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US Space Agency Expands Search for Distant Planets Able to Support Life

The search for worlds orbiting distant stars will intensify¹ in the coming weeks when the American space agency NASA launches a spacecraft.

Scientists hope the spacecraft will enlarge the known list of planets that they believe can support life as we know it.

The space agency plans to launch the Transiting³ Exoplanet Survey Satellite, or TESS, from the Cape⁴ Canaveral Air Force Station in Florida. NASA will be using a Falcon⁵ 9 rocket from a private company, SpaceX, to send TESS into Earth orbit.

Officials say the launch could take place as soon as April 16. They expect the satellite’s mission to last about two years and cost $337 million.

The latest NASA astrophysics effort is designed to build on the work of the Kepler space telescope. Scientists used the telescope to discover most of the almost 3,500 exoplanets documented during the past 20 years. Their discovery completely changed one of the newest fields in space science.

NASA researchers expect TESS to find thousands more formerly⁶ unknown worlds. They believe hundreds of these planets could be Earth-sized or “super-Earth”-sized — meaning they are no larger than twice as big as our home planet.

Experts believe such worlds hold the greatest chance of having rocky surfaces or oceans. This means they would be the most promising⁷ candidates for life, unlike large, gas-based planets similar to Jupiter or Neptune⁸.

Astronomers⁹ said they hope to find about 100 more rocky exoplanets for future study.

The new satellite will take about 60 days to reach its special, first-of-a-kind orbit. This will send TESS between Earth and the moon every two and a half weeks.

Kepler’s positioning system stopped working in 2013, about four years after its launch. Scientists found a way to keep the telescope operating. But it has now used nearly all of its fuel.

Paul Hertz, NASA’s director of astrophysics, spoke¹⁰ to reporters in late March. He said, “It’s perfect timing¹¹ that we’ll be launching TESS to continue the great activity of looking for planets around stars other than our sun and thinking about what it might mean for life in the universe.”

TESS is about the size of a refrigerator. Its wings have equipment to collect energy from the sun. And it also carries four special cameras to examine 200,000 stars that are relatively¹² near the sun. These are the brightest stars in the sky. TESS will seek to identify which have planets of their own.

Like Kepler, TESS will use a method called transit² photometry to identify unknown planets. Researchers will look for periodic, repetitive decreases in the visible light from stars caused by planets passing in front of them.

But Kepler only looked for stars within a very small part of the sky. TESS will examine the majority of the sky for shorter periods. It will also direct much of its attention on stars called red dwarfs¹⁴, which are smaller, cooler and longer-lived than our sun.

One reason it will do so is that red dwarfs are more likely to have Earth-sized, possibly rocky planets orbiting them, noted¹⁵ David Latham. He is the TESS science director for the Harvard-Smithsonian Center for Astrophysics. He noted such planets are possibly fertile ground for closer examination.

Latham said another reason red dwarfs are important is that they are smaller and their planets orbit more closely than the Earth does to the sun. So a decrease in light from a planet passing in front of a red dwarf¹³ is easier to detect than with a larger star.

“It’s easier to find interesting planets around smaller stars,” he said.

Measuring decreases in starlight can identify an exoplanet’s size and orbital path. Further observations from ground telescopes can provide its mass, as well as its density¹⁶ and whether it is largely solid, liquid or gas.

Martin Still is the TESS program scientist for NASA. He said more than 50 rocky, Earth- or super-Earth-sized planets have been identified already. And NASA expects to increase that number through the new mission.

The most promising discoveries are to be examined by a new generation of larger, more powerful telescopes now under development. These will search for signs of water and “the kinds of gases in their atmospheres that on Earth are an indication of life,” Hertz said.

“TESS itself will not be able to find life beyond Earth, but TESS will help us figure out where to point our larger telescopes,” he said.

I’m Pete Musto.

Words in This Story

exoplanet – n. a planet that orbits a star outside the area of space that includes our sun and the planets moving around it

mission – n. a task or job that someone is given to do

astrophysics – n. the scientific study of the physical and chemical properties and structures of stars, planets, and other objects in outer space

refrigerator – n. a device or room that is used to keep things such as food and drinks cold

visible – adj. able to be seen

detect – v. to discover or notice the presence of something that is hidden or hard to see, hear, or taste

indication – n. something such as a sign or signal that points out or shows something

1 intensify   

vt.加强；变强；加剧

参考例句：

• We must intensify our educational work among our own troops.我们必须加强自己部队的教育工作。
• They were ordered to intensify their patrols to protect our air space.他们奉命加强巡逻，保卫我国的领空。

2 transit   

n.经过，运输；vt.穿越，旋转；vi.越过

参考例句：

• His luggage was lost in transit.他的行李在运送中丢失。
• The canal can transit a total of 50 ships daily.这条运河每天能通过50条船。

3 transiting   

通过（transit的现在分词形式）

参考例句：

• The effect of the transiting mechanic required reserve system vehicle is low. 准备金制度的传导机制的作用是很低的。
• I was busy transiting to the telescope. 我正忙着旋转望远镜。

4 cape   

n.海角，岬；披肩，短披风

参考例句：

• I long for a trip to the Cape of Good Hope.我渴望到好望角去旅行。
• She was wearing a cape over her dress.她在外套上披着一件披肩。

5 falcon   

n.隼，猎鹰

参考例句：

• The falcon was twice his size with pouted feathers.鹰张开羽毛比两只鹰还大。
• The boys went hunting with their falcon.男孩子们带着猎鹰出去打猎了。

6 formerly   

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。

7 promising   

adj.有希望的，有前途的

参考例句：

• The results of the experiments are very promising.实验的结果充满了希望。
• We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。

8 Neptune   

n.海王星

参考例句：

• Neptune is the furthest planet from the sun.海王星是离太阳最远的行星。
• Neptune turned out to be a dynamic,stormy world.海王星原来是个有生气、多风暴的世界。

9 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• 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。 来自《简明英汉词典》

10 spoke   

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。

11 timing   

n.时间安排，时间选择

参考例句：

• The timing of the meeting is not convenient.会议的时间安排不合适。
• The timing of our statement is very opportune.我们发表声明选择的时机很恰当。

12 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

13 dwarf   

n.矮子，侏儒，矮小的动植物；vt.使…矮小

参考例句：

• The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
• The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀，摇摇头。

14 dwarfs   

n.侏儒，矮子（dwarf的复数形式）vt.（使）显得矮小（dwarf的第三人称单数形式）

参考例句：

• Shakespeare dwarfs other dramatists. 莎士比亚使其他剧作家相形见绌。 来自《简明英汉词典》
• The new building dwarfs all the other buildings in the town. 新大楼使城里所有其他建筑物都显得矮小了。 来自辞典例句

15 noted   

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。

16 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。