Could it be a typo for "and one by one they will **be turned off**"? [CNN](http://edition.cnn.com/2011/OPINION/08/21/walkowicz.kepler.planets/index.html):

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> Many of the existing space telescopes, Hubble included, are nearing the end of their lifetimes, and one by one they will **turn off**. Without the James Webb Space Telescope, our eyes on the universe would be closed for the foreseeable future. 
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