FlyTitle: Astrobiology

A new generation of biology-hunting spacecraft is on its way

探寻地外生物的新一代航天器启程

经济学人双语版-火星生命:继续探寻 Life on Mars: the search continues

AROUND 3.5BN years ago conditions on Earth and Mars were similar. Both had thick atmospheres and liquid water on their surfaces. Both, in other words, had the conditions required to sustain life. And on one of those planets life was, indeed, sustained. Precisely when biology began on Earth remains obscure. But by 3.5bn years ago, a billion years after the solar system formed, it was well established there and has since evolved into the lush abundance of complex forms seen today. Mars, meanwhile, became a freezing desert.

大约35亿年前,地球和火星的状况相似,都有着厚厚的大气层,表面有液态水。换言之,两者都曾具备维持生命所需的条件。而在其中一个星球上,生命确实得以维续下来。生物确切是从何时开始在地球上出现的仍不清楚。但在35亿年前,也就是太阳系形成十亿年后,生命已在地球扎根繁衍,此后不断演化,发展成如今丰富多彩的复杂形态。与此同时,火星却变成了一片冰冷荒漠。

The question nevertheless remains: given that the conditions needed for life to emerge on Earth also seem to have pertained for a time on Mars, might life have evolved there, too? And, if it did, might it still survive in some form, even if only in vanishingly rare amounts?

一个问题挥之不去:既然火星似乎也有一段时间具备地球上那种维系生命的条件,那里说不定也有生命进化发展?如果是这样,这些生命体会不会仍以某种形式存活着,即便可能数量稀少到难以察觉?

To answer that question means visiting the place—if not with people then at least with robots. And now is a good time to do so, for Earth and Mars are aligned in a way that means the journey takes less than seven months. On July 20th, therefore, the first of a caravan of craft planning to take advantage of this alignment set off. That was when Al Amal, meaning “hope”, rose from Japan’s spaceport on Tanegashima, off the southern tip of Kyushu. Al Amal is an orbiter intended to study Mars’s weather, and also look at how the Martian atmosphere is leaking into space. Its lift-off adds the United Arab Emirates (UAE) to the list of countries that have dispatched probes towards extraterrestrial bodies.

要回答这个问题,就要访问这颗星球——如果不是人类亲自来,至少得是机器人。而现在正是一个好时机,因为眼下地球与火星间的距离最短,使得探访的旅程只需七个月不到。一批航天器计划利用这一个“窗口期”探索火星。其中,阿联酋的“希望号”(Al-Amal)火星探测器率先在7月20日启航,从位于日本九州南端的种子岛航天中心发射升空。“希望号”是一枚轨道探测器,计划研究火星的天气以及火星大气层如何逸散至太空。它的发射令阿联酋跻身向地外天体发射过探测器的国家之列。

Al Amal was followed, on July 23rd, by Tianwen-1 (“heavenly questions”), a Chinese mission consisting of an orbiter, a lander and a rover that took off from Wenchang Space Launch Centre, on Hainan. The lander’s provisional target is Utopia Planitia, a large impact basin where an American craft, Viking 2, touched down in 1976. Chinese officials have so far declined to release much detail about Tianwen-1’s scientific aims, but what is known of them suggests that it will study the distribution of ice on Mars and examine how the planet’s habitability has changed over time.

继“希望号”之后,中国的火星探测器“天问一号”(包含轨道器、着陆器、火星车)于7月23日在海南文昌航天发射中心升空。其拟定着陆点是火星上的乌托邦平原(Utopia Planitia),1976年美国的“海盗2号”探测器也是在这片大型撞击盆地上着陆。目前为止,中国官员还不肯就“天问一号”的科研目标透露太多细节,但据悉它将研究火星上冰的分布以及火星宜居性的演变过程。

Lack of publicity has not been an issue for the third member of the flotilla. On July 30th NASA, America’s space agency, launched Perseverance, a one-tonne, six-wheeled rover, from the country’s principal spaceport at Cape Canaveral, in Florida. It cost $2.4bn to build and dispatch, and will absorb another $300m in operating costs during its mission. It is the most sophisticated vehicle sent by America to the Martian surface.

这批星际舰队的第三位成员则一点也不低调。美国国家航空航天局(以下简称NASA)7月30日在佛罗里达州的卡纳维拉尔角(Cape Canaveral,美国主要的航天中心)发射了一吨重的 “毅力号”(Perseverance)六轮火星车。其建造和发射成本达24亿美元,在执行任务期间还要另外耗费三亿美元的运营成本。这是美国迄今送往火星表面的最先进的探测器。

Once upon a time…

很久以前……

Perseverance is aimed at a 45km-wide crater called Jezero that was, 3.5bn years ago, home to a lake. The rover’s main goal is to look for signs of ancient life. But it is also the opening gambit in a decade-long plan to bring Martian rocks to Earth. Jezero itself sits on the inner rim of Isidis Planitia, another large impact basin, which was excavated 3.9bn years ago. One source of the water which formed the lake that once lay within it seems to have been a river leading to a well-preserved delta. The layers of sediment in this feature (colour-coded in the picture above according to their mineral composition) are prime targets in the search for Martian biology.

“毅力号”的目标着陆点是一个名为杰泽罗(Jezero)的45公里宽的陨石坑,35亿年前那里曾有一个湖泊。这台火星车的主要使命是寻找远古生命的痕迹。但它同时也是一个把火星岩石带回地球的十年计划的先头部队。杰泽罗位于另一个大型撞击盆地伊希地平原(Isidis Planitia,形成于39亿年前)的内缘。它里面曾存在过的湖泊似乎有一部分水源来自一条河流,而这条河流形成了一片保存完好的三角洲。该地的沉积层(上图中按所含矿物成分以不同颜色标记)正是探寻火星生物的主要目标。

On Earth, some of the oldest evidence for life comes in the form of stromatolites. These stratified structures form in shallow water when colonies of microbes grow layer upon layer, trapping sediment as they do so. The most ancient examples are thought to be those found in Greenland in 2016, which have been dated to 3.7bn years before the present day. If there was sufficient time for stromatolite-forming organisms to evolve on Earth by this date then there is no obvious reason why they might not also have evolved on Mars.

在地球上,一些最古老的生命证据蕴含在叠层石中。微生物群落在层层叠生时将海水中的成分粘结成沉积物,在浅水中就逐渐形成了这些分层结构。2016年在格陵兰发现的叠层石被认为是最古老的样本,有37亿年的历史。既然形成叠层石的生物在此前有足够的时间在地球上进化,那么没有明显的理由认为它们不曾在火星上进化过。

Spotting stromatolite-like layers in rocks will not, though, be enough on its own. Researchers will also need to consider the textures of the rocks concerned and the distribution within them of potentially telltale minerals and organic molecules. Confusingly, in chemistry-speak, an organic molecule is not necessarily of biological origin. The term just means that it is built around carbon atoms, so organic molecules can also originate inorganically, as it were. The biological nature of an organic molecule has thus to be justified by other evidence. As Kathryn Stack Morgan, a geologist who is the Perseverance mission’s deputy project scientist, observes, “This is exactly the type of thing that we do here on Earth to make a case for biosignatures in our own rock record, and for the very first time using our instruments we can do that on the surface of Mars.”

但是,在岩石中发现叠层石之类的结构本身并不够。研究人员还要考虑岩石的质地和可能显示生命痕迹的矿物和有机分子在其中的分布。这里会造成混淆的是,化学上所说的有机分子不一定来自生命体。这个名词只意味着分子是围绕碳原子构成,因此“有机分子”在某种程度上也可能是无机形成的。所以有机分子的生物属性必须有其他证据来辅助推定。正如“毅力号”项目的副项目科学家、地质学家凯瑟琳·斯塔克·摩根(Kathryn Stack Morgan)所说:“在地球上我们也在做同样的事情,验证岩石记录中的生物印记。而现在我们可以破天荒地运用仪器在火星表面做这种研究了。”

Rocks and hard places

艰险之地

Perseverance carries two instruments in particular that are intended to examine the surfaces of rocks which the rover encounters. Both will look for pertinent minerals and organic molecules. SHERLOC, situated at the end of the rover’s robotic arm, will shine a laser onto tiny grains in rocks it comes across. By analysing the spectrum of the light that is scattered back, this instrument will be able to identify molecules in the grains under scrutiny. WATSON, a camera, will then take close-ups of rocks that SHERLOC deems worthy of further study.

“毅力号”专门搭载了两台仪器,用于检测火星车走过的岩石表面,寻找包含生物印记的矿物质和有机分子。在火星车机械臂的末端装配了拉曼光谱仪“SHERLOC”,它能发射激光到途经的细小岩石颗粒上。通过分析散射回来的光线光谱,该仪器能识别所探测岩石颗粒内的分子。而名为“WATSON”的照相机会对SHERLOC认为值得进一步研究的岩石拍摄特写照片。

Mapping SHERLOC’s chemical analyses onto WATSON’s high-resolution images will show how different mineral layers are arranged and textured. That will be a big improvement over the instruments on board NASA’s current operational Mars rover, Curiosity, which arrived in 2012. These are capable only of grinding up rocks to work out whether or not organic molecules are present in the bulk material. If there are stromatolites (or even fossils of more complex creatures) Perseverance will be able to see them, both chemically and optically.

把SHERLOC的化学分析与WATSON拍摄的高分辨率图像对应起来,将显示出不同矿物层的铺排和结构。相比NASA目前运行的火星探测器“好奇号”(于2012年抵达火星)上的仪器,这是一项重大的改进。“好奇号”的仪器只能磨碎石块,从整体上分析其中是否存在有机分子。如果遇到叠层石(甚至更复杂生物的化石),“毅力号”将能通过化学分析和光学观测两种途径看到它们。

As did Curiosity, Perseverance will rely on an autopilot to guide it through the atmosphere to the planet’s surface, after arriving at a velocity, relative to its target, of 19,500km per hour. “We refer to it as the seven minutes of terror,” says Matt Wallace, an engineer who is the mission’s deputy project manager. The rover’s autonomy will then carry over to its everyday operations. Because of the time it takes radio waves to travel from Earth to Mars, Perseverance will receive instructions only once a day. On the ground on Mars it will need to find and avoid awkwardly placed rocks, and also more serious hazards, such as cliffs, by processing, in real time, pictures coming from its 23 cameras. This autonomy, NASA is confident, will permit the new rover to cross the Martian surface routinely and safely at a speed of around 150 metres per hour, double that at which Curiosity is usually allowed to travel.

与“好奇号”一样,“毅力号”在抵达后将由自动驾驶仪引导穿越火星大气层,着陆火星表面。它抵达火星大气层顶部时相对于火星的速度将达到每小时19,500公里。该任务的副项目经理、工程师马特·华莱士(Matt Wallace)表示:“我们称之为‘恐怖七分钟’。”然后,火星车将自主执行日常任务。由于无线电波从地球传到火星需要一定时间,“毅力号”每天只会接收一次指令。在火星表面,它需要通过实时处理自身配备的23个摄像头拍摄的图像,发现并避开杂乱的岩石以及悬崖等更大的危险。NASA相信,这种自主性将让这台新火星车以每小时约150米的速度在火星表面来回安全行驶,是“好奇号”正常安全行驶速度的两倍。

As well as eyes, Perseverance has ears. A pair of microphones on board will permit people to hear the winds of Mars for the first time. They will also be able listen to the whirr of the rover’s gears, the crunch of its wheels as it moves across the regolith (the crushed rock that passes for soil on Mars) and the percussive sounds of the drill at the end of its arm as it chips out samples of rocks to study.

“毅力号”不但有“眼睛”,还有“耳朵”。它携带的两个麦克风能让地球人第一次听到火星上的风声。人们还将听到火星车齿轮转动的嗡嗡声、车轮碾压风化层(可以算是火星土壤的碎石)的嘎吱声,以及机械臂末端的钻头钻凿岩石样本时的敲击声。

经济学人双语版-火星生命:继续探寻 Life on Mars: the search continues

Not all of those samples will be discarded after investigation. Some will be packed for eventual dispatch to Earth by a project called the Mars Sample Return mission. This is a collaboration between NASA and the European Space Agency, ESA, that involves launching five separate spacecraft over the course of a decade. Perseverance is the first, and its collaboration-related job is to seal samples of Martian rock that its operators think worthy of further investigation into one of around 30 titanium tubes which it carries. As the illustration overleaf presages, it will leave these on the surface to be picked up by an ESA-designed “fetch rover” that could arrive as early as 2028. Once collected, the tubes will be brought back to Earth by a system of relay craft, and their contents analysed.

这些样品在探测后不会被全部丢弃。其中一些会被打包,通过名为“火星样本返回”(Mars Sample Return)的任务最终发回地球。这是NASA与欧洲航天局(ESA)的合作项目,计划在十年内分别发射五枚航天器到火星。“毅力号”是第一个,它与这个项目有关的任务是把它的操作人员认为值得进一步研究的火星岩石样本分别封装至它携带的约30根钛管中。如下图所演示,这些金属管将被留在火星表面,而由欧洲航天局设计的“取样火星车”最快可在2028年抵达火星拾取它们,再通过航天器接力带回地球,以分析其中的样本。

Perhaps most intriguingly of all, Perseverance also carries a 1.8kg helicopter, called Ingenuity. If this manages to fly in Mars’s thin atmosphere (which has about 1% of the density of Earth’s at the surface), it will represent the first controlled flight, beyond the landing and lift-off of a spacecraft, to take place on another heavenly body. And if that happens, it will pave the way for more sophisticated drones on future missions to act as scouts.

也许最有趣的是,“毅力号”还搭载了一台重1.8公斤、名为“机智号”(Ingenuity)的无人机。假如它能在火星稀薄的大气层(表面大气密度约为地球的1%)中飞行,那将是另一天体上除了航天器着陆和升空以外的首次受控飞行。如果真能实现,那将为在以后的火星任务中运用更先进的无人机展开探测开辟道路。

Every contact leaves a trace

触物留痕

The life-seeking instruments on Perseverance are more advanced than anything that has come before them, but this was not the original plan for the next phase, after Curiosity, of NASA’s attempt to find life on Mars. In February 2012, while Curiosity was still making its way there, Barack Obama’s administration slashed NASA’s planet-exploration budget by a fifth. At the time, American scientists had been developing a programme called ExoMars, in collaboration with ESA. This was to involve an orbiter and several rovers being launched from 2016 onwards, with a combination of tools intended to look for signs of life.

“毅力号”上的生命探测仪器比之前的探测设备都更先进,但这并非NASA的火星生命探测行动原本计划在“好奇号”之后展开的下一阶段。2012年2月,“好奇号”仍在飞往火星的途中,奥巴马政府把NASA的行星探索预算削减了五分之一。当时,美国科学家一直在跟欧洲航天局合作开发一个名为ExoMars的项目,计划从2016年起发射一枚轨道飞行器及多台火星车,搭载一系列工具寻找地外生命的痕迹。

Mr Obama’s cuts killed American involvement in ExoMars and, by the time Curiosity reached Mars in August 2012, NASA had no plans to send any future rovers. The overwhelmingly positive public reaction to Curiosity’s nail-biting landing, however, helped persuade the agency’s chiefs to reconsider their priorities and put together a scaled-back version of previous plans that required no increase in the budget. The result, the mission now known as Perseverance, was announced a few months later.

预算被削减导致美国退出了ExoMars项目, 到“好奇号”于2012年8月抵达火星时,NASA已经没有计划再发射任何火星车。但民众对“好奇号”扣人心弦的着陆反应极为热烈,促使NASA的主管们重新思考各项工作的轻重缓急,在之前的基础上整理出了一个缩减版的、无需增拨预算的火星探测计划。结果就是,NASA在数月后宣布了如今大家所知的“毅力号”计划。

Meanwhile, ESA had kept its part of the ExoMars programme alive, turning to Russia for help with launching and hardware. In 2016 the agency delivered the first part of the programme, the Trace Gas Orbiter. Its goal is to measure the precise concentrations in Mars’s atmosphere of substances, including methane, water vapour, nitrogen oxides and acetylene, that each form less than 1% of the atmosphere’s total volume but which might be signs of biology.

与此同时,欧洲航天局继续推进自己在ExoMars项目中的那部分,同时转向俄罗斯寻求发射和硬件方面的协助。2016年,欧洲航天局交付了该项目的第一个组件——微量气体轨道器(Trace Gas Orbiter)。其目标是测量火星大气层中的甲烷、水蒸气、氮氧化物和乙炔等物质的精确浓度,虽然这些物质各占火星大气层总量的不到1%,但可能是生物存在的信号。

Methane is of particular interest since its presence varies with both time and location on the planet’s surface. Methane does not live long in the Martian atmosphere, suggesting there is an active source of the gas. On Earth, living things emit methane as they digest nutrients. But purely geological processes can also liberate the stuff.

甲烷尤其受关注,因为它在火星表面的浓度随时间和位置而变化。甲烷不能在火星大气层中长期存在,这表明火星上有活跃的甲烷来源。在地球上,生物在消化营养物时会释放甲烷。但纯粹的地质过程也会释放这种物质。

经济学人双语版-火星生命:继续探寻 Life on Mars: the search continues

The next step in ESA’s ExoMars programme is a rover, called Rosalind Franklin. This was also scheduled for launch in the current window. However, a combination of technical delays and the effect of covid-19, which has meant the team of engineers involved could not easily travel to complete the manufacture and testing of the rover, has pushed the lift-off date back to the next favourable alignment, in 2022.

欧洲航天局ExoMars项目的下一步是发射名为“罗莎琳德·富兰克林号”(Rosalind Franklin)的火星车。原计划在当前这个窗口期发射。但由于技术延误,再加上新冠疫情妨碍了工程师团队出差完成它的制造和测试工作,发射日期推迟至将于2022年出现的下一个火星探测窗口期。

When Rosalind Franklin eventually does arrive on Mars (2023, if this timetable is adhered to), the craft will crawl over an area called Oxia Planum. This has clays that date back around 4bn years, which will make it the oldest site yet explored on Mars. Since clay minerals require water to form, there are high hopes that Oxia Planum may once have been a life-friendly region.

到“罗莎琳德·富兰克林号”最终抵达火星时(一切如期推进的话将是在2023年),它将在一处名为奥克夏平原(Oxia Planum)的区域行驶。这里的粘土有40亿年的历史,将是人类探索的最古老的火星区域。由于粘土矿物要有水才能形成,奥克夏平原很可能曾经具备生命存在的条件。

Rosalind Franklin’s scientific payload will be capable of much more sophisticated analyses than Perseverance’s. In particular, the Mars Organic Molecule Analyser (MOMA) will be able to extract organic molecules from rocks and regolith more effectively than before.

“罗莎琳德·富兰克林号”搭载的科学仪器所能开展的分析要比“毅力号”复杂得多。尤其是其中的“火星有机分子分析仪”(以下简称MOMA)能比以往更有效地从岩石和风化层中提取有机分子。

Previous attempts to study organic molecules on Mars have been plagued by the presence of chemicals called perchlorates. These were first seen in 2008, by NASA’s Phoenix lander, and were confirmed by Curiosity half a decade later. Those missions baked their Martian samples in ovens, to release the organics. That also released chlorine and oxygen from the perchlorates, and these oxidised most of the organic molecules present. MOMA will circumvent this problem by using an ultraviolet laser that will knock organic molecules off rock samples so fast that any perchlorates present will not have time to decompose.

过去,对火星上有机分子的研究一直备受高氯酸盐这种化学物质的干扰。NASA的“凤凰号”着陆器在2008年首次发现了这些物质,五年后“好奇号”也印证了其存在。两次航天任务都用烤箱烘烤火星样品来释放有机物,但这也让其中的高氯酸盐释出了氯和氧,令样品所含的有机分子大部分都被氧化。而MOMA将利用紫外线激光让岩石样品释放有机分子,速度之快将令样品中所含有的任何高氯酸盐都来不及分解,从而避免了这个问题。

Rosalind Franklin’s most important tool, however, will be a drill that can collect samples from two metres below the surface. This is crucial for recovering material in which organic molecules can be found in a good state of preservation. The thin Martian atmosphere is easily penetrated by ionising radiation from space. This slams into the surface and even travels a little way beneath it. As Jorge Vago, ExoMars’s lead scientist, observes, “Over many millions of years, this ionising radiation acts like gazillion little knives slowly cutting away the functional groups of the organic molecules you would like to hopefully discover.” Use a drill to go deep enough, though, and material it collects will have been protected from radiation by several metres of rock. ESA’s modelling suggests that samples from 1.5 metres down would be scientifically interesting. The deepest any mission has so far sampled under the surface of Mars is a few centimetres.

不过“罗莎琳德·富兰克林号”最重要的工具是可以从地下两米深处钻取样品的钻头。这对获取含有保存良好的有机分子的样本至关重要。来自太空的电离辐射很容易穿透火星稀薄的大气层,冲击火星表面,甚至再往地下穿透一点。正如ExoMars的首席科学家豪尔赫·巴戈(Jorge Vago)所言,“经过千百万年,这种电离辐射就像是无数把小刀慢慢凿掉了人们希望找到的有机分子的官能团。” 但如果用钻头探入足够深的地方,收集到的样本就有几米厚的岩层保护,不受辐射的影响。欧洲航天局的模型运算表明,从1.5米以下收集样本在科研上会很有意义。迄今为止,火星探测任务的采样最深也不过是到表面以下几厘米。

The jackpot of this treasure hunt would be to find things like sugars, phospholipids (constituents of the membranes of cells), nucleotides (the “letters” of genetic material) or amino acids (the building blocks of proteins) that are characteristic of life on Earth. But consolation prizes might be available in the form of less direct signals of biology within the chemistry—traces of the actions of enzymes, for example. As Dr Vago observes, the way fatty acids are synthesised biologically on Earth means that they usually have an even number of carbon atoms, although there is nothing in their underlying chemistry which favours that in abiotic syntheses. Finding a pattern like this, or something equally chemically striking, in Martian organic molecules would be encouraging to those who hope that Mars has or once had life.

火星寻宝之旅的“头奖”会是发现糖类、磷脂(细胞膜的成分)、核苷酸(遗传物质的“字母”)或氨基酸(蛋白质的基本单位)等标志着地球生命的物质。而“安慰奖”则可能是从化学反应中找到一些间接的生物信号,例如酶作用的痕迹。正如巴戈所观察到的,在地球上,脂肪酸的生物合成方式意味着它们通常含有偶数个碳原子,但在非生物合成脂肪酸的基本化学过程中并没有这种倾向。如果能在火星有机分子中找到类似的模式或同样瞩目的化学发现,将令希望火星存在或存在过生命的人们振奋鼓舞。

Many hands

众人拾柴

The UAE’s launch of Al Amal shows how even a small country can join the space race if it is determined enough. No one, however, expects it to become a serious space power. China, though, with half a dozen visits to the Moon under its belt, already is one. Nor is Tianwen-1 the first Chinese attempt to join the Mars club. In 2011 a craft called Yinghuo-1 (“firefly”) attempted to hitch a ride with Phobos-Grunt, a Russian probe. Unfortunately, the rocket intended to propel the combined mission on its way malfunctioned, and it never left Earth orbit. This time, China is going it alone.

阿联酋发射“希望号”表明,只要下定决心,小国也能加入太空竞赛。不过也没人预期它会成为真正的太空强国。而已六次探月的中国原本就已经是太空强国了。“天问一号”也不是中国加入火星探测俱乐部的首次尝试。2011年中国的“萤火一号”探测器曾计划跟随俄罗斯的“福布斯-土壤”(Phobos-Grunt)探测器探测火星。不幸的是,这一联合项目的火箭在发射中出现故障,“萤火一号”根本没能离开地球轨道。这一次,中国自己来了。

One thing which is known is that the mission will host around a dozen scientific instruments, including cameras, chemistry sets, magnetometers and radars. Officials from the China National Space Administration say the plan is to make detailed surveys of the surface. A ground-penetrating radar, for example, will measure the thickness and composition of layers within the regolith and identify any ice within 100 metres of the surface.

目前已知的一点是“天问一号”搭载有摄像头、化学仪器、磁力计、雷达等大概12台科学仪器。中国国家航天局的官员表示,其目标是详尽勘测火星表面。例如,探地雷达将测量火星风化层的各层厚度和构成,查找火星表面以下100米内的冰层。

It will be a sophisticated spacecraft, if details revealed about the landing system are accurate. Zhang Rongqiao, the chief designer, told Chinese television-viewers in 2019 that the lander would separate from the craft’s main body at an altitude of 70 metres and hover until it found a safe landing spot. Cameras and laser scanners will help this lander avoid obstacles as it makes its way to the surface.

如果已披露的有关着陆系统的细节信息正确无误,那“天问一号”会是一台先进的航天器。总设计师张荣桥在2019年对中国的电视观众表示,着陆器将在70米的高度与航天器的主体分离并悬停,直至找到安全着陆点。摄像头和激光扫描仪将辅助着陆器在降落过程中避开障碍物。

Tianwen-1’s lander does not look capable, from its instrument list, of quite the sorts of sophisticated biology-detecting activity planned for Perseverance and, after it, Rosalind Franklin. But even if that is the case, those other two vehicles, combined with the forthcoming ESA and NASA Mars sample-return mission, do now offer a realistic possibility of answering the question of whether there is, or was, life anywhere other than on Earth. A failure to find it would be a disappointment, although the search would no doubt go on, both on Mars and elsewhere. But an answer in the affirmative, even were that life only bacterial and extinct, would surely transform humanity’s view of itself as profoundly as did the discoveries of Nicolaus Copernicus and Charles Darwin.■

从所搭载的仪器来看,“天问一号”的着陆器似乎不能开展“毅力号”和之后的“罗莎琳德·富兰克林号”计划开展的那种复杂的生物探测活动。但即便如此,就凭这后两者再加上欧洲航天局和NASA即将启动的火星样本返回任务,对于火星上是否存在或曾经存在生命的问题,答案已不再遥不可及 。如果最终没能找到生命迹象,人们会感到失望。但毫无疑问,无论是在火星还是其他地方,探索还会继续。但如果找到了,哪怕只是已经灭绝的细菌类生物,也势必会像哥白尼和达尔文当年的发现那样,深刻改变人类对自身的看法。