On 15 February, an 11,000-tonne space rock slammed into the atmosphere above Russia, producing the most powerful impact since the Tunguska explosion in 1908 - which may also have been caused by an asteroid - and generating a shock wave that damaged buildings and injured more than 1,000 people. The 18-metre-wide object could not be seen as it approached the planet because it was obscured by the Sun's glare, but observations made while it was in the atmosphere have enabled several groups of researchers to estimate its orbit.
However, the estimates varied so much that there was no clear orbit that researchers could use to hunt for sibling asteroids on a similar path, say Carlos and Raúl de la Fuente Marcos, orbital dynamicist brothers at the Complutense University of Madrid.
They decided to tackle the problem with brute computational force, running simulations of billions of possible orbits to find the ones most likely to have led to a collision. They then used the average of the ten best orbits to search a NASA asteroid catalogue for known objects on similar paths. They found about 20, ranging in size from 5 to 200 metres across, they report in an article to be published in Monthly Notices of the Royal Astronomical Society: Letters.
