The phrase "asteroid strike" refers to the collision of an asteroid (a large rock in outer space) with another object, usually a planet or moon. Full definition
A major asteroid strike on the planet could cause widespread devastation. (aerospace.org)
After all if cost is no barrier when it comes to dealing with hypothetical threats like global warming it should be no barrier when it comes to hypothetical threats like asteroid strikes. (dotearth.blogs.nytimes.com)
A large asteroid strike happens only once every 100 million years. (washingtonpost.com)