signs from things that happened without the influence of life—ever since she started looking at basaltic seafloor glasses 16 years ago.

發(fā)現(xiàn)這種生命將是一個(gè)挑戰(zhàn)。根據(jù)現(xiàn)有技術(shù)，發(fā)射到火星的探測(cè)器只能鉆探到其不友好的表面以下幾英尺的地方。這些淺層巖石可能含有過(guò)去生命存在的跡象——也許是干燥的火星細(xì)胞尸體，躺在它們咀嚼礦物的顯微隧道里——但是任何活著的微生物都可能被埋在更深的幾百英尺的地方。自從16年前坦普爾頓開始研究玄武巖海底玻璃以來(lái)，她一直在努力解決探測(cè)過(guò)去的生命跡象的問題，以及如何將這些跡象與不受生命影響的事物區(qū)分開來(lái)。

“My job is to find bio-signatures,” she says. As she studies the rocks drilled out of Oman, she’ll subject them to some of the same tools that she used on the glasses. She will bounce X-rays off the mineral surface in order to map how the microbes are altering the minerals, and whether they are leaving metals in place or etching them away. By learning how living microbes chew on minerals, she hopes to find reliable ways of identifying those same chemical chew marks in extraterrestrial rocks that haven’t held living cells for thousands of years.

“我的工作是尋找生物的簽名，”她說(shuō)道。當(dāng)她研究從阿曼鉆出來(lái)的巖石時(shí)，她會(huì)使用一些她在眼鏡上用過(guò)的工具來(lái)對(duì)付它們。她將從礦物表面反射X光，以繪制微生物如何改變礦物，以及它們是將金屬留在原地還是蝕刻它們。通過(guò)研究活微生物如何咀嚼礦物質(zhì)，她希望能找到可靠的方法來(lái)識(shí)別外星巖石中那些數(shù)千年來(lái)沒有活細(xì)胞的化學(xué)咀嚼痕跡。

One day, these tools might be packed onto a Mars rover. Or they might be used on rocks that are brought back from other worlds. For now, she and her colleagues have plenty to do in Oman, figuring out what inhabits the dark, hot, hidden biosphere below their feet.

有一天，這些工具可能會(huì)被打包到火星探測(cè)器上?；蛘咚鼈兛赡鼙挥迷趶钠渌澜鐜Щ貋?lái)的巖石上。目前，她和她的同事們?cè)诎⒙泻芏嗍虑橐?，他們要弄清楚在他們腳下黑暗、炎熱、隱秘的生物圈里棲息著什么。