TED演讲：人类为什么要重返火星

 I want to talk about 4.6 billion years of history in 18 minutes. That's 300 million years per minute. Let's start with the first photograph NASA obtained of planet Mars. This is fly-by, Mariner¹ IV. It was taken in 1965. When this picture appeared, that well-known scientific journal, The New York Times, wrote in its editorial, "Mars is uninteresting. It's a dead world. NASA should not spend any time or effort studying Mars anymore." Fortunately, our leaders in Washington at NASA headquarters knew better and we began a very extensive study of the red planet.

One of the key questions in all of science, "Is there life outside of Earth?" I believe that Mars is the most likely target for life outside the Earth. I'm going to show you in a few minutes some amazing measurements that suggest there may be life on Mars. But let me start with a Viking photograph. This is a composite taken by Viking in 1976. Viking was developed and managed at the NASA Langley Research Center. We sent two orbiters and two landers in the summer of 1976. We had four spacecraft, two around Mars, two on the surface -- an amazing accomplishment².

This is the first photograph taken from the surface of any planet. This is a Viking Lander photograph of the surface of Mars. And yes, the red planet is red. Mars is half the size of the Earth, but because two-thirds of the Earth is covered by water, the land area on Mars is comparable to the land area on Earth. So, Mars is a pretty big place even though it's half the size. We have obtained topographic measurements of the surface of Mars. We understand the elevation³ differences.

We know a lot about Mars. Mars has the largest volcano in the solar system, Olympus Mons. Mars has the Grand Canyon⁴ of the solar system, Valles Marineris. Very, very interesting planet. Mars has the largest impact crater⁵ in the solar system, Hellas Basin. This is 2,000 miles across. If you happened to be on Mars when this impactor hit, it was a really bad day on Mars. (Laughter) This is Olympus Mons. This is bigger than the state of Arizona.

Volcanoes are important, because volcanoes produce atmospheres and they produce oceans. We're looking at Valles Marineris, the largest canyon in the solar system, superimposed on a map of the United States, 3,000 miles across. One of the most intriguing⁶ features about Mars, the National Academy of Science says one of the 10 major mysteries of the space age, is why certain areas of Mars are so highly magnetized. We call this crustal magnetism⁷. There are regions on Mars, where, for some reason -- we don't understand why at this point -- the surface is very, very highly magnetized.

Is there water on Mars? The answer is no, there is no liquid water on the surface of Mars today. But there is intriguing evidence that suggests that the early history of Mars there may have been rivers and fast flowing water. Today Mars is very very dry. We believe there's some water in the polar caps, there are polar caps of North Pole and South Pole. Here are some recent images. This is from Spirit and Opportunity. These images that show at one time, there was very fast flowing water on the surface of Mars. Why is water important? Water is important because if you want life you have to have water. Water is the key ingredient in the evolution, the origin of life on a planet.

Here is some picture of Antarctica and a picture of Olympus Mons, very similar features, glaciers⁸. So, this is frozen water. This is ice water on Mars. This is my favorite picture. This was just taken a few weeks ago. It has not been seen publicly. This is European space agency Mars Express, image of a crater on Mars and in the middle of the crater we have liquid water, we have ice. Very intriguing photograph.

We now believe that in the early history of Mars, which is 4.6 billion years ago, 4.6 billion years ago, Mars was very Earth-like. Mars had rivers, Mars had lakes, but more important Mars had planetary-scale oceans. We believe that the oceans were in the northern hemisphere, and this area in blue, which shows a depression of about four miles, was the ancient ocean area on the surface of Mars. Where did the ocean's worth of water on Mars go? Well, we have an idea. This is a measurement we obtained a few years ago from a Mars-orbiting satellite called Odyssey⁹. Sub-surface water on Mars, frozen in the form of ice. And this shows the percent. If it's a blueish color, it means 16 percent by weight. Sixteen percent, by weight, of the interior contains frozen water, or ice. So, there is a lot of water below the surface.

The most intriguing and puzzling measurement, in my opinion, we've obtained of Mars, was released earlier this year in the magazine Science. And what we're looking at is the presence of the gas methane¹⁰, CH4, in the atmosphere of Mars. And you can see there are three distinct regions of methane. Why is methane important? Because on Earth, almost all -- 99.9 percent -- of the methane is produced by living systems, not little green men, but microscopic¹¹ life below the surface or at the surface. We now have evidence that methane is in the atmosphere of Mars, a gas that, on Earth, is biogenic in origin, produced by living systems. These are the three plumes¹²: A, B1, B2.

And this is the terrain¹³ it appears over, and we know from geological studies that these regions are the oldest regions on Mars. In fact, the Earth and Mars are both 4.6 billion years old. The oldest rock on Earth is only 3.6 billion. The reason there is a billion-year gap in our geological understanding is because of plate tectonics, The crust of the Earth has been recycled. We have no geological record prior for the first billion years. That record exists on Mars. And this terrain that we're looking at dates back to 4.6 billion years when Earth and Mars were formed. It was a Tuesday. (Laughter)

This is a map that shows where we've put our spacecraft on the surface of Mars. Here is Viking I, Viking II. This is Opportunity. This is Spirit. This is Mars Pathfinder. This is Phoenix¹⁴, we just put two years ago. Notice all of our rovers and all of our landers have gone to the northern hemisphere. That's because the northern hemisphere is the region of the ancient ocean basin. There aren't many craters¹⁵. And that's because the water protected the basin from being impacted by asteroids¹⁶ and meteorites¹⁷. But look in the southern hemisphere. In the southern hemisphere there are impact craters, there are volcanic¹⁸ craters. Here's Hellas Basin, a very very different place, geologically. Look where the methane is, the methane is in a very rough terrain area.

What is the best way to unravel¹⁹ the mysteries on Mars that exist? We asked this question 10 years ago. We invited 10 of the top Mars scientists to the Langley Research Center for two days. We addressed on the board the major questions that have not been answered. And we spent two days deciding how to best answer this question. And the result of our meeting was a robotic rocket-powered airplane we call ARES. It's an Aerial Regional-scale Environmental Surveyor. There's a model of ARES here. This is a 20-percent scale model.

This airplane was designed at the Langley Research Center. If any place in the world can build an airplane to fly on Mars, it's the Langley Research Center, for almost 100 years a leading center of aeronautics²⁰ in the world. We fly about a mile above the surface. We cover hundreds of miles, and we fly about 450 miles an hour. We can do things that rovers can't do and landers can't do: We can fly above mountains, volcanoes, impact craters; we fly over valleys; we can fly over surface magnetism, the polar caps, subsurface water; and we can search for life on Mars.

But, of equal importance, as we fly through the atmosphere of Mars, we transmit that journey, the first flight of an airplane outside of the Earth, we transmit those images back to Earth. And our goal is to inspire the American public who is paying for this mission through tax dollars. But more important we will inspire the next generation of scientists, technologists, engineers and mathematicians²¹. And that's a critical area of national security and economic vitality²², to make sure we produce the next generation of scientists, engineers, mathematicians and technologists.

This is what ARES looks like as it flies over Mars. We preprogram it. We will fly where the methane is. We will have instruments aboard the plane that will sample, every three minutes, the atmosphere of Mars. We will look for methane as well as other gasses produced by living systems. We will pinpoint²³ where these gases emanate²⁴ from, because we can measure the gradient where it comes from, and there, we can direct the next mission to land right in that area.

How do we transport an airplane to Mars? In two words, very carefully. The problem is we don't fly it to Mars, we put it in a spacecraft and we send it to Mars. The problem is the spacecraft's largest diameter is nine feet; ARES is 21-foot wingspan, 17 feet long. How do we get it to Mars? We fold it, and we transport it in a spacecraft. And we have it in something called an aeroshell. This is how we do it. And we have a little video that describes the sequence.

Video: Seven, six. Green board. Five, four, three, two, one. Main engine start, and liftoff.

Joel Levine: This is a launch from the Kennedy Space Center in Florida. This is the spacecraft taking nine months to get to Mars. It enters the atmosphere of Mars. A lot of heating, frictional heating. It's going 18 thousand miles an hour. A parachute opens up to slow it down. The thermal²⁵ tiles fall off. The airplane is exposed to the atmosphere for the first time. It unfolds. The rocket engine begins.

We believe that in a one-hour flight we can rewrite the textbook on Mars by making high-resolution measurements of the atmosphere, looking for gases of biogenic origin, looking for gases of volcanic origin, studying the surface, studying the magnetism on the surface, which we don't understand, as well as about a dozen other areas.

Practice makes perfect. How do we know we can do it? Because we have tested ARES model, several models in a half a dozen wind tunnels at the NASA Langley Research Center for eight years, under Mars conditions. And, of equal importance is, we test ARES in the Earth's atmosphere, at 100,000 feet, which is comparable to the density²⁶ and pressure of the atmosphere on Mars where we'll fly. Now, 100,000 feet, if you fly cross-country to Los Angeles, you fly 37,000 feet. We do our tests at 100,000 feet.

And I want to show you one of our tests. This is a half-scale model. This is a high-altitude helium balloon. This is over Tilamook, Oregon. We put the folded airplane on the balloon -- it took about three hours to get up there -- and then we released it on command at 103,000 feet, and we deploy²⁷ the airplane and everything works perfectly²⁸. And we've done high-altitude and low-altitude tests, just to perfect this technique.

We're ready to go. I have a scale model here. But we have a full-scale model in storage at the NASA Langley Research Center. We're ready to go. All we need is a check from NASA headquarters (Laughter) to cover the costs. I'm prepared to donate my honorarium²⁹ for today's talk for this mission. There's actually no honorarium for anyone for this thing. This is the ARES team; we have about 150 scientists, engineers; where we're working with Jet Propulsion Laboratory, Goddard Space Flight Center, Ames Research Center and half a dozen major universities and corporations in developing this.

It's a large effort. It's all at NASA Langley Research Center. And let me conclude by saying not too far from here, right down the road in Kittyhawk, North Carolina, a little more than 100 years ago history was made when we had the first powered flight of an airplane on Earth. We are on the verge³⁰ right now to make the first flight of an airplane outside the Earth's atmosphere. We are prepared to fly this on Mars, rewrite the textbook about Mars. If you're interested in more information, we have a website that describes this exciting and intriguing mission, and why we want to do it. Thank you very much. (Applause)

1 mariner   

n.水手号不载人航天探测器，海员，航海者

参考例句：

• A smooth sea never made a skillful mariner.平静的大海决不能造就熟练的水手。
• A mariner must have his eye upon rocks and sands as well as upon the North Star.海员不仅要盯着北极星，还要注意暗礁和险滩。

2 accomplishment   

n.完成，成就，（pl.）造诣，技能

参考例句：

• The series of paintings is quite an accomplishment.这一系列的绘画真是了不起的成就。
• Money will be crucial to the accomplishment of our objectives.要实现我们的目标，钱是至关重要的。

3 elevation   

n.高度；海拔；高地；上升；提高

参考例句：

• The house is at an elevation of 2,000 metres.那幢房子位于海拔两千米的高处。
• His elevation to the position of General Manager was announced yesterday.昨天宣布他晋升总经理职位。

4 canyon   

n.峡谷，溪谷

参考例句：

• The Grand Canyon in the USA is 1900 metres deep.美国的大峡谷1900米深。
• The canyon is famous for producing echoes.这个峡谷以回声而闻名。

5 crater   

n.火山口，弹坑

参考例句：

• With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
• They came to the lip of a dead crater.他们来到了一个死火山口。

6 intriguing   

adj.有趣的；迷人的v.搞阴谋诡计(intrigue的现在分词)；激起…的好奇心

参考例句：

• These discoveries raise intriguing questions. 这些发现带来了非常有趣的问题。
• It all sounds very intriguing. 这些听起来都很有趣。 来自《简明英汉词典》

7 magnetism   

n.磁性，吸引力，磁学

参考例句：

• We know about magnetism by the way magnets act.我们通过磁铁的作用知道磁性是怎么一回事。
• His success showed his magnetism of courage and devotion.他的成功表现了他的胆量和热诚的魅力。

8 glaciers   

冰河，冰川( glacier的名词复数 )

参考例句：

• Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
• It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川，又有雨林和秀丽的山峰。 来自英语晨读30分（高一）

9 odyssey   

n.长途冒险旅行；一连串的冒险

参考例句：

• The march to Travnik was the final stretch of a 16-hour odyssey.去特拉夫尼克的这段路是长达16小时艰险旅行的最后一程。
• His odyssey of passion, friendship,love,and revenge was now finished.他的热情、友谊、爱情和复仇的漫长历程，到此结束了。

10 methane   

n.甲烷，沼气

参考例句：

• The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
• Methane may have extraterrestrial significance.甲烷具有星际意义。

11 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

12 plumes   

羽毛( plume的名词复数 )； 羽毛饰； 羽毛状物； 升上空中的羽状物

参考例句：

• The dancer wore a headdress of pink ostrich plumes. 那位舞蹈演员戴着粉色鸵鸟毛制作的头饰。
• The plumes on her bonnet barely moved as she nodded. 她点点头，那帽子的羽毛在一个劲儿颤动。

13 terrain   

n.地面，地形，地图

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• He knows the terrain of this locality like the back of his hand.他对这一带的地形了如指掌。

14 phoenix   

n.凤凰，长生(不死)鸟；引申为重生

参考例句：

• The airline rose like a phoenix from the ashes.这家航空公司又起死回生了。
• The phoenix worship of China is fetish worship not totem adoration.中国凤崇拜是灵物崇拜而非图腾崇拜。

15 craters   

n.火山口( crater的名词复数 )；弹坑等

参考例句：

• Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
• The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》

16 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

17 meteorites   

n.陨星( meteorite的名词复数 )

参考例句：

• Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
• One theory about the existence of extraterrestrial life rests on the presence of carbon compounds in meteorites. 地球外存在生命的理论是基于陨星上存在碳化合物质这一事实的。 来自《简明英汉词典》

18 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

19 unravel   

v.弄清楚（秘密）；拆开，解开，松开

参考例句：

• He was good with his hands and could unravel a knot or untangle yarn that others wouldn't even attempt.他的手很灵巧，其他人甚至都不敢尝试的一些难解的绳结或缠在一起的纱线，他都能解开。
• This is the attitude that led him to unravel a mystery that long puzzled Chinese historians.正是这种态度使他解决了长期以来使中国历史学家们大惑不解的谜。

20 aeronautics   

n.航空术，航空学

参考例句：

• National Aeronautics and Space undertakings have made great progress.国家的航空航天事业有了很大的发展。
• He devoted every spare moment to aeronautics.他把他所有多余的时间用在航空学上。

21 mathematicians   

数学家( mathematician的名词复数 )

参考例句：

• Do you suppose our mathematicians are unequal to that? 你以为我们的数学家做不到这一点吗？ 来自英汉文学
• Mathematicians can solve problems with two variables. 数学家们可以用两个变数来解决问题。 来自哲学部分

22 vitality   

n.活力，生命力，效力

参考例句：

• He came back from his holiday bursting with vitality and good health.他度假归来之后，身强体壮，充满活力。
• He is an ambitious young man full of enthusiasm and vitality.他是个充满热情与活力的有远大抱负的青年。

23 pinpoint   

vt.准确地确定；用针标出…的精确位置

参考例句：

• It is difficult to pinpoint when water problems of the modern age began.很难准确地指出，现代用水的问题是什么时候出现的。
• I could pinpoint his precise location on a map.我能在地图上指明他的准确位置。

24 emanate   

v.发自，来自，出自

参考例句：

• Waves emanate from the same atom source.波是由同一原子辐射的。
• These chemicals can emanate certain poisonous gases.这些化学药品会散发出某些有毒的气味。

25 thermal   

adj.热的，由热造成的；保暖的

参考例句：

• They will build another thermal power station.他们要另外建一座热能发电站。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

26 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

27 deploy   

v.（军）散开成战斗队形，布置，展开

参考例句：

• The infantry began to deploy at dawn.步兵黎明时开始进入战斗位置。
• The president said he had no intention of deploying ground troops.总统称并不打算部署地面部队。

28 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

29 honorarium   

n.酬金，谢礼

参考例句：

• Travel and hotel costs as well as an honorarium will be provided.我们提供旅费和住宿费以及酬金。
• A group of residents agreed to conduct the survey for a small honorarium.一部分居民同意去进行这样的一个调查，在支付一小点酬金的情况下。

30 verge   

n.边，边缘；v.接近，濒临

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• She was on the verge of bursting into tears.她快要哭出来了。