Alan Fitzsimmons, an astronomer from Queen's University Belfast, said: "When it does pass close to us on April 13 2029, the Earth will deflect it and change its orbit. There's a small possibility that if it passes through a particular point in space, the so-called keyhole, ... the Earth's gravity will change things so that when it comes back around again in 2036, it will collide with us." The chance of Apophis passing through the keyhole, a 600-metre patch of space, is 1 in 5,500 based on current information.So the odds are much, much better than winning the lottery, but they are still 1 in 5,500. I’d say it’s not time to panic. Especially when they are planning to do something about it.
The favoured method is also potentially the easiest - throwing a spacecraft at an asteroid to change its direction. Esa plans to test this idea with its Don Quixote mission, where two satellites will be sent to an asteroid. One of them, Hidalgo, will collide with the asteroid at high speed while the other, Sancho, will measure the change in the object's orbit.Now that would be a cool job. Bumper cars in space. Smash and crash. Ooh boy!
But there is no time to waste. Even if the ultimate collision is predicted for 2036, the Smash&Crash would be best done in 2013 when Apophis is a leeeetle further away from Earth.
"It may be a decision in 2013 whether or not to go ahead with a full-blown mitigation mission, but we need to start planning it before 2013," said Prof Fitzsimmons. In 2029, astronomers will know for sure if Apophis will pose a threat in 2036. If the worst-case scenarios turn out to be true and the Earth is not prepared, it will be too late. "If we wait until 2029, it would seem unlikely that you'd be able to do anything about 2036," said Mr Yates
Then there is this more reassuring article in which the chance of astrophysical catastrophe is down played. (Although I note the lack of asteroids in their discussion.)
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