AILSA CHANG, HOST:
A prototype space station, put into orbit by China, will soon be falling back to Earth. It is the size of a city bus. No one knows where parts of it will land although regions of the continental U.S. are in the potential crash zone. But as NPR's Nell Greenfieldboyce reports, you have nothing to worry about.
NELL GREENFIELDBOYCE, BYLINE: China sent up this orbiting lab in 2011. It's called Tiangong-1. The name means heavenly palace. And it was briefly visited twice by Chinese taikonauts, like Wang Yaping who beamed down a science lecture from space on the side.
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WANG YAPING: (Through interpreter) Look at these lovely, beautiful, little droplets. Does it remind you of the word translucent?
GREENFIELDBOYCE: She showed how drops of water would float in midair in front of the red flag of China. Joan Johnson-Freese is a professor at the Naval War College. She says the Tiangong-1 is part of a methodical program that China has been following since 1992...
JOAN JOHNSON-FREESE: ...To demonstrate human spaceflight and culminate with a large space station.
GREENFIELDBOYCE: That future station would be smaller than the International Space Station but still huge and a more permanent home in space. For that, China needs experience with things like spaceship docking and long-term life-support. So Tiangong-1 and another heavenly palace, Tiangong-2...
JOHNSON-FREESE: ...Have been technology test bed laboratories to do experimentation on all those different areas and more.
GREENFIELDBOYCE: Now though Tiangong-1 is headed back down. And even though space junk this size falls to Earth a few times a year, it's usually something like a spent rocket stage not a home away from home for astronauts. Bill Ailor is an expert on orbital debris at the Aerospace Corporation.
BILL AILOR: These kinds of events are noteworthy. And people in this business kind of watch to see what they can learn about how these things come apart as they come down.
GREENFIELDBOYCE: He says most of the 19,000 pound lab should burn up - though not all of it.
AILOR: Somewhere between, say, 2,000 and 8,000 pounds might come down...
GREENFIELDBOYCE: ...In a zone that covers about two-thirds of the globe, including a lot of the continental United States. Exactly where and when is hard to know because the vehicle will interact with the atmosphere, which is constantly changing. The fiery re-entry is currently predicted to happen sometime in a window that covers the last few days of March and the first few days of April. Ailor says don't worry about getting hit.
AILOR: You know, it's just not a very likely event that any particular person would have a problem with it.
GREENFIELDBOYCE: He says in 60 years of space exploration, only one person, an American woman named Lottie Williams, has been struck by falling space junk.
AILOR: And it was just like a piece of fabric material that kind of brushed her on the shoulder.
GREENFIELDBOYCE: He says hopefully someone will get to see the bright streaks created by Tiangong-1 breaking up and burning.
AILOR: It would be a beautiful thing to watch.
GREENFIELDBOYCE: But since most of our planet is covered by oceans, he says the most likely scenario is that it will come down over the water and never be seen or heard from again. Nell Greenfieldboyce, NPR News.
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