美国国家公共电台 NPR Some Assembly Required: New Space Telescope Will Take Shape After Launch

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Some Assembly Required: New Space Telescope Will Take Shape After Launch

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Now, the massive James Webb Space Telescope is heading into its final round of ground tests. The nearly $9 billion observatory² will replace the aging Hubble Space Telescope, and astronomers³ are giddy about the wealth of new information they expect to gain if they get the telescope to work. NPR's Joe Palca reports.

JOE PALCA, BYLINE⁴: A virtual army of scientists and engineers has been laboring⁵ to get the new telescope ready for launch. Astrophysicist and systems engineer Begona Vila is a relative newcomer on the project.

BEGONA VILA: Oh, only 10 years.

PALCA: Vila works at the Goddard Space Flight Center in Greenbelt, Md. It's here that the telescope's mirrors and instruments are frozen, shaken and rattled⁶ to make sure they'll survive their trip to a spot a million miles from Earth. Unlike Hubble, the James Webb telescope is primarily designed to look at the universe at what's called infrared⁷ wavelengths⁸. This allows it to peer through dust clouds and to see how the earliest stars and galaxies⁹ formed. But to work properly, infrared telescopes have to be kept cold - very cold. Vila says the Webb telescope uses a multi-layered sunshield to protect it from the sun's heat.

VILA: That's like a big umbrella - beach umbrella - so we keep that facing the sun and the Earth so all the heat on it dissipates - all the heat through the layers. So that allows all the instruments to cool to the temperatures that we need.

PALCA: Now, the sunshield is big - about the size of a tennis court. And for launch, it has to fit into a much smaller space - about the size of a school bus. So the sunshield has to fold up, as does the large main mirror and a variety of other essential instruments. The unfolding takes place in a carefully choreographed¹⁰ sequence of steps over two weeks.

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UNIDENTIFIED WOMAN #1: Solar panels extend.

ARI SHAPIRO, BYLINE: Antenna¹¹ deployment¹³.

DAVID GREENE, BYLINE: Forward sunshield panel deployment.

PALCA: Each step is critical. No solar panels, no power. No antenna, no communications. No forward sunshield, no cooling.

SHAPIRO: Aft sunshield panel deployment.

UNIDENTIFIED WOMAN #2: Aft membrane¹⁴ cover release

UNIDENTIFIED WOMAN #1: First sunshield mid-boom deployment.

PALCA: And finally, the two wings that hold the key parts of the telescope's main mirror have to unfold. If everything deploys¹⁵ as it should, the telescope is ready for business. But it's a lot of things that have to deploy¹² just right. So I asked Begona Vila, doesn't that scare you?

VILA: Yes, I think it scares all of us.

PALCA: She says there's really no way around it.

VILA: We do as much testing as we can, as thorough a test as we can. And we also have multiple review teams that check results and make sure that we are not missing anything and that, you know, we are doing the best we can to confirm everything is going to work.

PALCA: Already way over its initial budget and behind schedule, the Webb telescope is supposed to launch in October 2018. We should know later that year whether all those tests and reviews missed anything crucial. Joe Palca, NPR News.