Christopher Hart
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Virgin crash investigation 'could take year'

US officials have started to investigate why a Virgin Galactic space rocket crashed over California's Mojave Desert on a test flight.

NTSB acting chairman Christopher Hart said the team expected to be at the crash site for four to seven days, but added that the full investigation could take up to 12 months to complete.

Virgin Galactic would be free to conduct further flights during that time, he added.

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