Chicken Little, we owe you an apology. New scientific research confirms that the sky is falling more often than we would like hear. It’s high time to do something about it.
Last February a chunk of the sky, or more accurately a 60-foot-wide chunk of rock falling from the sky, exploded at a height of about 18 miles above the Russian town of Chelyabinsk with the force of 30 Hiroshima-sized atomic bombs. Its shock waves shattered windows and injured more than 1,000 people. If it had exploded at a lower altitude, the damage would have been far more extensive, including major loss of life.
The explosion drew needed attention to the risk from small space objects.
In recent years NASA has funded studies of near earth objects (NEOs) that might pose a threat to life on earth.
About 90 percent of the NEOs with diameters of 1,000 meters and above — ones that could destroy life on earth — have been mapped, and progress is being made in documenting almost as dangerous objects half that size.
But there is no good inventory of potential city-busting asteroids like the one that exploded in February. The meteor that flattened 800 square miles of Siberian forest in a tremendous explosion in 1908 was also small, probably not more than between two and three times as wide as the Chelyabinsk rock. Telescope surveys have estimated that there are three to four million city-busting rocks whizzing through space near Earth. But new studies suggest that the number could be far larger.
This sort of asteroid strike has been considered a rare event occurring perhaps once or twice a century.
But a new study recently published in Nature magazine used data collected by the U.S. government to estimate that city-busters hit earth every 10 to 20 years. It put the risk of collision as much as 10 times greater than previously thought.
“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,” physicist Mark Boslough of Sandia National Laboratories in Albuquerque, N.M., told National Geographic magazine earlier this year.
The data are not conclusive, and there is a wide range of uncertainty. But the possibility that a meteor might explode above a large city can now be seen as a risk of roughly the same order of magnitude as hurricanes, tornadoes, earthquakes and similar natural disasters.
This calls for stepping up efforts to map city-busting meteors that cross Earth’s orbit, identify ones that are threats, find ways of deflecting them from Earth’s path, provide early warning of unavoidable collisions and make preparations for dealing with their consequences.
Or we could all go into Foxy Loxy’s cave and try to forget about it.