A 100-meter rock is headed for Mars. While the orbit is still highly uncertain, the latest estimate is 1 in 75 chance of it impacting on Jan 30th. I can't wait, and (being the mad scientist that I am) hope it happens! We have probes in orbit around Mars that would hopefully be in a position to observe the impact. There is much to learn from it; the global effects of that impact will help us refine our models and perhaps alert those yet unconvinced that Earth may be in line for a similar punishment.