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This is the VOA Special English Technology Report.
If you could build a time machine, what would it look like? Maybe, it should look like a telescope. American scientists are building a space telescope, they hope, will look back over unimaginable distances and time to show the universe close to its beginning.
But this distant past will mainly be seen in infrared light. Visible light is just one form of radiation. Today, telescopes take pictures using forms of light hidden from the human eye.
The American space agency, NASA, is now building the largest space telescope ever. The James Webb Space Telescope, named after NASA's second director, will have a mirror seven times the size of the Hubble Space Telescope.
But it will mainly study the universe in infrared light. We usually experience infrared light as heat. But, if you have ever used a TV remote control, you know there are many uses for it.
The James Webb Space Telescope is a complex engineering project. It will be huge -- about the size of a passenger jet. And it will have to be super-cooled. Because the telescope studies infrared heat, its mirror must be kept very close to absolute zero. That is minus 273 degrees Celsius.
NASA is building the Webb telescope at the Goddard Space Center, outside Washington DC. The agency hopes to launch it in 2014.
Jonathan Gardner is a project scientist for the telescope. We asked him how the device can look back in time.
JONATHAN GARNER: "We can see back in time because light takes time to get from there to here. So, as we look further and further away, it takes longer and longer for the light to get from where it's emitted to here and we can actually see backwards in time.
And if you look far enough, you start to approach the event scientists believe gave birth to everything.
JONATHAN GARNER: "We're looking (at the universe when it was much younger and we're looking) back most of the way to the Big Bang."
The telescope has three highly sensitive infrared cameras. But perhaps its most interesting part is the 6.5 meter wide mirror. Made of light-weight beryllium, the mirror is covered in gold, and divided into 18 linked parts.
This powerful scientific instrument will be available to scientists all over the world.
JONATHAN GARNER: "Any astronomer, at any university, in any country can write a proposal for what they want to do with the telescope."
Jonathan Gardner says the Jim Webb Space Telescope will help scientists learn how the first galaxies formed and what they looked like. It may even show things scientists never predicted.
And that's the VOA Special English Technology Report. written by George Putic. Watch video about the James Webb Space Telescope at voaspecialenglish.com. I'm Mario Ritter.
infrared: having or using electromagnetic waves which are longer than those of red light in the spectrum, and which cannot be seen 紅外線的；使用紅外線的
beryllium: the chemical element of atomic number 4, a hard gray metal【化】鈹
Discovery preps for last space mission
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（來源：VOA 編輯：崔旭燕）
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