VOA标准英语2010年-Looking for ET

Scientists target tiny fossils in Martian soil in NASA's search for extraterrestrial life

Rosanne Skirble | Washington, DC 30 April 2010
 A proposed robotic lab would carry instruments for identifying and measuring the chemical building blocks for life (as we know it), including thousands of carbon-carrying compounds, elements such as sulfur¹ and nitrogen, and oxidation states of trace metals associated with life.

They still haven't found any Martian microbes, or telltale signs of alien biospheres orbiting distant stars. But scientists looking for signs of life in our solar system and the universe beyond are not discouraged.

Researchers at the biennial² Astrobiology Science Conference near Houston, Texas, described a series of ambitious new projects they say will continue the search for extraterrestrial life. 

Search for Extraterrestrial Life

Among them was Cornell University researcher Steve Squires³, chief scientist on the Mars Rover Mission for the U.S space agency, NASA. 

In a news briefing he told reporters that astrobiology will be central to future space exploration. "NASA is currently considering 28 different missions. They are sort of breathtaking in their sweep. They cover everything from Mercury landers to fly-bys of objects in the deep outer solar system."

NASA's Opportunity rover used its front hazard-identification camera to obtain this image at the end of a drive on the rover's 1,271st sol, or Martian day (Aug. 21, 2007).

Squires says one of the most ambitious endeavors is a Mars Sample Return Mission, which would retrieve⁴ rocks and soil from the Martian surface in three stages.

A robotic ranger⁵ would collect samples. A lander would pick them up and then rendezvous⁶ with an orbiter to bring them back to Earth.  The project has been on the drawing boards for 20 years, but never acted on. 

But the search for life, Squires suggests, is a long-term effort. "What we're saying is that it is possible to string those out in time, with gaps of potentially years. And what that does is that it makes the overall program more affordable⁷ because it spreads the cost out over time."

Artist rendering⁸ of a Mars Sample Return mission that would use robotic systems and a Mars ascent⁹ rocket to collect and send samples of Martian rocks, soils, and atmosphere to Earth for detailed¹⁰ chemical and physical analysis.

Exploration

Other astrobiology projects in the works include unmanned interplanetary orbiters that would use ice penetrating¹¹ radar¹² to look for a liquid ocean under the icy surface of Jupiter's moon, Europa, and to explore the methane¹³ lakes on Titan, a moon of Saturn¹⁴.

The search for extraterrestrial life actually involves some Earth-centered science, too.

University of California Los Angeles paleobiologist Bill Schopf studies the oldest fossils on earth. He presented new data at the Astrobiology Science Conference that shows diverse micro-fossils found in a layer of gypsum in a 6 million-year-old Mediterranean¹⁵ Sea bed. 

Schopf says orbital mapping also shows similar mineral deposits on Mars. "We now know that this is a good place to look for evidence of fossil life on Mars, but I think that also you might see clumps¹⁶ of organic material and that would be a real good finding on Mars because if we can find the organic matter, then we have a real reason to think that there might once have been life there."

NASA's Mars Exploration Rover Opportunity climbed out of "Victoria Crater¹⁷" following the tracks it had made when it descended¹⁸ into the 800-meter-diameter (half-mile-diameter) bowl nearly a year earlier.

Life on Mars

As luck would have it, the Mars rover, named Opportunity, landed on a field of gypsum - or calcium¹⁹ sulfate six years ago.

NASA's Steve Squires says Mars rocks and soil could yield valuable clues to ancient forms of life. "We know there are iron sulfates, magnesium²⁰ sulfates and calcium sulfates.  Gypsum is a calcium sulfate. All of those are present at the Opportunity landing site."  

UCLA professor Bill Schopf is anxious to analyze²¹ those Martian sulfates for signs of life. "I think that if we had the rocks back tomorrow morning, and I had them in my lab, I think we could solve this problem.

Squires says the discovery of water and organic materials - the building blocks of life as we know it on Earth - will be top priorities on NASA's future deep-space missions.
 

1 sulfur   

n.硫，硫磺（=sulphur）

参考例句：

• Sulfur emissions from steel mills become acid rain.炼钢厂排放出的硫形成了酸雨。
• Burning may produce sulfur oxides.燃烧可能会产生硫氧化物。

2 biennial   

adj.两年一次的

参考例句：

• The workers were strongly against the biennial election.工人们强烈反对两年一次的选举。
• His is a biennial,and one of the most useful pasture plants we have.这是两年生植物，也是我们最有用的牧草之一。

3 squires   

n.地主，乡绅( squire的名词复数 )

参考例句：

• The family history was typical of the Catholic squires of England. 这个家族的历史，在英格兰信天主教的乡绅中是很典型的。 来自辞典例句
• By 1696, with Tory squires and Amsterdam burghers complaining about excessive taxes. 到1696年，托利党的乡绅们和阿姆斯特丹的市民都对苛捐杂税怨声载道。 来自辞典例句

4 retrieve   

vt.重新得到，收回；挽回，补救；检索

参考例句：

• He was determined to retrieve his honor.他决心恢复名誉。
• The men were trying to retrieve weapons left when the army abandoned the island.士兵们正试图找回军队从该岛撤退时留下的武器。

5 ranger   

n.国家公园管理员，护林员；骑兵巡逻队员

参考例句：

• He was the head ranger of the national park.他曾是国家公园的首席看守员。
• He loved working as a ranger.他喜欢做护林人。

6 rendezvous   

n.约会，约会地点，汇合点；vi.汇合，集合；vt.使汇合，使在汇合地点相遇

参考例句：

• She made the rendezvous with only minutes to spare.她还差几分钟时才来赴约。
• I have a rendezvous with Peter at a restaurant on the harbour.我和彼得在海港的一个餐馆有个约会。

7 affordable   

adj.支付得起的，不太昂贵的

参考例句：

• The rent for the four-roomed house is affordable.四居室房屋的房租付得起。
• There are few affordable apartments in big cities.在大城市中没有几所公寓是便宜的。

8 rendering   

n.表现，描写

参考例句：

• She gave a splendid rendering of Beethoven's piano sonata.她精彩地演奏了贝多芬的钢琴奏鸣曲。
• His narrative is a super rendering of dialect speech and idiom.他的叙述是方言和土语最成功的运用。

9 ascent   

n.(声望或地位)提高；上升，升高；登高

参考例句：

• His rapid ascent in the social scale was surprising.他的社会地位提高之迅速令人吃惊。
• Burke pushed the button and the elevator began its slow ascent.伯克按动电钮，电梯开始缓慢上升。

10 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

11 penetrating   

adj.（声音）响亮的，尖锐的adj.（气味）刺激的adj.（思想）敏锐的，有洞察力的

参考例句：

• He had an extraordinarily penetrating gaze. 他的目光有股异乎寻常的洞察力。
• He examined the man with a penetrating gaze. 他以锐利的目光仔细观察了那个人。

12 radar   

n.雷达，无线电探测器

参考例句：

• They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
• Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。

13 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。

14 Saturn   

n.农神，土星

参考例句：

• Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪，为什么只有土星有光环。
• These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。

15 Mediterranean   

adj.地中海的；地中海沿岸的

参考例句：

• The houses are Mediterranean in character.这些房子都属地中海风格。
• Gibraltar is the key to the Mediterranean.直布罗陀是地中海的要冲。

16 clumps   

n.（树、灌木、植物等的）丛、簇( clump的名词复数 )；（土、泥等）团；块；笨重的脚步声v.（树、灌木、植物等的）丛、簇( clump的第三人称单数 )；（土、泥等）团；块；笨重的脚步声

参考例句：

• These plants quickly form dense clumps. 这些植物很快形成了浓密的树丛。 来自《简明英汉词典》
• The bulbs were over. All that remained of them were clumps of brown leaves. 这些鳞茎死了，剩下的只是一丛丛的黃叶子。 来自《简明英汉词典》

17 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。

18 descended   

a.为...后裔的，出身于...的

参考例句：

• A mood of melancholy descended on us. 一种悲伤的情绪袭上我们的心头。
• The path descended the hill in a series of zigzags. 小路呈连续的之字形顺着山坡蜿蜒而下。

19 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。

20 magnesium   

n.镁

参考例句：

• Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
• The water contains high amounts of magnesium.这水含有大量的镁。

21 analyze   

vt.分析，解析 (=analyse)

参考例句：

• We should analyze the cause and effect of this event.我们应该分析这场事变的因果。
• The teacher tried to analyze the cause of our failure.老师设法分析我们失败的原因。