LONDON â€" The spectacular meteorite shower that blasted Siberia early Friday somewhat stole the thunder of another chunk of space rock that was due to stream past Earth later in the day.
In the closest encounter ever recorded with a large space object, the 150-feet diameter asteroid 2012 DA14 was on course to come within 17,200 miles of the Earth at 2:24 p.m. E.S.T.
In cosmological terms, that counts as a near miss, although scientists have issued reassuring statements that there is no need to panic.
The meteorite shower that struck Russia’s Chelyabinsk region, reportedly injuring more than 400 people, was nevertheless a reminder that danger can come literally out of the blue.
It rased the question whether the world is prepared to avert the threat of a potentially much bigger disaster from a collision with a near-Earth object.
Scientists have warned that greater international cooperation is needed if humanity is to avoid the fate of the dinosaurs, believed to have been wiped out after an asteroid struck what is now Mexico 66 million years ago.
Space-watchers are already keeping a close eye on 1999 RQ36, a 1,837-feet giant that has a one in a thousand chance of hitting Earth on its next close encounter in 2182.
It is one of 1,300 space rocks on NASA’s list of “potentially hazardous asteroids.†The U.S. space agency plans to launch an unmanned mission in 2016 to bring back rock samples from the asteroid and measure the forces acting on it.
“Anything ov! er a few hundred yards across that appears to be on a collision course with Earth is very worrisome,†according to Edward Beshore, a University of Arizona scientist involved in the mission.
Research has focused on how to divert potentially Earth-bound space rocks with a variety of technologies that range from attaching them to space-borne versions of a ball and chain to blasting them with a nuclear bomb.
But first you have to find them.
The asteroid 2012 DA14, which was near enough to be visible from Earth on Friday during its 4.9 miles-per-second fly-by, was first spotted only in February 2012 by a Spanish dentist.
According to asteroid-hunting scientists at the B612 Foundation, who include NASA veterans, Friday’s close encounter amounts to a wake-up call from space.
“Of the million asteroids as large as or larger than 2012 DA14, we have only tracked less than 10,000,†it said in a posting on its Web site.
“So the fact that we knew ahead of time that 2012 DA14 is about to buzz by Earth is really only a matter of luck,†it wrote. “Ninety nine percent of the time we are oblivious, simply because we have not mapped and tracked 99 percent of Near Earth Asteroids.â€
In 2008, space experts from the Association of Space Explorers called for a coordinated international action plan, under the umbrella of the United Nations, to counter the asteroid threat.
Its proposals included mounting an international mission to practice diverting a small, harmless space rock, as well as launching a global scientific debate on how best to deflect a! n asteroi! d (and who would pay for it.)
Like the script of a science fiction movie, it evokes the prospect of disparate nations coming together to counter a common extraterrestrial threat.
As Dmitry Rogozin, the Russian deputy prime minister, said on Friday, the Siberian meteorite strike showed the need for an international initiative to create a warning system for “objects of an alien origin.â€
