* Astronomy

Herschel intercepts asteroid Apophis

ESA's Herschel space observatory made new observations of asteroid Apophis as it approached Earth this weekend. The data shows the asteroid to be bigger than first estimated, and less reflective.
Catalogued as asteroid (99942) Apophis (previously 2004 MN4), it is often nicknamed 'the doomsday asteroid' in popular media, after initial observations made after its discovery in 2004 gave it a 2.7% chance of striking Earth in April 2029.
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Title: Yarkovsky-driven impact risk analysis for asteroid (99942) Apophis
Authors: D. Farnocchia, S. R. Chesley, P. W. Chodas, M. Micheli, D. J. Tholen, A. Milani, G. T. Elliott, F. Bernardi

We assess the risk of an Earth impact for asteroid (99942) Apophis by means of a statistical analysis accounting for the uncertainty of both the orbital solution and the Yarkovsky effect. We select those observations with either rigorous uncertainty information provided by the observer or a high established accuracy. For the Yarkovsky effect we perform a Monte Carlo simulation that fully accounts for the uncertainty in the physical characterization, especially for the unknown spin orientation. By mapping the uncertainty information onto the 2029 b-plane and identifying the keyholes corresponding to subsequent impacts we assess the impact risk for future encounters. In particular we find an impact probability greater than 10^-6 for an impact in 2068. We analyse the stability of the impact probability with respect to the assumptions on Apophis' physical characterisation and consider the possible effect of the early 2013 radar apparition.

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Doomsday device: Russian beacon to track menacing asteroid Apophis

Russia's space agency wants to send a mission to Apophis, the notorious asteroid which may change its course and eventually collide with Earth. It will plant a radio beacon, which will help track the celestial body and assess the risks it poses.
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Donald Yeomans is head of NASA's Near Earth Object Program. He confirms that Apophis will come close with the Earth's gravitational pull in the year 2029 and if it hits a certain "keyhole" it has a chance of swinging back around and it will head for Earth once again. But Donald Yeomans assures us that the chance of it hitting the Earth even then is still highly unlikely. Russia did their own calculations and they think Yeomans calculations are slightly off and his predictions are extremely premature. Russian scientists think that when Apophis passes the Earth's very strong gravitational pull on April 13, 2029, it will be a bit closer than what was earlier predicted. Passing the Earth that close will change the pathway of the killer asteroid Apophis, making it quite a possibility of it colliding with the Earth.
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