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外媒解析为何卫星难以找到马航失联客机

2014-03-27 10:07   类别:阅读   来源:BBS   责编:erwine
导学:为何能看到车牌的卫星找不到庞大的波音777客机?


卫星为何难以发现马航370

原载于华盛顿邮报,第三页有中文翻译:
Malaysia Airlines Flight MH370 search tests limits of satellites

By Joel Achenbach and Scott Higham, Published: March 21 E-mail the writers

The disappearance of Malaysia Airlines Flight MH370 has exposed the technological limits of satellites, which can see a license plate from space — if not necessarily read it — but struggle to find a missing jetliner.

These limits are shaped by physics, money and practicality. Military and commercial satellites are not closely observing and amassing data about the blank places on the map in lightly traveled seas — such as remote areas of the Indian Ocean thousands of miles from where Flight MH370 vanished from radar.

There’s also a trade-off when scrutinizing the surface from space: You can go wide or you can go deep, but you can’t do both. The most sophisticated spy satellites are essentially looking down straws, trying to resolve small details in a narrow field of view.

“Imagine driving down the street at 70 miles an hour with a pair of binoculars and trying to look at every single mailbox,” said Brian Weeden, technical adviser to the Secure World Foundation, a nonprofit organization devoted to space policy. “You can’t slew your binoculars around fast enough.”

The satellites may yet prove triumphant in this baffling case. There is tantalizing imagery of possible debris from the missing plane that has been made public by Australian officials, taken by WorldView-2, a high-resolution commercial satellite circling the planet at an altitude of 470 miles.

It’s unclear what’s in the images. The primary object, if it is an object and not some trick of light, was seen on March 16 — eight days after Flight MH370 disappeared — in the southern Indian Ocean about 1,500 miles west of Perth, Australia.

Nothing has been spotted by aircraft or satellites in that location in the days since, officials have said. If the mystery object is part of the plane, it means the Boeing 777 flew from the Equator almost halfway to the South Pole.

“It looks to me like possibly just an exceptionally large patch of sun glint,” said John Amos, president of SkyTruth, which uses satellite imagery to raise awareness of environmental issues. “We’re down in the subtle and ambiguous weeds of human image analysis, where we desperately are trying to find patterns in what we’re seeing.”

The company that owns WorldView-2, Colorado-based DigitalGlobe, said the lengthy period of analysis between the day the satellite obtained the image and when the Australians released it to the public is a reflection of the daunting nature of combing through so much data.

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