Asteroid airbursts pose a greater-than-expected threat, cautions one impact expert, who calls for a new space warning scale.
An asteroid bursting apart in midair over a city poses a greater threat to humanity than a long-feared "planet buster" smacking into Earth, suggests one impact expert. He calls for a revised system of planetary defense focused on detecting smaller asteroids, instead of the big ones.
Earth orbits amid a shooting gallery of meteorites and asteroids; such shooting stars can be seen crossing the sky every 15 minutes on a typical night.
Sometimes those space visitors are larger, such as the February 15 fireball that exploded over Chelyabinsk, Russia, injuring some 1,500 people in six cities across the region, or the 1908 Tunguska event that flattened 830 square miles (2,150 square kilometers) of Siberian forest.
"The chances are virtually certain that we are going to be next hit by a little asteroid that is a 'city buster,' long before we are hit by a bigger one," said physicist Mark Boslough of Sandia National Laboratories in Albuquerque, New Mexico.
In an upcoming report in the Acta Astronautica journal, Boslough proposes a new "airbust" warning system for asteroids that blow apart in midair rather than blasting big holes in the ground.
"We really need to come up with a way to warn people," he said.