There is a more recent post from Leonid Elenin with updated data: http://spaceobs.org/en/tag/c2013-a1-siding-spring/ http://spaceobs.org/en/tag/c2013-a1-siding-

There is a more recent post from Leonid Elenin with updated data: http://spaceobs.org/en/tag/c2013-a1-siding-spring/ http://spaceobs.org/en/tag/c2013-a1-siding-spring/ "the comet might pass just 41,000 km [...] from the planet’s centre [...] 100% certainty that the planet will pass through the gaseous envelope of the comet [...] will be subject to intensive bombardments by microparticles which, among other things, might cause malfunction of the space probes currently there."