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Inside a very big and very clean room at NASAs Goddard Space Flight Center in Greenbelt, Md., nearly 30 workers dressed in white protective suits, goggles and blue booties cluster around the parts of a time machine.

These parts gold-covered mirrors, tennis-court-size sun shields, delicate infrared cameras are slowly being put together to become the James Webb Space Telescope.

Astronomers are hoping that the Webb will be able to collect light that is very far away from us and is moving still farther away. The universe has been expanding ever since the big bang got it started, but scientists reckon that if the telescope is powerful enough, they just might be able to see the birth of the first galaxies, some 13.5 billion years ago.

This is similar to archaeology, says Harvard astrophysicist Avi Loeb, who helped plan Webbs science mission. We are digging deep into the universe. But as the sources of light become fainter and farther away, you need a big telescope like the James Webb.

Named for a former NASA director, the 21-foot-diameter Webb telescope will be 100 times as powerful as the Hubble Space Telescope, which was launched in 1990. Although Hubble wasnt the first space telescope, its images of far-off objects have dazzled the public and led to breakthroughs in astrophysics, such as determining how fast the universe is expanding.

The Webb will be both bigger and located in a darker part of space than Hubble, enabling it to capture images from the faintest galaxies. Four infrared cameras will capture light that is moving away from us very quickly and that has shifted from the visible to the infrared spectrum, described as red-shifted. The advantage of using infrared light is that it is not blocked by clouds of gas and dust that may lie between the telescope and the light. Webbs mirrors are covered in a thin layer of gold that absorbs blue light but reflects yellow and red visible light, and its cameras will detect infrared light and a small part of the visible spectrum. As objects move away from us, the wavelength of their light shifts from visible light to infrared light. Thats why the Webbs infrared cameras will be able to see things that are both far away and moving away from us.

The cameras will also probe the atmospheres of planets that revolve around nearby stars, known as exoplanets, for the chemical signatures of life: water, oxygen and maybe even pollution from alien civilizations.

But before any of that dazzling science happens, theres a lot of testing to do at Goddard, in the clean room and a nearby cryo-chamber.

Various tests will squeeze, shake, freeze and twist thousands of individual parts in an effort to make sure the spacecraft will survive blastoff from a spaceport in French Guyana and the cold environment of its orbiting position almost a million miles from Earth. By comparison, Hubble circles just 375 miles above our planet, depending on its orbit.

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NASA builds a time-machine telescope 100 times as powerful as the Hubble