VOA慢速英语2013 AS IT IS 2013-06-14 NASA Scientists Still Dream of, and Plan for, Human Travel to Mars

 

AS IT IS 2013-06-14 NASA Scientists Still Dream of, and Plan for, Human Travel to Mars

 

From VOA Learning English, this is As It Is.

Welcome back. I’m Caty Weaver¹.

On the show today, we look into the future of space exploration. The American space agency NASA has announced plans for a new effort to study the sun.

And, NASA scientists are considering new technologies for a possible human trip to the planet Mars. Newly released information about space radiation means the trip needs to take less time than is currently possible.

The American space agency is making final preparations for a project to study the sun. NASA scientists hope to observe the way solar material gathers energy and heats up as it moves through the sun’s lower atmosphere. Katherine Cole has more about the Interface² Regional Imaging Spectrograph, also called IRIS³.

The outer layer of the sun’s atmosphere, known as the corona⁴, is thousands of times hotter than the surface of the sun. Solar material heats up as it rises through the inner atmosphere to the corona.

Researchers want to know why this is. So they are preparing a mission to study what scientists call the sun’s “interface region.” This is the area between the corona and the sun’s photosphere⁵.

The energy and matter, called plasma⁶, that flow through the interface region have a major effect on Earth. This area is the source of the sun’s ultraviolet radiation. The radiation affects Earth’s climate. It also can influence the space environment near our planet. The energy that passes into the interface region is also responsible for solar wind.

Scientists believe the Interface Regional Imaging Spectrograph can help them understand the process. IRIS is a small satellite that can perform complex solar observations.

Alan Title is the IRIS lead investigator⁷. He is based at Lockheed Martin’s Advanced Technology Center in California.

“What we want to discover is what the basic physical processes are that transfer energy and material from the surface of the sun out to the outer atmosphere to the corona. And remember, the corona extends throughout the heliosphere. We live in the sun’s outer atmosphere.”

IRIS will provide highly detailed⁸ images that will show even individual structures of energy as they stretch away from the sun. NASA officials say the images will be three to four times as detailed as those from the agency’s Solar Dynamics⁹ Observatory¹⁰.

IRIS will also provide spectra¹¹. Spectra measures different wavelengths¹² of light at once.

NASA says IRIS will observe temperatures extending from about 5,000 to 65,000 degrees Celsius¹³. That number will rise to about ten million degrees during solar flares¹⁴. But, lead investigator Alan Title notes IRIS will keep a safe distance from the sun.

“IRIS flies around the Earth so it only gets about 600 kilometers closer to the sun than here we are on Earth, and that’s only about 92 million miles away. So it’s really not very much closer to the sun.”

The IRIS mission is expected to last two years and cost more than 180 million dollars. But scientists say the solar explorer could keep going much longer. IRIS is set to launch on a Pegasus XL rocket from a military base in California on June 26. I’m Katherine Cole.

Scientists, astronauts and space exploration fans have been dreaming about sending human beings to Mars for years. The American space agency has plans to make it happen by the middle of the 2030s. Recently, new information about a danger linked to the trip got NASA searching for solutions. Christopher Cruise tells us more.

NASA officials hope to send humans to Mars in about 20 years. But it is a goal that has technical and medical barriers.

New findings published in the journal Science suggest that a trip to Mars could give travelers a greater risk of radiation than NASA permits. Earlier research already has established that exposure to radiation increases a person’s risk of developing cancer.

The radiation measurements noted¹⁵ in the Science report were from the spaceship that carried the Rover exploratory vehicle to Mars in 2011. An instrument on the vehicle has been recording¹⁶ radiation levels since it landed on the red planet. It found that the amount of radiation exposure was a large fraction of what is considered an acceptable limit over an astronaut’s lifetime.

Cary Zeitlin is with the Southwest Research Institute in San Antonio, Texas. His team examined the radiation measures collected. This was done on the 253-day, 560 million kilometer trip to Mars. Cary Zeitlin says space travelers would face radiation exposure comparable to getting full body computed¹⁷ tomography x-rays every five to six days. He says the results are worrying.

“The concern is not so much any immediate¹⁸ effects on people, although those are possible, but long-term health effects like cancer, or damage to the central nervous system.”

Humans traveling on a spacecraft to Mars would be exposed to two kinds of radiation. One is low-energy particles called Galactic Cosmic Rays, or GCRs. The other is solar particle radiation, which depends on sun spot activity.

Mr. Zeitlin says improvements in protective equipment might help keep astronauts safe from the solar radiation. But he says the cosmic rays are a bigger problem.

“They can typically go through several inches of solid matter shielding without being attenuated¹⁹ (reduced) very much. So astronauts in deep space will get a continuous low radiation dose.”

He and his team will continue to take radiation measurements as the rover Curiosity continues to explore. Researchers want a complete picture of the radiation risks involved in human travel to Mars.

I’m Christopher Cruise.

NASA experts are considering these numbers on radiation levels in their early planning for a mission to Mars. Some scientists say the answer might be improvements in the driving force of spacecraft. They say new propulsion technologies are needed to shorten the time it takes to get to Mars. This would reduce the time a person is exposed to the radiation along the way.

Chris Moore leads NASA’s advanced exploration systems program. He says engineers are working on systems that could cut a trip to Mars from 250 to 180 days.

Eddie Semones is a space flight radiation health officer for NASA. He says a trip to Mars would require higher speed and protective equipment elements. But, he says the protection requires materials too heavy for a successful launch.

And that’s As It Is for today. Thanks for joining us.

1 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

2 interface   

n.接合部位，分界面；v.(使)互相联系

参考例句：

• My computer has a network interface,which allows me to get to other computers.我的计算机有网络接口可以与其它计算机连在一起。
• This program has perspicuous interface and extensive application. 该程序界面明了，适用范围广。

3 iris   

n.虹膜，彩虹

参考例句：

• The opening of the iris is called the pupil.虹膜的开口处叫做瞳孔。
• This incredible human eye,complete with retina and iris,can be found in the Maldives.又是在马尔代夫，有这样一只难以置信的眼睛，连视网膜和虹膜都刻画齐全了。

4 corona   

n.日冕

参考例句：

• The corona gains and loses energy continuously.日冕总是不断地获得能量和损失能量。
• The corona is a brilliant,pearly white,filmy light,about as bright as the full moon.光环带是一种灿烂的珠白色朦胧光，几乎像满月一样明亮。

5 photosphere   

n.光球

参考例句：

• The photosphere has a granular structure.光球还有颗粒结构。
• The chromosphere is a frothy layer churned up by gases in the photosphere.色球层在光球层气体的搅拌下是个多泡层。

6 plasma   

n.血浆，细胞质，乳清

参考例句：

• Keep some blood plasma back for the serious cases.留一些血浆给重病号。
• The plasma is the liquid portion of blood that is free of cells .血浆是血液的液体部分，不包含各种细胞。

7 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。

8 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。

9 dynamics   

n.力学，动力学，动力，原动力；动态

参考例句：

• In order to succeed,you must master complicated knowledge of dynamics.要取得胜利，你必须掌握很复杂的动力学知识。
• Dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。

10 observatory   

n.天文台，气象台，瞭望台，观测台

参考例句：

• Guy's house was close to the observatory.盖伊的房子离天文台很近。
• Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。

11 spectra   

n.光谱

参考例句：

• The infra-red spectra of quinones present a number of interesting features. 醌类的红外光谱具有一些有趣的性质。
• This relation between the frequency and the field spectra was noted experimentally. 实验上已经发现频率和场频谱之间的这种关系。

12 wavelengths   

n.波长( wavelength的名词复数 )；具有相同的/不同的思路；合拍；不合拍

参考例句：

• I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话，因为我们俩完全不对路。 来自《简明英汉词典》
• Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句

13 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

14 flares   

n.喇叭裤v.（使）闪耀( flare的第三人称单数 )；（使）（船舷）外倾；（使）鼻孔张大；（使）（衣裙、酒杯等）呈喇叭形展开

参考例句：

• The side of a ship flares from the keel to the deck. 船舷从龙骨向甲板外倾。 来自《简明英汉词典》
• He's got a fiery temper and flares up at the slightest provocation. 他是火爆性子，一点就着。 来自《现代汉英综合大词典》

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 recording   

n.录音，记录

参考例句：

• How long will the recording of the song take?录下这首歌得花多少时间？
• I want to play you a recording of the rehearsal.我想给你放一下彩排的录像。

17 computed   

adj.[医]计算的，使用计算机的v.计算，估算( compute的过去式和过去分词 )

参考例句：

• He computed that the project would take seven years to complete. 他估计这项计划要花七年才能完成。 来自《简明英汉词典》
• Resolving kernels and standard errors can also be computed for each block. 还可以计算每个块体的分辨核和标准误差。 来自辞典例句

18 immediate   

adj.立即的；直接的，最接近的；紧靠的

参考例句：

• His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。
• We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。

19 attenuated   

v.（使）变细( attenuate的过去式和过去分词 )；（使）变薄；（使）变小；减弱

参考例句：

• an attenuated form of the virus 毒性已衰减的病毒
• You're a seraphic suggestion of attenuated thought . 你的思想是轻灵得如同天使一般的。 来自辞典例句