塞巴斯蒂安·埃切韋里

Inspired by science fiction and a strange phenomenon on the Martian surface， researchers have discovered a way that Earth life could survive on the red planet.

A team of scientists at Harvard University， the University of Edinburgh， and NASAs Jet Propulsion Laboratory have found that a material called aerogel1 can trap enough heat from sunlight to create regions of liquid water and Earth-like temperatures on Mars. This technology， they say， could be adapted to build human habitats in the not-so-distant future.

In a new study， the researchers show that placing a thin layer of a translucent aerogel—just a few centimeters thick—atop Mars surface could heat the ground by up to 50 degrees Celsius， or 90 degrees Fahrenheit， or more. This would be enough to thaw2 water previously frozen underground， providing the crucial ingredient to support life.

Just like carbon dioxide and other greenhouse gases， the aerogel allows visible light to pass through and warm up the ground， but makes it harder for infrared light—which humans cannot see， but experience as heat—to escape. Thanks to its unique structure， aerogel produces a much more efficient greenhouse effect than carbon dioxide.

“Jelly3 [is] a structure [made] of a solid filled with [tiny pockets of] liquid. If you suck out all the liquid and replace it with air， you get an aerogel，” said Laura Kerber， a research scientist4 at the Jet Propulsion Laboratory.

These air pockets are the key to heating up Mars. “Air is really bad at conducting heat， but it usually moves around and brings heat from place to place. But since [in the aerogel] its trapped in all these tiny pockets， then [the air] cant mix around， and that makes it a great insulator，” she said. A similar type of aerogel is used to insulate the Curiosity rover currently exploring Mars， as well as deep sea pipes， firefighting equipment， and even houses here on the Earth.

Scientists could deploy the aerogel on a small-scale first and then work up to5 more ambitious projects. “The simplest one... is to make [an aerogel] blanket and allow algae and microbial life [from Earth] to grow. Habitats for humans—it would still absolutely work， but youd have to combine [the aerogel] with other materials，” said Robin Wordsworth， an associate professor of environmental science and engineering at Harvard.

“In its current form， [the aerogel] is pretty brittle，” Kerber said. Mars atmosphere is very thin and toxic to most Earth life， so any habitable structure would have to be airtight. She explained that in the future， tiles made of aerogel sandwiched between strong plexiglass could be used to make a pressurized6 dome for humans.

Because these Earth-life environments would be self-contained7， they would also preserve whatever Martian life that might exist. “Nobody wants to go to Mars and kill the only other life we find by out-competing8 it with Earth life. This is a nice solution; piece by piece， little contained island of habitability， we can live there and [not] mess it up，” Kerber said.

“This， we think， for the first time， is a local and scalable9 way to approach achieving Martian habitability. There are many challenges. But we think it is very exciting that this is now a possibility in our lifetime，” Wordsworth said.

This finding， exciting as it is， is only the latest in a story that began far before humans even walked on the moon.

“The science fiction I started my life with [is] coming true，” said Edward Guinan， a professor of astrophysics and planetary science at Villanova University. For more than a century， science fiction authors have been writing about human settlements on the red planet， depicted as having breathable air， liquid water， and advanced alien life.

Humanitys understanding of Mars took a leap forward in 1965， when the Mariner 4 probe took the first close-up photos and found that Mars was entirely inhospitable to humans—deserted， dry， and with a dangerously thin atmosphere.

But writers and scientists—many inspired by their favorite novels—didnt give up. Instead， they focused on terraforming10： using technology to radically transform Mars into a place where people could survive.

In 1971， Carl Sagan11 proposed vaporizing all of the frozen water12 and carbon dioxide of Mars ice caps. The resulting gas would then heat the planet by the same greenhouse effect behind Earths own global warming crisis. But in 2018， NASA discovered that there was not enough frozen water and carbon dioxide on Mars for this plan to work without incredibly advanced technology.

Harvards Wordsworth felt pushed13 to think practically about terraforming. “[We asked] what actually could work and what couldnt in our lifetime， as opposed to far in the future，” he said.

The direct inspiration for the aerogel project， however， came from Mars itself.

The same heating process “already happens on Mars right now， but with [frozen carbon dioxide]. Its pretty transparent， and accumulates on dunes. The sun shines through， and gas starts forming. And it finally explodes， and you get these geysers14 of [carbon dioxide] that leave black spots. Happens every spring，” said Kerber.

Having studied the Martian surface， Kerber has already discovered the ideal spot to build a human settlement.

“I know where all of the subsurface water is on the planet. Theres this place called Deuteronilus Mensae15. If you want to do this， this is where Id put your domes; this is where theres water close to the surface，” she said.

As for what those living in aerogel-heated habitats on Mars might eat， Guinan and his astrobotany students are working on it. “We have a greenhouse in Villanova. We are growing plants in Martian simulated soil， [and] under the light conditions we get on Mars，” he said.

Guinan already plans for his students to experiment with growing their “Mars Garden” in an aerogel-based greenhouse. “I already bought [aerogel]. We are actually going to try it，” he said.

Having worked in astrophysics for over 50 years， Guinan is hopeful that this new technology will see humans living and growing food on Mars within his lifetime.

Kerber believes that solving the remaining challenges—the largest of which is the trip to Mars itself—is only a matter of funding. “If someone said， ‘Heres a bunch of money， and go do it， wed do it. People think its so far out of reach， or something from a sci-fi film—its not. Let us try，” she said.

受科幻小說(shuō)和火星表面奇觀的啟發(fā)，研究人員發(fā)現(xiàn)了一種能讓地球生命在這顆紅色行星上生存的方法。

來(lái)自哈佛大學(xué)、愛(ài)丁堡大學(xué)和美國(guó)國(guó)家航空航天局噴氣推進(jìn)實(shí)驗(yàn)室的科學(xué)家組成的團(tuán)隊(duì)發(fā)現(xiàn)，一種叫作氣凝膠的材料能從陽(yáng)光中捕獲足夠的熱量，在火星上形成液態(tài)水區(qū)域并達(dá)到與地球相近的溫度。他們認(rèn)為，在不久的將來(lái)，就可采用這項(xiàng)技術(shù)建設(shè)人類棲息地。

在一項(xiàng)新的研究中，研究人員表明，在火星表面鋪上薄薄一層半透明氣凝膠，只要幾厘米厚，就能使地表升溫50攝氏度（90華氏度）甚至更高。這足以融化之前封凍在地下的水，提供維持生命必需的要素。

就像二氧化碳等溫室氣體一樣，氣凝膠允許可見(jiàn)光通過(guò)并使地表升溫，但阻礙紅外線逃逸，人類看不見(jiàn)但會(huì)感到熱。憑借其獨(dú)特的結(jié)構(gòu)，氣凝膠產(chǎn)生溫室效應(yīng)的效率可遠(yuǎn)勝二氧化碳。

噴氣推進(jìn)實(shí)驗(yàn)室的研究員勞拉·克貝爾說(shuō)：“液凝膠是一種充滿微小液囊的固體結(jié)構(gòu)。如果把所有液體抽干，并用空氣代替液體，就得到了氣凝膠。”

這些氣囊是加熱火星的關(guān)鍵?？素悹栒f(shuō)：“空氣導(dǎo)熱性極差，但通常可以流動(dòng)，能把熱量帶到各處。而氣凝膠中的空氣被束縛在這些微小的氣囊中，所以無(wú)法相互混合，因而成為極好的隔熱材料?！鳖愃频臍饽z已經(jīng)應(yīng)用到目前正在執(zhí)行火星探索任務(wù)的好奇號(hào)火星車上，此外還可以應(yīng)用到深海管道、消防設(shè)備乃至地球上的房屋。

科學(xué)家可以先小規(guī)模應(yīng)用氣凝膠材料，然后逐步開(kāi)展更宏大的項(xiàng)目。哈佛大學(xué)環(huán)境科學(xué)與工程副教授羅賓·沃茲沃思說(shuō)：“最簡(jiǎn)單的一種……是制作氣凝膠毯，讓來(lái)自地球的藻類和微生物在上面生長(zhǎng)。對(duì)于人類的棲息地——它也照樣保證能工作，但一定要把氣凝膠和其他材料結(jié)合使用?！?/p>

“目前這種形態(tài)的氣凝膠還相當(dāng)脆弱?！笨素悹栒f(shuō)?；鹦谴髿夥浅Ｏ”。覍?duì)大多數(shù)地球生命來(lái)說(shuō)都有毒，所以任何宜居建筑都必須建成密閉的。她解釋道，未來(lái)，可以把氣凝膠夾在結(jié)實(shí)的有機(jī)玻璃中間制成磚瓦，用來(lái)建造供人居住的密封圓頂房屋。

因?yàn)榈厍蛏畹倪@些環(huán)境會(huì)自給自足，它們也會(huì)保護(hù)火星上可能存在的任何生命?？素悹栒f(shuō)：“誰(shuí)也不想登陸火星后，就讓地球生命憑借競(jìng)爭(zhēng)優(yōu)勢(shì)殺死我們發(fā)現(xiàn)的唯一地外生命。這個(gè)解決方案不錯(cuò)，逐步建成基本自足的宜居小島，我們就能住在那里而不至搞得一團(tuán)糟?！?/p>

“還是頭一次，我們認(rèn)為這是一種可能實(shí)現(xiàn)火星宜居的方式，范圍雖小但可以擴(kuò)展。困難是很多，但我們認(rèn)為非常鼓舞人心，因?yàn)樵谖覀冇猩旰芸赡軐?shí)現(xiàn)?！蔽制澪炙颊f(shuō)。

這一發(fā)現(xiàn)雖然令人振奮，但也不過(guò)是在人類已開(kāi)始的一個(gè)故事的最新進(jìn)展踏上月球之前就開(kāi)始了。

維拉諾瓦大學(xué)的天體物理學(xué)和行星科學(xué)教授愛(ài)德華·吉南說(shuō)：“我從小就喜歡的科幻小說(shuō)要變成現(xiàn)實(shí)了。”一個(gè)多世紀(jì)來(lái)，科幻小說(shuō)作者不斷講述人類在這顆紅色星球上定居的故事，將火星描繪為有能呼吸的空氣、液態(tài)水，甚至還有高級(jí)外星生命。

1965年，水手4號(hào)火星探測(cè)器第一次拍攝到特寫照片，發(fā)現(xiàn)火星完全不適宜人類生存——荒涼，干燥，大氣極為稀薄。人類對(duì)火星的認(rèn)識(shí)因此發(fā)生了一次飛躍。

但是作家和科學(xué)家——很多是受到他們喜愛(ài)的小說(shuō)的啟發(fā)——沒(méi)有放棄。不僅如此，他們還專注于地球化：用技術(shù)手段把火星徹底改造成人類能夠生存之地。

1971年，卡爾·薩根建議把火星冰蓋所有水冰和二氧化碳都蒸發(fā)掉。就像導(dǎo)致地球自身全球氣候變暖危機(jī)的溫室效應(yīng)一樣，蒸發(fā)產(chǎn)生的氣體會(huì)引起同樣的效應(yīng)讓火星變暖。但在2018年，美國(guó)國(guó)家航空航天局發(fā)現(xiàn)，如果沒(méi)有非常先進(jìn)的技術(shù)支持，火星上水冰和二氧化碳數(shù)量不足以實(shí)現(xiàn)這個(gè)蒸發(fā)計(jì)劃。

哈佛大學(xué)的沃茲沃思感到形勢(shì)緊迫，要實(shí)事求是地思考地球化的問(wèn)題。他說(shuō)：“我們問(wèn)的是，在我們有生之年而非遙遠(yuǎn)的未來(lái)，什么是切實(shí)可行的，什么又是行不通的?！?/p>

然而，就氣凝膠項(xiàng)目而言，直接的靈感來(lái)自火星本身。

克貝爾說(shuō)，同樣的加熱過(guò)程“目前已在火星上發(fā)生，不過(guò)借助的是固態(tài)二氧化碳（干冰）。它非常透明，在沙丘上積聚。陽(yáng)光穿透干冰，氣體開(kāi)始形成。最后氣體噴發(fā)，產(chǎn)生這些二氧化碳間歇噴泉，留下黑點(diǎn)。這種現(xiàn)象每年春天都會(huì)發(fā)生”。

通過(guò)對(duì)火星地表的研究，克貝爾已經(jīng)發(fā)現(xiàn)了建造人類定居點(diǎn)的理想之地。

她說(shuō)：“我知道火星所有的地下水在哪里。就在那個(gè)名叫亞尼羅桌山群的地方。如果想建人類定居點(diǎn)，這就是我推薦建房的地方;這里的地下水離地表很近?！?/p>

至于火星上那些住在氣凝膠加熱定居點(diǎn)的居民吃什么，吉南和他的天文植物學(xué)學(xué)生正開(kāi)展此項(xiàng)研究。他說(shuō)：“維拉諾瓦大學(xué)有座溫室，我們用模擬的火星土壤栽種植物，光照條件也模擬火星?！?/p>

吉南早就計(jì)劃讓學(xué)生在利用氣凝膠的溫室里開(kāi)展他們建造“火星花園”的實(shí)驗(yàn)。他說(shuō)：“我早買好了氣凝膠，實(shí)際上我們就要做實(shí)驗(yàn)了?！?/p>

吉南已在天體物理學(xué)領(lǐng)域工作了50多年，他希望在有生之年，這項(xiàng)新技術(shù)能見(jiàn)證人類移居火星并在火星上種植糧食。

克貝爾認(rèn)為，解決剩下的挑戰(zhàn)——其中最難的是通往火星的旅程——只是資金的問(wèn)題。她說(shuō)：“要是有人說(shuō)‘錢有的是，放手去做吧，我們就會(huì)去做。人們認(rèn)為這實(shí)在遙不可及，或者只是科幻電影里的東西——其實(shí)不然。我們共同努力吧?！?? ? □

（譯者為“《英語(yǔ)世界》杯”翻譯大賽獲獎(jiǎng)?wù)撸?/p>