Astronomers don't know anything about many near-Earth asteroids that are 20 times larger and radically heavier than this week's visitor. Any of these up to 1 km rocks could be civilization-ending.
A spokesperson at the University of Kent reported that they were far from having the problem covered. Some help is potentially at hand - the dedicated Asteroid Terrestrial-impact Last Alert System or Atlas, designed to give at least a few days' notice of impending asteroids by scanning the whole sky every night. Also, amateur asteroid enthusiasts share vital information. But the problem remains. We could be taken unaware by a completely unknown asteroid at any time.