I wouldn't bet on us noticing the meteor sufficiently early for an evacuation. We have mapped only a tiny portion of asteroids in our solar system and, iirc, the budget for that program keeps getting cut.
Luckily, there are new companies springing up to do work like this because it will be profitable some day. Planetary Resources is specifically looking for big rocks to do mining operations on, but is taking it into their own hands to map for unknown objects with Near Earth trajectories. That doesn't take away from how sad it is that our governments have cut the already-small budgets of important research like this. That's a crime, really.
Edit: here's the startup pitch I added to our last YC application in the "other ideas" section (I wonder why it didn't get funded):
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4) Planetary defense network to protect from asteroid impact. Build small satellites to search for and redirect dangerous asteroids. Rather than last-minute warning systems or explosion/impact-based protection, it would work by slowly gravitationally changing dangerous asteroid orbits so that they will not hit Earth. Build it so that it’s gravitationally self-sufficient and can use captured asteroids to deflect incoming dangers. This is similar to the recent work at Planetary Resources in Seattle - while they prospect for minerals we would direct asteroid orbits. In February of 2016, NASA announced the creation of the Planetary Defense Office to coordinate these efforts globally. Now is the right time to start working on this.
Perhaps I haven't explained my idea very well. I'm imagining millions of small robotic spacecraft, self-constructed by self-mining asteroids that they have found on their own. The little asteroid spacecraft would roam the solar system on huge orbits and search for potential Earth impact-bound objects. If it finds something, over the course of hundreds of years, or thousands of years, the network of small asteroid spaceships could send a probe to the offending target and adjust its orbit so as not to impact. It could then use the offending targets to create new nodes in the system. Theoretically the defense network could last as long as the sun does.
I do agree that the law of unintended consequences might mean that building such a system would instead ensure the destruction of the Earth rather than save it. But it's an idea.
That's a fun idea, and obviously a long way out, but there would have to be a lot of advances to make it possible.
Not all asteroids are made of the same stuff, so the robots would have to know many possible materials that the robots could be made of and how to process the raw materials into those refined materials and how to actually build the equipment to do that refining. That means that they would also have to know many ways to build refining equipment depending on what materials are available. It's a lot of variables and very difficult.
For instance, how can they create circuit boards if silicon and carbon and copper aren't available?
I think it makes more sense to build a robot factory in one location (a low gravity moon for instance) and send out the first few thousand robots to known asteroids. They could attach and shift orbits to where they crash on the other side of that moon where robots go and harvest raw materials to bring back to the factory.
Your current proposal is like telling 100 people to go to 100 specific locations on earth and build a bicycle with what is at that location. One guy in the desert might end up with a bike made of glass fired from the sand. Someone in the jungle might end up with one made with ivy and bamboo. While it's theoretically possible, it would be easier to send them out and tell all 100 to bring back all the materials they find to a central location and build bicycles out of the pile of stuff. The large amount of materials would render bicycles that are made of the best possible materials for each part.
P.S. If you're working at a startup that's pitching long-shot ideas like this, I really want to join you guys!
But those efforts are mostly focused on the big asteroids that wipe out huge areas, right? Spotting an asteroid the size of a minivan or so is really hard, but if something of that size hits a city, thousands die.
> Spotting an asteroid the size of a minivan or so is really hard
Its really not; as I understand, our current technology is sufficient to find things much smaller than that at the distance of the inner edge of the Kuiper Belt.
The problem, at any size, is that we scan very little of the sky, not that its hard to find objects of any size that would be dangerous.
