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#13
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09-09-2011, 05:50 PM
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Re: Huge Satellite to Plunge to Earth: NASA
WHAT HAPPENS WHEN A SATELLITE FALLS TO EARTH? Astronomer Dr Ian Griffin, from the UK Association of Science and Discovery Centres, says the Earth's atmosphere slows down falling satellites a great deal. He explained that what remains of UARS will hit the ground relatively slowly and 'certainly not at orbital velocity of 17,500mph'. Much of any satellite crashing to Earth will be disintegrated by heat, caused by friction with the atmosphere. It's the reason we get shooting stars - created by meteors burning up in the upper atmosphere. UARS is large enough, though, that up to half a ton will strike the ground. It will probably not be in one piece, however: space vehicles experience incredible stress on re-entry. The load can be as much as 10Gs. An F1 car experiences around 5Gs with maximum braking from high speed. The reason why the location of the crash site is so hard to predict is because the density of the atmosphere varies so greatly higher up, producing different amounts of drag. A prediction that was wrong by even a few minutes would mean the satellite landing a huge distance away, owing to its speed. |