Interest continues to grow. Thank you, Samwise, for including this little blog on your roll. As you would say, "There's some good left in this world, and it's worth fighting for!" Thanks also to Mixed States and Megite Science News for adding to your feed.
Thanks to Astroprof too. This week his interest in asteroids coincides with mine. Asteroid 99942 Apophis was only discovered in 2004. On April 13, 2029 Apophis will pass extremely close to Earth, lower than our communications satellites. In 2036 it will come by again. There is a danger, but this is also an opportunity for a spacecraft rendezvous.
We can only compute probabilities whether an asteroid will strike the Earth. Recently I have been assigned to track asteroids, and it is a tricky business. Usually they are just streaks on a photographic exposure, subject to all the vagaries of atmospheric distortion. I've computed Apophis' position on November 2, 2012 when it will pass between Earth and the Sun. Projecting this orbit further into the future eats up more computer time and introduces more uncertainties
One solution is to follow an asteroid the way they we track aircraft, with a transponder. Currently NASA lacks the budget to land something on Apophis, but the Planetary Society is soliciting proposals. The Orion CEV should be in full operation before 2029; someone should consider a crewed mission. We may not land on Mars by then, but Apophis is a target which may someday touch our lives.