Risk of ‘city-killing’ asteroid striking Earth higher than thought, experts warn

California-based B612 Foundation building asteroid-detecting telescope to raise awareness of threat from space

PUBLISHED : Wednesday, 23 April, 2014, 10:20am
UPDATED : Thursday, 24 April, 2014, 2:14am

The chance of a city-killing asteroid striking Earth is higher than scientists previously believed, a non-profit group building an asteroid-hunting telescope said on Tuesday.

A global network that listens for nuclear weapons detonations detected 26 asteroids that exploded in Earth’s atmosphere from 2000 to last year, data collected by the Comprehensive Nuclear Test Ban Treaty Organisation shows.

The explosions include the February 15, 2013, impact over Chelyabinsk, Russia, which left more than 1,000 people injured by flying glass and debris.

“There is a popular misconception that asteroid impacts are extraordinarily rare ... that’s incorrect,” said former astronaut Ed Lu, who now heads the California-based B612 Foundation.

The foundation on Tuesday released a video visualisation of the asteroid strikes in an attempt to raise public awareness of the threat.

Asteroids as small as about 40 metres have the potential to level a city, Lu told reporters on a conference call

“Picture a large apartment building – moving at Mach 50,” Lu said.

Mach 50 is 50 times the speed of sound, or roughly 61,250 km/h.

Nasa already has a programme in place that tracks asteroids larger than 1 kilometre. An object of this size, roughly equivalent to a small mountain, would have global consequences if it struck Earth.

An asteroid about 10 kilometres in diameter hit Earth some 65 million years ago, triggering climate changes that are believed to have caused the dinosaurs – and most other life on Earth at the time – to die off.

“Chelyabinsk taught us that asteroids of even 20-metre size can have substantial effect,” Lu said.

City-killer asteroids are forecast to strike about once every 100 years, but the prediction is not based on hard evidence.

B612 intends to address that issue with a privately funded, infrared space telescope called Sentinel that will have the task of finding potentially dangerous asteroids near Earth. The telescope, which will cost about US$250 million, is planned for launch in 2018.

B612 takes its name from the fictional planet in the book The Little Prince,” by French author and aviator Antoine de Saint-Exupery.