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VOA慢速英语2013 EXPLORATIONS - Ancient Martian Conditions Could Have Supported Life

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EXPLORATIONS - Ancient Martian Conditions Could Have Supported Life

From VOA Learning English, this is EXPLORATIONS, in Special English. I’m Kelly Jean Kelly.

And I’m Christopher Cruise. Today we report on recent scientific findings about the planet Mars. We tell about tests of Martian rock gathered by the American space agency’s rover vehicle “Curiosity.” We tell about plans to send another spacecraft and possibly human beings to the red planet. We also explain what scientists have learned from a Martian rock that was found in the Sahara Desert.

The American space agency recently reported that the planet Mars once could have supported micro-organisms, extremely small life forms. The announcement came two weeks ago, after the agency’s Curiosity rover examined a rock on Mars. It was the first sample of rock powder ever collected and tested on the red planet.

Last month, space agency engineers received pictures from the rover, formerly1 called the Mars Science Laboratory. The images showed Curiosity carrying rock particles.

Curiosity used a drill on its two-meter long robotic arms to cut into the rock and collect about ten grams of powder. Space agency officials called the drilling, the biggest success for the Curiosity team since the rover landed on Mars last August.

Joel Hurowitz works for the Jet Propulsion Laboratory in California. He told reporters that the Curiosity team was excited to see that the material was gray, not red -- the color normally linked to the Martian surface.

“It’s pretty exciting to us that you just sort of brush beneath this surface veneer2 and the rocks are a completely different color. So, we’re sort of seeing a new coloration for Mars here, and it’s an exciting one to us.”

The space agency says rocks like these are evidence that Mars could have supported life. 

The color orange is often a sign of oxidized iron. American scientists say oxidation destroys organic material. They say the gray coloring of the powdered rock could mean organic compounds are better-protected.

That is the sound of Curiosity’s test double, cutting a rock here on Earth. The test double is an exact copy of the vehicle on Mars.

Louise Jandura is the sample system chief engineer for Curiosity. She has been working on the project for nearly eight years. She spoke3 to reporters last month. She described the successes of Curiosity as historic -- both for the space program and the United States.

“This is the first time any robot, fixed4 or mobile, has drilled into a rock to collect a sample on Mars. In fact, this is the first time any rover has drilled into a rock to collect a sample anywhere but on Earth.”

Louise Jandura described Curiosity’s drilling equipment as a major step forward.

“It allows us to go beyond the surface layer of the rock, unlocking a kind of ‘time capsule of evidence’ about the state of Mars, going back three or four billion years.”

After the drilling was done and the powder collected, the small laboratory on Curiosity began a series of tests. Then, earlier this month, came the surprising announcement: American scientists said the test results led them to believe there was once life on Mars.

The rock sample came from an area on Mars called Yellowknife Bay. The area had some of the chemicals required to support life as we know it. They include oxygen, hydrogen, nitrogen and carbon.

Scientists believe Mars was once a warmer, wetter environment before turning into a freezing dry desert. Michael Meyer is the lead scientist of the Mars Exploration Program. He spoke at the space agency’s headquarters in Washington.

“This was an ancient environment with the right elements, minerals indicating a near-neutral environment and slightly salty liquid water, all the pre-requisites to support life -- a habitable environment.”

Researchers say the Martian bedrock showed evidence of many periods of wet conditions. And they say there are clay minerals in the rock sample. These minerals are evidence of water.

John Grotzinger is a Curiosity project scientist at the California Institute of Technology.

“Landing there and then almost right off the bat we do find evidence of water and we see an ancient river bed. We’re now finding an environment in the near subsurface, you know not too far beneath the oxidized layer, sort of a neutral rock. All the things that we were really hoping for, to find a place that could have been habitable in its past.”

He also says the water that was once on Mars would have been safe enough to drink.

“We have found a habitable environment that is so benign5 and supportive of life that probably if this water was around and you had been on the planet, you would have been able to drink it.”

It is important not to overstate the discovery. As the Associated Press noted6, “despite the excitement over achieving one of the mission’s main goals, it has yet to find complex organic molecules7 considered the chemical building blocks of life.”

The six-wheeled, nuclear-powered Curiosity has been exploring within a deep, 150-kilometer-wide area called Gale8 Crater9. Now, it will move to a place called Mount Sharp. 

The project is expected to last two years and cost $2.5 billion. Curiosity is not designed to look for microbes that may be alive on Mars today or inspect remains10 of life forms that no longer exist. 

Curiosity is the first Mars rover, but not the only one. The American space agency says it plans to send another rover, called Opportunity, to the red planet in 2020. Opportunity would be part of NASA’s plan to explore the Martian surface and atmosphere. The agency hopes to send humans to Mars in about 20 years.

NASA has announced plans for other projects between now and 2020. They include an orbiter to study the Martian atmosphere and a probe that would take a first look at what lies under the planet’s surface.

NASA’s chief, Charles Bolden, says these projects ensure the United States will be the world leader in exploring Mars. He wants the space agency to take major steps in preparation for sending astronauts to the planet in 20 years.

Curiosity has been studying the atmosphere, making maps of wind and radiation patterns, and measuring changes in air pressure on Mars.

Ashwin Vasavada is the deputy project scientist for the Curiosity mission. He says the mission is mainly concerned about ancient Mars. But he says researchers also want to learn about the planet’s current environment. 

“And it’s a pretty dynamic environment. If you were standing11 next to Curiosity, you’d realize you’re on a planet with an atmosphere -- an atmosphere that is thick enough that when the sun heats the ground every day, gusty12 winds rush up and down the slopes of Gale Crater and Mount Sharp and spawn13 whirlwinds that sweep across the landscape. But the atmosphere isn’t thick enough to shield you from the harsh ultraviolet light and the natural high-energy radiation coming in from space.”

Learning about that radiation is important. So scientists placed a Radiation Assessment14 Detector15, or RAD, on Curiosity. Don Hassler is watching the radiation levels.

“The radiation is a life-limiting factor to habitability, so we need to understand what the radiation is doing if we want to understand the prospects16 for both current, present, and past habitability, but we also need to understand the radiation environment. When we send astronauts to Mars in the future, we need to be able to fully-understand what the radiation is doing so that we can help plan a safe mission for those astronauts.”

He adds that NASA has established a career radiation-dose limit for astronauts.

“I think it’s never really been a question of if we can go to Mars. It’s a matter of when we go, how do we best-protect our astronauts, and so characterizing the radiation environment in terms of the types of radiation that we observe and when it’s the worst and when we’d need to take precautionary measures, I think, is one of the things that we’re, we’re learning from RAD.”

Researchers say Curiosity is providing measurements that will help scientists design a trip by astronauts to Mars. President Obama has challenged NASA to send humans to the red planet by the 2030s. 

Finally, a rock that fell to Earth from Mars has provided surprising new details about the planet. Scientists call the rock -- which weighs 320 grams -- “Black Beauty.” It was discovered two years ago in the Sahara Desert. 

American researchers believe the rock came either from Mars’ crust or surface. They think it was formed more than two billion years ago. That would make it one of the oldest Mars meteorites18 ever found.

The rock contains more water than any of the other 100 meteorites known to have come from the Red Planet. The presence of water increases the possibility that life could have existed on Mars.

The researchers say the rock has given them an idea of ancient surface and environmental conditions on Mars that no other meteorite17 has ever offered.

The rock is composed mainly of two minerals: feldspar and pyroxene. The researchers say this suggests it was sent into space by a volcanic19 explosion. The chemistry is similar to what has been found on Mars by the American space agency’s vehicle “Curiosity” and by orbiting satellites during recent explorations of the Martian surface.


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1 formerly ni3x9     
adv.从前,以前
参考例句:
  • We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
  • This boat was formerly used on the rivers of China.这船从前航行在中国内河里。
2 veneer eLczw     
n.(墙上的)饰面,虚饰
参考例句:
  • For the first time her veneer of politeness began to crack.她温文尔雅的外表第一次露出破绽。
  • The panel had a veneer of gold and ivory.这木板上面镶饰了一层金和象牙。
3 spoke XryyC     
n.(车轮的)辐条;轮辐;破坏某人的计划;阻挠某人的行动 v.讲,谈(speak的过去式);说;演说;从某种观点来说
参考例句:
  • They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
  • The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。
4 fixed JsKzzj     
adj.固定的,不变的,准备好的;(计算机)固定的
参考例句:
  • Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗?
  • Once the aim is fixed,we should not change it arbitrarily.目标一旦确定,我们就不应该随意改变。
5 benign 2t2zw     
adj.善良的,慈祥的;良性的,无危险的
参考例句:
  • The benign weather brought North America a bumper crop.温和的气候给北美带来大丰收。
  • Martha is a benign old lady.玛莎是个仁慈的老妇人。
6 noted 5n4zXc     
adj.著名的,知名的
参考例句:
  • The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
  • Jim is noted for arriving late for work.吉姆上班迟到出了名。
7 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
8 gale Xf3zD     
n.大风,强风,一阵闹声(尤指笑声等)
参考例句:
  • We got our roof blown off in the gale last night.昨夜的大风把我们的房顶给掀掉了。
  • According to the weather forecast,there will be a gale tomorrow.据气象台预报,明天有大风。
9 crater WofzH     
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。
10 remains 1kMzTy     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • The remains of the meal were fed to the dog.残羹剩饭喂狗了。
11 standing 2hCzgo     
n.持续,地位;adj.永久的,不动的,直立的,不流动的
参考例句:
  • After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
  • They're standing out against any change in the law.他们坚决反对对法律做任何修改。
12 gusty B5uyu     
adj.起大风的
参考例句:
  • Weather forecasts predict more hot weather,gusty winds and lightning strikes.天气预报预测高温、大风和雷电天气将继续。
  • Why was Candlestick Park so windy and gusty? 埃德尔斯蒂克公园里为什么会有那么多的强劲阵风?
13 spawn qFUzL     
n.卵,产物,后代,结果;vt.产卵,种菌丝于,产生,造成;vi.产卵,大量生产
参考例句:
  • The fish were madly pushing their way upstream to spawn.鱼群为产卵而疯狂地向上游挤进。
  • These fish will lay spawn in about one month from now.这些鱼大约一个月内会产卵。
14 assessment vO7yu     
n.评价;评估;对财产的估价,被估定的金额
参考例句:
  • This is a very perceptive assessment of the situation.这是一个对该情况的极富洞察力的评价。
  • What is your assessment of the situation?你对时局的看法如何?
15 detector svnxk     
n.发觉者,探测器
参考例句:
  • The detector is housed in a streamlined cylindrical container.探测器安装在流线型圆柱形容器内。
  • Please walk through the metal detector.请走过金属检测器。
16 prospects fkVzpY     
n.希望,前途(恒为复数)
参考例句:
  • There is a mood of pessimism in the company about future job prospects. 公司中有一种对工作前景悲观的情绪。
  • They are less sanguine about the company's long-term prospects. 他们对公司的远景不那么乐观。
17 meteorite 2wNy1     
n.陨石;流星
参考例句:
  • The meteorite in Jilin Exhibition Hall is believed to be the largest in the world.吉林展览馆的陨石被认为是世界上最大的。
  • The famous Murchison meteorite smashed into the Australian ground in 1969.1969年著名的默奇森陨石轰然坠落在澳大利亚。
18 meteorites 12efd1ed528a28fe1f7cb667a7fbc1e0     
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》
19 volcanic BLgzQ     
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。

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