A near-Earth asteroid named Apophis will pass by on April 13, 2029. There's a 1 in 5,500 chance that the asteroid will thread itself through through a 600 meter wide "keyhole" of possible paths, in which case the Earth's gravity alters the asteroid's orbit just enough for it to collide with Earth in 2036. Apophis, discovered last June, is 390 meters (1,280 foot) wide. An impact would release a blast with 100,000 times the energy of the Hiroshima bomb.
The European Space Agency is fiddling with something called the "Don Quixote" mission. A satellite called Hidalgo will charge into an asteroid like Quixote at his windmill. A second satellite--friend Sancho of course!-- will measure any change that Hidalgo made in the asteroid's orbit.
Absolutely no one thinks it's a good idea to use explosives on a near-earth asteroid. Explosions cause fragments. Fragments mean even more of a chance of being hit by something. (Don't anybody tell the Texans; they like blowing shit up. And have you ever seen a Hoosier in a fireworks shop? Of course, Michigan-- we gave the nation Tim McVeigh and Andrew Kehoe the Bath city bomber -- has no right to throw stones.)
What was Hollywood thinking when it sent bombs to blow up asteroids in "Meteor", "Deep Impact", "Armageddon"? Oh, yeah, Hollywood and "thinking"-- I must be sleepier than I thought. (Isn't it kind of weird how B-movies now have A-movie budgets, but without a corresponding improvement in their scripts?)
Twenty years of plannng is a lot to ask from the short-attention span generation. Having grown up on Heinlein novels, I'm confident that human engineers could slap an asteroid away, but are humans politically capable of focusing our attention for such a project? "Depend on it, Sir," Dr. Johnson reassures me, "when a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully."
Short attention span: that's what we get for being primates. The Chinese call the monkey "the animal with a hundred hands", because he can never concentrate... what was I saying? Kipling has the last word on human and monkey society in "Road Song of the Bandar Log"from "The Jungle Books". Brother, Thy tail hangs down behind!
If we had descended from rodents-- the relentless squirrel, the busy beaver-- or even lagomorphs, as any owner of a "never give up" house rabbit will tell you-- I would be a lot less worried about humanity's future.