The Earth has experienced a greater number of large-scale impacts from asteroids during the past decade than previously believed -- perhaps as many as ten times the number thought, three former NASA astronauts say.

Ed Lu -- physicist, former U.S. astronaut and head of the asteroid-hunting B612 Foundation -- says 26 explosions releasing atom-bomb levels of energy have occurred around the globe in remote locations since 2001, as detected by a network meant to warn of illegal nuclear testing.

"This network has detected 26 multi-kiloton explosions since 2001, all of which are due to asteroid impacts," Lu said on the foundation's website. "It shows that asteroid impacts are NOT rare -- but actually 3-10 times more common than we previously thought."

Lu and fellow former astronauts Bill Anders and Tom Jones say they'll make a presentation on Earth Day, April 22, of data from the network they say is evidence of impacts far from population centers, suggesting that so far "the only thing preventing a catastrophe from a 'city-killer' sized asteroid is blind luck."

Lu, Jones and Anders are pushing for construction of an asteroid warning system built around a proposed Sentinel Infrared Space Telescope.

When launched in 2018 aboard a SpaceX Falcon 9 rocket, the privately-funded telescope would scan the sky at infrared wavelengths to analyze the velocity and trajectory of asteroids of 500 feet diameter or larger, they say.

From an orbit around the sun closer to our star than that of Earth, it will turn its gaze out into the solar system to detect many thousands of near-Earth cosmic objects as yet undiscovered and unidentified, they say.

NASA set up a Near-Earth Object Program Office in 1998, with the mandate to detect asteroids and comets that could present a potential hazard to Earth.

In March of this year the space agency issued a call to scientists seeking the development of asteroid-detecting computer algorithms.

Asteroids -- and their potential risk to the Earth through impacts -- were firmly placed in the public consciousness in February 2013 when one entered the Earth's atmosphere at more than 40,000 mph and exploded in an air burst high over the city of Chelyabinsk in Russia's southern Ural region.

Undetected until it entered our atmosphere, it liberated energy 20 to 30 times that of the atom bomb dropped on Hiroshima, shattering windows and injuring around 1,500 Chelyabinsk residents, most of whom were hurt by flying glass.

TAG Asteroid, Asteroids, Disaster, space

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