为什么美国航空航天局正在探索最深的地球海洋？

Could our understanding of the deep ocean help unlock the mysteries of outer space? Nasa's space mission is leading us to unexplored depths of our own planet.

我们对深海的认识能否帮助我们破解外层空间的谜团？美国国家航空航天局（Nasa）的太空任务引领我们探索地球深处的未知世界。

Our oceans cover more than 70% of the Earth's surface, but over 80% of them remain unexplored. In fact, it is often claimed that we know more about the surface of Mars and the Moon than about the ocean floor on our own planet.

我们的海洋覆盖地球表面的70%，但80%以上的海洋尚未被勘探。事实上，人们常说我们对火星和月球表面的认识超过了地球海底。

Nasa is on a mission to change that. The US space agency is exploring the deep ocean to search for clues of what oceans on other planets could look like, and push the limits of science and technology in one of the most extreme environments on our planet. It is a mission filled with wonder, danger and a not-insignificant risk of implosion.

Nasa开展的任务旨在扭转这一局面。NASA正在探索海洋深处，寻找线索揭示其他星球上的海洋可能是什么样子，在我们这颗星球上最极端的环境中突破科学与技术极限。这项任务充满了奇幻、凶险，以及巨大的内爆风险。

The hope is that the underwater discoveries they make will help to unlock some of the mysteries in outer space while also test some of the equipment and experiments needed for missions elsewhere in the Solar System.

Nasa在海底的发现有助于破解外层空间的某些谜团，同时还能测试在太阳系其他区域开展任务时所需要的某些设备和试验。

Earth's ocean depths are surprisingly similar to some of the conditions Nasa expects to find on other worlds in our Solar System. They could even provide clues about where scientists should be searching for alien life.

地球的深海与Nasa希望在太阳系其他区域寻找的某些环境惊人地相似，甚至为科学家应该去哪里寻找外星生命提供了线索。

The deepest parts of Earth's oceans are known as the hadal zone. Named after Hades, the Greek god of the underworld, it is a forbidding place worthy of its name. Consisting of deep trenches and troughs, it extends 11km (6.8 miles) below the surface of the world's oceans. Cumulatively they account for an area of seabed equivalent to the size of Australia. Yet few vehicles can survive plunging into this dark abyss.

地球海洋最深处称为超深渊带，这是令人生畏的地带，以希腊神话中的冥界之王哈迪斯命名可谓名副其实。超深渊带由很深的海沟和海槽构成，在世界海平面下延绵11公里（6.8英里），占海床的总面积相当于澳大利亚，但几乎任何潜水器坠入这黑暗深渊都是有去无回。

It is here that Nasa scientists, in partnership with the Woods Hole Oceanographic Institute (WHOI) in Massachusetts, are attempting to explore and probe the limits of life on Earth. Even the language the scientists use for their missions to this region shares terms with space exploration – in recent years marine biologists have sent multiple "landers" equipped with sensors and cameras to "crash-land" on the floor of the hadal zone, where they take measurements.

Nasa科学家与马萨诸塞州的伍兹霍尔海洋研究所在这方面展开合作，旨在探索地球生命的极限。科学家在这一地带执行任务中甚至使用太空探索领域的术语：近年来，海洋生物学家已派遣多台装有传感器和摄像头的“着陆器”在超深渊带的海底“强行着陆”，对该地带进行勘测。

But engineers from Nasa's Jet Propulsion Laboratory in Southern California are building a new autonomous underwater vehicle called Orpheus, after the ancient Greek hero who travelled to the underworld and back, to map the more inaccessible depths. Using similar visual navigation technology to Nasa's Perseverance Mars Rover, Orpheus uses highly sensitive cameras to identify rock formations, shells and other features on the ocean floor to build up three-dimensional maps dotted with landmarks (or perhaps seabedmarks). This allows the robot to find its way and recognise places it has already been, but should also help it shed new light on the biodiversity of this harsh environment. "Orpheus is a gateway vehicle," says Tim Shank, a deep-sea biologist who is leading WHOI's hadal exploration programme. "If it works, there is no place in the ocean where you can't go."

然而，位于南加州的Nasa喷气推进实验室的工程师正在制造新型的“俄耳甫斯”自主式水下航行器，命名源于去过冥界又重返人间的古希腊英雄俄耳甫斯，旨在为难以到达的深渊绘制地图。“俄耳甫斯”采用与“毅力号”火星探测车相类似的视觉导航技术，利用高灵敏度摄像头识别岩层、地壳及海床上的其他特征，从而绘制带有陆标（可能应称作海床标）的三维地图。这不仅能使机器人认路，知道自己到了哪里，还有助于我们对这种恶劣环境下的生物多样性有新的认识。“俄耳甫斯是入门潜水器”，深海生物学家蒂姆·尚克说道，他是伍兹霍尔海洋研究所的超深渊带探索项目负责人。“如果行得通，那么海洋里就没有我们去不了的地方”。

It is not the first time that Shank has tried to reach the dark depths of the hadal zone. In 2014, Orpheus' predecessor Nereus was sent down to the Kermadec Trench, which lies north-east of New Zealand. The underwater vehicle imploded some 10km (6.2 miles) down, most likely due to the immense pressure.

这已经不是尚克第一次试图到达超深渊带的黑色深渊了。2014年，“俄耳甫斯”的前辈“涅柔斯”被派遣到位于新西兰西北的克马德克海沟。这艘潜水器在大约10公里（6.2英里）深处发生了内爆，很可能是水压过大造成的。

"After 12 hours, we saw it coming up in small pieces," says Shank, adding that the loss of Nereus made them rethink how they explore the deep sea. About the size of a quad bike and weighing around 550 pounds (250kg), Orpheus is designed to be much lighter, smaller and cheaper than previous underwater vehicles. This should make it nimbler too, allowing it to get into trenches and vents in the sea floor that have never been explored before.

“12小时后，我们在水面发现了残骸”，尚克说道，损失的“涅柔斯”让我们重新思考如何探索深海，他补充道。“俄耳甫斯”大小如同一辆四轮摩托车，约重550磅（250千克），比先前的潜水器设计得更轻、更小、造价更低。这能让它变得更敏捷，可以到达海床上从未探索过的海沟和热液喷口。

Europa on Earth

地球上的欧罗巴

For a long time, marine biologists thought that life in the hadal zone was impossible, but as deep sea submersibles began venturing into the region in the first half of the 20th Century, it became apparent life could survive there. But it was still believed that all living organisms were sustained by a food chain ultimately fueled by photosynthesis. Plants, algae and some marine bacteria in surface waters convert the Sun's energy into sugars which they store in their organic matter. This is then eaten by herbivores, which in turn are eaten by carnivorous animals. Scientists were convinced that organisms on the ocean floor survived off dead organic matter – the carcasses of animals, faeces and the steady fall of other organic detritus or "marine snow" drifting down from above. But it was thought there was not enough food to sustain anything much in the way of sea creatures and the deepest areas were believed to still be too dark and cold for life.

长期以来，海洋生物学家认为，超深渊带不可能存在生命。但20世纪上半叶，随着深海潜水器开始探索该地带，这里是明显存在生命。但人们依旧认为，一切生命体赖以生存的食物链归根结底是由光合作用促成的。表层海水里的植物、海藻、以及部分海洋细菌将太阳能转化成糖，并储存在体内有机物中。它们被食草动物吃掉，食草动物又被食肉动物吃掉。科学家确信海床上的生物是依靠无生命的有机物存活的：动物尸体、粪便、逐渐沉底的有机碎屑（又称“海雪”）从表层漂移到深处。但人们认为这里的食物不足以维持海洋生物的生存，而且最深之处过于黑暗冰冷而不适合生存。

But this perception of the deep ocean changed in 1977, when a US research team dropped a remotely operated vehicle 8,000ft (2,440m) into the Pacific Ocean. The vehicle was dispatched to take images of hydrothermal vents, where heat from volcanic activity seeped from the ocean floor.

但在1977年，美国科考队将一台遥控潜水器投入8000英尺（2440米）深的太平洋中，改变了人们对深海的这种看法。潜水器拍摄了热液喷口的照片，火山活动释放的热量从海底喷涌而出。

To their amazement, the scientists discovered vibrant ecosystems around the vents, teeming with marine organisms, such as translucent snailfish and amphipods, tiny flea-like crustaceans, that had never been seen before.

科学家惊奇的发现，热液喷口的周围存在活跃的生态系统，拥有大量的海洋生物，诸如半透明狮子鱼和片脚生物、像跳蚤一样的甲壳动物，这些都是前所未见的。

"With this discovery, we [came across] a whole new way of living on Earth," says Shank. "These are animals that don't require direct sunlight... they live off chemicals coming out of the sea floor."

“我们发现这是地球上一种全新的生存方式”，尚克说道。“这些动物不需要直射阳光，它们赖以生存的是海底涌出的化学物质”。
原创翻译：龙腾网 https://www.ltaaa.cn 转载请注明出处

The scientists were perplexed: how could species in the hadal zone survive such crushing pressure?

科学家感到困惑的是：超深渊带的生物是如何在毁灭性的水压下存活的？

"The pressure is 15,000 pounds per square inch," says Shank. "It's so intense that the individual cells of an animal would be squeezed out."

“每平方英寸的水压高达15000磅”，尚克说道。“这么高的水压能把动物的单个细胞挤出体外”。

Since that first sighting in 1977, scientists have discovered that organisms living at such depths have adapted on a cellular level to survive down there, says Shank. Creatures in the hadal zone, such as giant amphipod crustaceans and the snailfish, have enzymes called piezolytes (from the Greek "piezin" for pressure), which stop their cellular membranes and proteins from being crushed under extremely high pressure. The piezolytes counteract the pressure by increasing the space that proteins take up inside the organism's cells to counteract the weight of the water around it. "It's like putting the stakes up in a tent," says Shank.

自1977年首次发现以来，科学家发现在这么深的海底，这些生物已经在细胞层面适应了这里的生存环境，尚克说道。超深渊带里的生物，诸如巨大的片脚类甲壳动物和狮子鱼，体内拥有抗压酶piezolyte（源于代表压力的希腊语“piezin”），它能避免细胞膜和蛋白质被超高水压挤碎。抗压酶通过扩大蛋白质在生物细胞内所占的空间来抵消水压，从而抵消周围海水的重量。“就好比把木桩立在帐篷里”，尚克说道。

Discovering organisms that can not only survive, but thrive in such an oppressive environment, raises important questions for biologists looking beyond the realms of our own planet – might it also be found on other ocean worlds.

科学家发现在这样的高压环境下，生物不仅能够生存，而且活得生机勃勃，使探索地外生命的生物学家面临重要问题——在地外海洋世界里是否也能找到生命。

Below the icy surface of Jupiter's moon Europa lies a salt-water ocean that is thought to be between 40 to 100 miles deep (60-150km) and contains twice as much water as all of Earth's oceans combined. Sunlight doesn't penetrate below Europa's thick ice sheet, which is crisscrossed by cracks and fractures. Beneath the icy crust, the pressure is comparable to the hadal zone.

木卫二“欧罗巴”的冰层下面是盐水海洋，深度估计为40-100英里（60-150千米），海水量是地球海水总量的两倍。阳光无法到达“欧罗巴”厚厚的冰层下面，裂缝和断层在冰层上纵横交错，冰壳下面的水压堪比超深渊带。
原创翻译：龙腾网 https://www.ltaaa.cn 转载请注明出处

"Here we have Europa on Earth," says Shank. "I don't see how we could do exploration on Europa, until we did it on Earth."

“我们地球上就有欧罗巴”，尚克说道。“我不知道如何在欧罗巴上探索生命，除非先在地球上做到这一点”。

A robot capable of exploring the Earth's hadal zone could do the same on a frozen moon 628.3 million km (390.4 million miles) away.

如果潜水器能探索地球上的超深渊带，那么它在距离我们6.283亿公里（3.904亿英里）的冰封木卫二“欧罗巴”上也能做到这一点。

"The ocean floor is a great testbed for us to develop the technology that we need in order to have a successful mission to one of these ocean worlds," says Russell Smith, an engineer from Nasa's Jet Propulsion Laboratory, who is part of the team building Orpheus.

“地球海底是我们研发必要技术的绝佳试验场，以便在某个海洋世界中圆满完成探索任务”，Nasa喷气推进实验室的工程师拉塞尔·斯密斯说道，他是制造“俄耳甫斯”潜水器的团队成员。

A robot operating in outer space or the deep ocean, however, must be completely autonomous. "The robot has to be able to make decisions," says Smith, noting that the aim is for Orpheus to be able to detect and classify environmental DNA and chemicals in the water, as well as bring back samples from the ocean floor.

但是，机器人在外层空间或深海行动必须做到完全自主。“机器人必须具备决策能力”，斯密斯说道，目的是让“俄耳甫斯”探测和分类海水中的环境DNA和化学物质，并且将海底样本带回地面。

Building a robot for the hadal zone is incredibly challenging, he says.

制造用于探索超深渊带的机器人极具挑战性，他说道。

Orpheus has to withstand intense pressure and temperature extremes – the water in the hadal zone is just above freezing, but in the hydrothermal vents temperatures can reach 370C (698F).

“俄耳甫斯”必须承受巨大水压和极限温度，超深渊带的水温在零上，但热液喷口的水温可达370C（698F）。

"Developing a vehicle that is going to survive is really hard," says Smith. "You need really thick walls to prevent the electronics from getting crushed or wet." Orpheus is partly constructed from syntactic foam, a buoyant material composed of microscopic glass spheres set in epoxy resin. The foam used in Orpheus comes from leftover material produced for film director James Cameron's Deepsea Challenger, which descended to the bottom of the Mariana Trench, in the western Pacific, in 2012.

“研制出一种能够生存的潜水器确实很难”，斯密斯说道。“你需要非常厚的壳体才能避免电子设备被压坏或受潮”。“俄耳甫斯”部分由空心微珠泡沫塑料制成，这是一种由填充在环氧树脂内的玻璃微珠构成的浮力材料。“俄耳甫斯”使用的泡沫塑料来自为电影导演詹姆斯·卡梅隆制造“深海挑战者号”所剩下的边角料，后者曾在2012年下潜到西太平洋马里亚纳海沟的底部。

As it is pitch black in the deep ocean, Orpheus is equipped with a huge flashlight. If the light stays on the entire time, it will quickly drain the robot's battery, leaving it stranded at the crushing depths. To conserve power, Orpheus will switch to a low-power mode when it isn't taking images or samples, says Smith.

由于深海里漆黑一片，所以“俄耳甫斯”配备了一只巨型手电筒。如果灯光始终开启，会很快耗尽潜水器的蓄电池，使之困在高压的深海里。当“俄耳甫斯”没在拍摄照片或收集样本时，它会为了省电而开启低能耗模式，斯密斯说道。
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Mission to the Moon

登月任务

In 2017, Nasa launched the Systematic Underwater Biogeochemical Science and Exploration Analog, also known as Subsea, to bring together the fields of space and ocean exploration. To date, they have carried out two missions with remotely operated vehicles to hydrothermal vents in the Pacific Ocean.

2017年，Nasa启动了“水下生物地球化学与勘探系统化模拟工程（Subsea）”，旨在将太空与海洋勘探相结合。他们迄今已开展两次任务，利用遥控潜水器探索太平洋里的热液喷口。

The volcanic activity around the Lō`ihi seamount, around 30km (19 miles) off the coast of Hawaii, and Gorda Ridge, 120km (75 miles) off the US coast where California and Oregon meet, is thought to be similar to what may be found in the ocean worlds on Europa and Saturn's moon Enceladus.

科学家认为，木卫二“欧罗巴”和土卫二“恩克拉多斯”的海洋里可能存在类似罗希海底山和戈尔达海岭周围的火山活动，前者距离夏威夷海岸约30公里（19英里），后者距离加州与俄勒冈州的交界海岸线约120公里（75英里）。

"The whole project was predicated on finding areas in our deep ocean that had a really good analogous nature to what is predicted to be active in places like Enceladus," says Darlene Lim, a Nasa geobiologist who is leading the Subsea programme and preparing astronauts for exploration of the Moon and deep space.

科学家推测土卫二“恩克拉多斯”等星球上的火山活动很活跃，整个项目旨在我们的深海中找到与此特征高度相似的区域，Nasa地球生物学家达琳·利姆说道。她正在领导Subsea项目，并为宇航员探索月球和外层空间进行筹备。

Scientists used the two Subsea missions to gain a better understanding of the geology and chemistry of these vents and the life found around them.

科学家利用Subsea工程的两次任务，加深了对热液喷口的地质构造和化学成分及其周边的生物的了解。

"These vents are very innocuous," says Lim. "You have to look very closely for a temperature change in the water coming up through the ground and interacting with very cold seawater. Even that act alone is very valuable for how we might anticipate having to do exploration on some of these ocean worlds in our solar system."

“这些热液喷口是无害的”，利姆说道。“你必须仔细观察从海底喷出的水与冷水交融所引起的温度变化。单是这种变化也很有价值，我们可以预测在太阳系的某些海洋世界中，哪些是有必要探索的区域”。

While sending robots to Europa and Enceladus may still be decades away, Nasa scientists are already applying what they have learned from deep ocean exploration to space missions.

派遣机器人登上“欧罗巴”和“恩克拉多斯”可能是几十年后的事情，但Nasa科学家已将他们从深海学到的经验应用于太空探索任务。

In 2023, Nasa will send a robotic rover to look for water-ice at our Moon's south pole. The mission known as the Volatiles Investigating Polar Exploration Rover, or Viper, will study ice near the lunar crater Nobile in the hope it could be mined as a resource for rocket fuel or drinking water. While not operating underwater, a rover roaming around on the Moon will face many of the same technical challenges.

2023年，Nasa将派遣机器人漫游车去我们月球的南极寻找水冰。这项任务名为“挥发物调查极地探险漫游车（Viper）” ，旨在研究诺毕尔环形山附近的冰，希望将它们开采出来作为火箭燃料或饮用水的来源。虽然不在海底作业，但漫游车在月球上将面临许多相同的的技术挑战。

"We're taking all the learnings from Subsea and applying it to Viper," says Lim, who is also the deputy lead project scientist on Viper.

“我们正在将Subsea工程的一切心得运用到Viper任务中”，利姆说道。她也是Viper的副首席项目科学家。

The aim of the Subsea programme was to ensure that scientists met their research goals in extremely challenging conditions, both from a communications and technology perspective.

Subsea工程旨在确保科学家在极具挑战性的环境下，从通信和技术角度达成科研目标。

From an operations perspective, ocean and space exploration also have a lot in common. In both fields, robots are sent to explore treacherous environments which humans cannot reach, supported by remote teams of scientists. But it could also help prepare astronauts for controlling robotic equipment from a lunar base in the future too.

从作业的角度来看，海洋和太空探索有许多共性。两个领域都需要在远程科学团队的支援下，派遣机器人去探索人类无法到达的危险环境。但也有助于为宇航员做好准备，未来从月球基地上操控机器人设备。

Fewer than 10 scientists went out to sea with the Subsea mission and they worked with a larger group of colleagues on shore. For the Viper mission, a team will operate the rover on Earth in near real-time and will have to analyse data and make decisions very rapidly.

Subsea任务只有不到10名科学家进入海洋，他们与地面的大批同事协同作业。在Viper任务中，一支团队将在地球上实时操控月球漫游车，必须非常迅速地分析数据和做出决策。

Efficient communication is critical during these missions, says Zara Mirmalek, a social scientist with Nasa who helps scientists prepare for exploration in extreme environments, and has worked on both the Subsea and Viper programmes.

高效率通信在这些任务中至关重要，Nasa社会科学家扎拉·米尔马莱克说道。他帮助科学家为探索极端环境做准备，并参与了Subsea和Viper项目。

For deep sea exploration, scientists have to change decisions all the time, depending on the ocean conditions, weather and salinity. "You know that you are going to have less time than you planned for," says Mirmalek. "It's a lot harder to work in the deep ocean because the conditions are so challenging to the technology."

科学家在进行深海探索时，必须根据海况、天气、盐浓度不断改变决策。“要知道你的时间没有预期的那么多”，米尔马莱克说道。“深海里的作业难度更大，因为海况给技术带来的挑战极大”。
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On space missions, communication is extremely limited, says Mirmalek. To prepare for outer space conditions, Mirmalek restricted the Subsea scientists to communicating with each other just once a day. "There were no failures – they met all their research goals," she says.

在太空任务中，通信极其受限，米尔马莱克说道。为了针对外层空间环境做好准备，米尔马莱克限制Subsea项目科学家每天只通信一次。“从未失败过，他们达成了所有的科研目标”，她说道。

"Everything we learned by working together with the oceanographic community has been completely invaluable, really priceless, in helping us have confidence in the process that we're using to design our science operations for Viper," says Lim.

“我们在与海洋学界的合作中学到的一切是真正的无价之宝，帮助我们自信地使用这一流程为Viper任务设计科学作业”，利姆说道。

But much like missions off our planet, those to the bottom of the oceans are also allowing humanity to look at the Earth in new ways. While Nasa says its oceanographic explorations have yelded "thousands" of scientific discoveries, they are also providing information that could be vital if we hope to continue living on a world with healthy oceans. We need to understand our oceanic environments if we are to save them, says Laura Lorenzoni, ocean biology and biogeochemistry program scientist with the science mission directorate at Nasa.

但正如地球以外的任务一样，探索海底能让人类以新的视角看待地球。Nasa声称海洋勘探带来“成千上万”的科学发现，如果我们想继续活在一个拥有健康海洋的世界，海洋勘探提供的信息可能至关重要。我们只有了解海洋环境才能拯救海洋，劳拉·洛伦佐尼说道，她是Nasa科学任务理事会的海洋生物与生物地球化学项目科学家。

"This is critical for life on Earth, and the sustained measurements Nasa has done, and continues to do, are fundamental for ensuring a sustainable use of our ocean resources," she says.

“海洋勘探对于地球上的生命至关重要，Nasa持续不断的的测量是确保我们的海洋资源可持续利用的基础”，她说道。

It means that each step towards the exploration of other worlds, we learn a little bit more about some of the most unexplored parts of our own blue planet too.

这意味着我们在探索其他世界的道路上每迈出一步，也能对自己这颗蓝色星球上某些最未知的区域多一些了解。