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VOA慢速英语2011--The Evolution of Spacesuits

时间:2011-04-07 08:16:21

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EXPLORATIONS - The Evolution of Spacesuits

 

STEVE EMBER: I’m Steve Ember.
SHIRLEY GRIFFITH: And I’m Shirley Griffith with the VOA Special English program EXPLORATIONS. Today we tell about the special clothes astronauts wear that protect them while they work in space.
(MUSIC)
STEVE EMBER: Many questions had to be answered over sixty years ago when officials first began to think about placing a human being in space. One of the most important was how to design the special clothing needed to protect a person from the dangers of the space environment.
A person cannot work in the extremes of space without many different kinds of protection. The cold of space will freeze skin in a short time. The fierce heat of the sun can cause severe burns. The lack of atmosphere can cause gases and fluids in the body to expand and even burst.
And, with no oxygen to breathe, a human being will die in only a few moments. Any of these extreme conditions would mean a quick death for someone who did not wear special protective clothing. Ultraviolet1 radiation from the sun is another environmental risk in space. So is damage from small pieces of rock and objects like meteoroids.
Astronaut Jeffrey Williams during a six-hour spacewalk outside the International Space Station
SHIRLEY GRIFFITH: When humans explore and do useful work in space, they must take their natural environment with them. The American space agency, NASA, provides astronauts with a number of things that work together to create a protective environment. An astronaut who does work outside the space shuttle usually is wearing more than seventeen pieces of protective equipment.
STEVE EMBER: The atmosphere is about twenty-percent oxygen and eighty percent nitrogen from Earth’s surface to where space begins at one-hundred-twenty kilometers up. Yet up at about five-thousand-four hundred meters the air pressure is only about half of what it is on the ground. At about nineteen-thousand meters, the air is so thin and the amount of oxygen so small that a person needs a lot of special equipment to survive.
A well-known American flyer, Wiley Post, designed one of the first successful devices to protect a pilot at extreme heights. In nineteen-thirty-three, he developed protective clothing that made it possible for him to fly very high. Today, aircraft are designed to prevent air pressure changes at extreme heights. But this was not yet possible in nineteen thirty-three.
SHIRLEY GRIFFITH: Wiley Post made this protective clothing with the help of the Phillips Petroleum2 Company and the BF Goodrich Company. It appeared to be something a person would wear to stay underwater for long periods of time. A large device that looked like a can surrounded the pilot’s head. A small window in the front permitted him to see.
Wiley Post’s protective clothing was made of rubber. It could hold oxygen and provide the needed air pressure to protect his body from the lack of pressure at extreme heights. This protective suit was only used a few times, but it permitted Mr. Post to fly as high as fifteen-thousand meters. That was higher than any person had ever flown. Mister Post did not know it, but he had designed the first real spacesuit. His suit is now part of the collection of the Smithsonian Institution’s Air and Space Museum in Washington, DC.
(MUSIC)
STEVE EMBER: Astronauts in NASA’s Mercury3 Program flew the first American space flights in the early nineteen-sixties. Each set of protective clothing was specially4 made for each astronaut. The clothing was similar to that invented by Wiley Post. And, it presented some of the same problems.
When air pressure filled the early spacesuit, astronauts found it difficult to move their arms or legs. It was a little like trying to change the shape of a balloon. The pressure inside the suit provided protection, but made it difficult for the astronaut to move in a natural way.
Mercury astronauts usually wore the suit without air pressure inside. The Mercury spacecraft had the needed atmospheric5 pressure to keep the astronauts safe. The astronauts wore the suit as a safety device in case the spacecraft suddenly lost air pressure.
SHIRLEY GRIFFITH: Today, astronauts wear very different protective clothing. It lets them move, do useful tasks, and stay outside their spacecraft in comfort and safety for several hours.
For the next few minutes, imagine you are in the space shuttle about to go out to work in space.
STEVE EMBER: You will wear a spacesuit to work in the open cargo6 area of the Space Shuttle Discovery, which returned from its last flight last month. The spacesuit is called the shuttle extravehicular mobility7 unit or EMU. It was designed to last longer and to permit more movement than earlier spacesuits.
The EMU has a number of parts that an astronaut can link together by using only one hand. The different parts are in different sizes. This makes it possible for each astronaut to select the parts that fit correctly.
Wearing the whole EMU can add as much as ninety kilograms to your weight. Yet, the lack of gravity in space means you will not feel the added weight.
SHIRLEY GRIFFITH: You will be wearing equipment that will send medical information back to the NASA control center in Houston, Texas. Doctors will observe your medical condition while you work in space.
You also will wear a device that will collect urine, the body’s liquid waste. You will be working outside the space shuttle for about five hours. This collection device can become very necessary.
STEVE EMBER: You will also wear something called the Liquid Cooling and Ventilation Garment. This piece of clothing is worn next to the skin. It helps keep the body cool by moving water through many small tubes that cover the device. The heat from the sun can reach one-hundred-twenty degrees Celsius8 in orbit. The material of the space suit helps protect against this heat. The liquid cooling device also works to keep your body from becoming too hot.
SHIRLEY GRIFFITH: You will also put on a container that holds water to drink. A small tube stays near your mouth so you can drink water during your stay in space. A special hat on your head is made of soft cloth. It also carries several communications devices including earphones and microphones. These communication devices will permit you to talk with other astronauts working outside the shuttle and with crew members inside the shuttle. You can also talk with the control center in Houston, Texas.
The lower part of the spacesuit is next. It is called the Lower Torso Assembly. It is like putting on a large pair of pants that have boots built in the bottom of the legs.
STEVE EMBER: Next comes the upper part of the spacesuit. It is made of a hard plastic-like material. To put it on, you must hold your arms over your head, and rise up into the upper part of the suit. The upper part of the suit also holds the Primary Life Support System.
The life support system supplies the oxygen needed for breathing and the air pressure necessary to protect your body. The upper part of the spacesuit also carries an emergency oxygen system in case the first system fails.
An important part of your spacesuit is the control module9. It lets you observe and control your oxygen system. It is also the place you find the controls for your communications equipment. And, it tells you if you are having a problem with any of the spacesuit’s devices.
An astronaut tests a Mark III space suit designed for the Constellation10 program in 2007
SHIRLEY GRIFFITH: NASA scientists are also considering the kind of spacesuits that would be needed for exploration on the planet Mars11. Because of the gravity on Mars, spacesuits may have to be designed to be lighter12 than suits used in orbit or on the moon. The equipment may also have to protect astronauts from dust carried in the winds on Mars. And, they must be easy to repair and keep clean during a longer flight to and from the red planet.
STEVE EMBER: All of the spacesuits that have returned from space belong to the Smithsonian Institution. Most of the suits are stored in a building about ten kilometers from Washington.
They are kept in a room where air temperature and moisture levels are carefully controlled. The old spacesuits break easily. They were designed to protect the astronaut, and how they would last after a space operation was not a big consideration. Smithsonian experts must pay special attention to protect these suits because they help to tell the story of space exploration.
(MUSIC)
SHIRLEY GRIFFITH: This Special English program was written by Paul Thompson and Dana Demange, who was also the producer. I’m Shirley Griffith.
STEVE EMBER: And I’m Steve Ember. You can find our series online with transcripts13, MP3s, podcasts and images at voaspecialenglish.com. You can also follow us on Facebook and Twitter at VOA Learning English. Join us again next week for another EXPLORATIONS program on the Voice of America.


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点击收听单词发音收听单词发音  

1 ultraviolet vlJwd     
adj.紫外线的;n.紫外线
参考例句:
  • It's called ultraviolet rays.它被叫做紫外线。
  • The sun's ultraviolet rays are responsible for both tanning and burning.阳光中的紫外线是皮肤晒黑和灼伤的根源。
2 petroleum WiUyi     
n.原油,石油
参考例句:
  • The Government of Iran advanced the price of petroleum last week.上星期伊朗政府提高了石油价格。
  • The purpose of oil refinery is to refine crude petroleum.炼油厂的主要工作是提炼原油。
3 mercury NouzIB     
n.汞,水银,水银柱
参考例句:
  • The liquid we can see in thermometers is mercury.我们看到的温度计里的液体是水银。
  • Mercury has a much greater density than water.水银的密度比水大得多。
4 specially Hviwq     
adv.特定地;特殊地;明确地
参考例句:
  • They are specially packaged so that they stack easily.它们经过特别包装以便于堆放。
  • The machine was designed specially for demolishing old buildings.这种机器是专为拆毁旧楼房而设计的。
5 atmospheric 6eayR     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
6 cargo 6TcyG     
n.(一只船或一架飞机运载的)货物
参考例句:
  • The ship has a cargo of about 200 ton.这条船大约有200吨的货物。
  • A lot of people discharged the cargo from a ship.许多人从船上卸下货物。
7 mobility H6rzu     
n.可动性,变动性,情感不定
参考例句:
  • The difference in regional house prices acts as an obstacle to mobility of labour.不同地区房价的差异阻碍了劳动力的流动。
  • Mobility is very important in guerrilla warfare.机动性在游击战中至关重要。
8 Celsius AXRzl     
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。
9 module iEjxj     
n.组件,模块,模件;(航天器的)舱
参考例句:
  • The centre module displays traffic guidance information.中央模块显示交通引导信息。
  • Two large tanks in the service module held liquid oxygen.服务舱的两个大气瓶中装有液态氧。
10 constellation CptzI     
n.星座n.灿烂的一群
参考例句:
  • A constellation is a pattern of stars as seen from the earth. 一个星座只是从地球上看到的某些恒星的一种样子。
  • The Big Dipper is not by itself a constellation. 北斗七星本身不是一个星座。
11 Mars 4oSz63     
n.火星,战争
参考例句:
  • As of now we don't know much about Mars.目前我们对火星还知之甚少。
  • He contended that there must be life on Mars.他坚信火星上面一定有生物。
12 lighter 5pPzPR     
n.打火机,点火器;驳船;v.用驳船运送;light的比较级
参考例句:
  • The portrait was touched up so as to make it lighter.这张画经过润色,色调明朗了一些。
  • The lighter works off the car battery.引燃器利用汽车蓄电池打火。
13 transcripts 525c0b10bb61e5ddfdd47d7faa92db26     
n.抄本( transcript的名词复数 );转写本;文字本;副本
参考例句:
  • Like mRNA, both tRNA and rRNA are transcripts of chromosomal DNA. tRNA及rRNA同mRNA一样,都是染色体DNA的转录产物。 来自辞典例句
  • You can't take the transfer students'exam without your transcripts. 没有成绩证明书,你就不能参加转学考试。 来自辞典例句

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