Article Posted on : - May 07, 2012

LONDON (PTI): Planetary scientists have claimed that flinging pebbles at an asteroid could help deflect the Earth-bound rock in space.

It takes surprisingly little force to deflect an asteroid provided it is done several years before the projected impact.

Previous ideas have included landing an engine on the asteroid to push it away from a collision, and using mirrors or lasers to vaporise its surface and provide thrust to shift course.

Now, a team at the University of Strathclyde in Britain has calculated that a 500-kilogramme swarm of fingernail-sized spacecraft would deflect a fast-moving, 250-metre asteroid by 35,000 kms -- enough to avoid a collision, provided the swarm hits eight years before the expected Earth impact.

A swarm could be launched from Earth in a single rocket.

After release, pebbles could harness the thrust provided by reflected sunlight to steer themselves into a tight cloud directed at the asteroid, the New Scientist reported.

Best of all, each pebble would be too small to crack the asteroid into still dangerous pieces, Alison Gibbings and Massimiliano Vasile, who led the team, announced at the Astrobiology Science Conference in Atlanta, Georgia.