NASA Focuses on Earth-Like Planets
For decades, looking for life elsewhere in the universe meant listening for signals that could be from distant civilizations. But recent breakthroughs in space technology refocused some of that effort toward finding planets that may harbor life, even in its primitive form.
When NASA launched the Kepler Space Telescope in 2009, scientists learned something new - and quite significant, says the director of the Space Telescope Science Institute, Matt Mountain.
“Our galaxy has at least 100 billion planets in it. And we didn't know that five years ago, said Mountain.
Of course, Kepler and today's other powerful telescopes cannot actually see those planets; they are too faint against the light of their stars.
But scientists can measure the change of light when they pass in front of the star and analyze the light passing through their atmosphere to determine what is in it.
“Well, if we were looking at Earth, we would see signs of our sky, our blue sky, we would see signs of oxygen, of carbon-dioxide, of sulfur dioxide from volcanoes and we might even see signatures that there was plant life, said NASA's astrophysicist and former astronaut John Grunsfeld. And we see that by dissecting the light into its component colors.
Most of the planets discovered so far are unlike Earth. They are too big, too small, too close to their sun, or too far away to support life. But astrophysicist Sara Seager says small planets the size of Earth are extremely common.
“We're looking for biological signatures, gasses that are produced by life, gasses that don't belong in the atmosphere, said Seager.
In cooperation with the European Space Agency and scientists from other nations, NASA is building the next generation of space telescopes that may be able to find evidence of life.
The James Webb Space Telescope, scheduled to be deployed in 2018, will have unprecedented sensitivity and resolution that will greatly improve the spectroscopic analysis of distant stars and planets.
NASA’s chief scientist Ellen Stofan says the agency also plans to look for life on Jupiter’s moon Europa, which may have an ocean under its ice cover.
“In our own solar system we know where to go, we know what to measure it and we're in the process of doing just that. Looking out, beyond our solar system, we're on the right track, we're making the right measurements and we're just on the cusp of learning so much, said Stofan.
Scientists say there's a very high probability that they will find a planet very much like Earth. That could help answer the question: how hard is it for life to get a foothold in the universe?
词语分析
budget
困难程度：4星核心词语，属常用3000词
英汉讲解
n.预算
vt.编预算；为 ... 做预算
vi.节省开支
adj.便宜的；不贵的
参考例句
用作名词
Congress has approved the new educational budget.
国会通过了新的教育预算。
用作及物动词
The government has budgeted 10000000 pounds for education spending.
政府将10000000英镑编入教育预算。
用作不及物动词
If we budget carefully, we'll be able to afford a new house.
假如大家精打细算就能买一座新房屋了。
用作形容词
You can buy high-quality goods at budget prices there.
你可以在那买到物美价廉的产品。
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contain
困难程度：5星基本词语，属常用1000词
英汉讲解
vt.容纳；包括；抑制；克制
vi.自制
参考例句
用作及物动词
The atlas contains forty maps.
这个地图集有四十幅地图。
用作不及物动词
She couldn't contain herself for joy.
她开心地很难自制。
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expert
困难程度：4星核心词语，属常用3000词
英汉讲解
n.专家；能手
adj.熟练的；内行的
参考例句
用作名词
She is a reputable expert.
她是个有声望的专家。
用作形容词
The surgeon cut away the tumour with expert skill.
外科医生用熟练的技术把肿瘤切去。
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virus
困难程度：4星核心词语，属常用3000词
英汉讲解
n.病毒；病原体
参考例句
用作名词
Scientists have isolated the virus causing the epidemic.
科学家们已离别出引起这种时尚病的病毒。
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funeral
困难程度：3星常用词语，属常用6000词
英汉讲解
adj.葬礼
n.葬礼
参考例句
用作形容词
Their cars headed the funeral procession.
他们的车队在葬礼队伍的最前面。
用作名词
They held a state funeral in honour of the statesman.
他们为这位政治家举行了国葬。
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deportation
英汉讲解
n.驱逐；驱逐出境；放逐
参考例句
用作名词
Years ago convicted criminals in England could face deportation to Australia.
不少年以前，英国已定罪的犯人可能被驱逐到澳大利亚。
Deportation of criminals from England to Australia was once common.
把犯人从英国放逐到澳大利亚的作法在过去曾一度风靡。
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agent
困难程度：5星基本词语，属常用1000词
英汉讲解
n.代理人；代理商；药剂；特工职员
参考例句
用作名词
I have been instructed by my agent that you still owe me 100 pounds.
我的代理人公告我，你还欠我100磅。
The officer inspired the secret agent to murder the president .
这个军官鼓动这个特工职员去谋杀总统。
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respond
困难程度：4星核心词语，属常用3000词
英汉讲解
v.回答；响应；反应；反应灵敏；反响
n.[建]壁联；[宗]应唱圣歌
参考例句
用作动词
I invited her to dinner but she did not respond.
我请她吃晚饭，但她未作回答。
The professor lectured with a beaming countenance, but the students didn't respond much, only agreeing with what he said.
教授讲得眉飞色舞，学生们却没太大的反响，只不过随声应和。
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