At some point, as has happened in the past, a huge asteroid will be headed for Earth, threatening the planet with indescribable damage. That point could come within days or it could take centuries. And Hollywood theorizing aside, it's not clear what we might do about it.
Last week's meteor over Russia and the larger asteroid later that day spurred the normally laconic House Science committee to action. Newly elected committee chair Rep. Lamar Smith (R-Texas) suggested that the event was "a stark reminder of the need to invest in space science." From a committee statement:
[Smith said:] "Developing technology and research that enable us to track objects like Asteroid 2012 DA14 is critical to our future. We should continue to invest in systems that identify threatening asteroids and develop contingencies, if needed, to change the course of an asteroid headed toward Earth." …
The Science, Space, and Technology Committee will hold a hearing in the coming weeks to examine ways to better identify and address asteroids that pose a potential threat to Earth.
It probably goes without saying that this is the same "science" committee that has excelled at downplaying and ignoring the science of another, less science-fictiony threat: climate change.