James Webb Telescope

The next generation of great space telescopes is heading into its final round of ground tests.

The nearly $9 billion James Webb Space Telescope will replace the aging Hubble Space Telescope. It's designed to provide unprecedented images of the earliest stars and galaxies that formed in the universe, NPR reports.

The Webb telescope is designed to look at the infrared wavelengths of light given off by stars. Infrared is needed to see some of the earliest stars and galaxies that formed billions of years ago.

But to work properly, according to the NPR report, infrared telescopes have to be kept cold — very cold. So engineers had to design a multilayered sun shield to protect the telescope from the sun's heat.

"That's like a big umbrella — beach umbrella — so, we keep that facing the sun and the Earth so it dissipates all the heat through all the layers," Begoña Vila, an astrophysicist and systems engineer at NASA's Goddard Space Flight Center, in Greenbelt, Md, told NPR. "That allows all the instruments to cool to the temperatures that we need."

The sun shield, however, is about the size of a tennis court, but during the launch it has to be able to fit into a far smaller space.

So engineers had to come up with a way to fold it up. They also had to design a way to fold up the main mirror, and several other critical instruments, NPR reported.

Then, after launch, everything has to unfold in a carefully choreographed sequence of steps over two weeks.

The deployment phase will be nerve-wracking: "Yes, I think that scares all of us," says Vila. But there's no way around it. "We do as much testing as we can."

According to NPR: The Webb telescope has had a difficult history. It is over budget and behind schedule, and Congress nearly killed the project earlier in the decade.

The telescope is scheduled to launch in October 2018.

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