On the morning of February 15, 2013, the sky above Chelyabinsk, Russia, was colored with a long streak of fire. A few moments later the shock wave from the explosion which occurred at an altitude of about 30km reached the surface, causing the explosion of glass and windows and injuring about 1,200 people. It was the unexpected arrival of an asteroid of about 17-20 meters in diameter, which released an energy equal to about 30 times that released by the Hiroshima bomb. Ten years later, many things have changed, as explained by the information service coordinator of ESA’s Near-Earth Object Coordination Center (NEOCC), Juan Cano. “That episode was an alarm bell for all the politicians in the world. Our agency was founded in that same year”, says Cano, who, together with a team of astronomers stationed in Frascati, near Rome, scans the sky and calculates the trajectory of hundreds of thousands of objects orbiting the solar system. “We have found practically all of the biggest objects, the ones on which there is still work to be done are those of reduced dimensions, such as that of Chelyabinks”, explains the astronomer. “The greatest threat – he adds – is represented by objects arriving from the direction of the Sun because telescopes cannot see them”. A demonstration in this sense came just a few days ago, when a fireball observed just 5 hours in advance lit up the night in Paris. For this reason, several new-concept telescopes have been funded in recent years, such as ESA’s Fly Eye which will be installed on the top of Mount Mufara in Sicily. Even the Nasa DART mission and the European HERA mission in recent years have demonstrated the technological ability to intervene in the event of dangerous objects on a collision course with the Earth. “There’s still a lot of work to do, but of all those we’ve found, none have a greater than 1% chance of hitting us,” concludes Cano.
by Francesco Giovannetti