Space agency describes the scenario as 'low probability but high consequence', meaning it will probably never happen, but if it does we're toast Among Earth's natural disasters - hurricanes, floods, earthquakes - the one humans probably ponder least is asteroids, huge objects zipping through our solar system at ludicrous speeds. Federal officials call an asteroid or comet collision "low probability but high consequence", Nasa-speak for it will probably never happen, but if it does we're toast.