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Rosetta: Alarm to sound for comet mission

20 January 2014 Last updated at 05:58 GMT

One of the most daring space missions ever undertaken reaches a key milestone on Monday.

Europe's Rosetta probe was launched a decade ago on a long quest to chase down and land on a comet, and has spent the past two-and-a-half-years in hibernation to try to conserve power.

Rebecca Morelle reports.