On Oct 8 an asteroid approximately 10m across entered the atmosphere undetected and exploded with the force of three Hiroshimas 15-20km above Indonesia. The blast registered internationally on equipment designed to detect nuclear explosions.
A significant number of space objects less than 100m in diameter remain uncatalogued. Under legislation passed in 2008 the US Office of Science and Technology Policy must come up with a policy on asteroids by this time next year.
"If you want to find the smallest objects you have to build more, larger telescopes. A survey that finds all of the 20-metre objects will cost probably multiple billions of dollars," said director of the Minor Planet Center in Cambridge, Tim Spahr.