A collision between Earth and an asteroid a few kilometers in diameter would release as much energy as the simultaneous detonation of several million nuclear bombs, and with the impact of an asteroid estimated at around 10 km (6.2 miles) in diameter believed to be responsible for wiping out the dinosaurs, numerous strategies have been devised to try and avoid such devastation. The latest idea comes from engineers at Glasgow’s University of Strathclyde who suggest that a swarm of laser-wielding satellites could nudge Earth-bound asteroids off their collision course.

While an Armageddon-style detonation of a nuclear device embedded within an asteroid is fine for the plot of a science fiction movie, many scientists believe a more subtle approach that involves deflecting an asteroid off its course rather than blasting it into radioactive bits and pieces that would rain down on Earth is a preferable and more realistic option. One proposed deflection technique involves using lasers to pulverize the surface of the asteroid, ejecting tiny bits of rock that would act as a propellant and push it onto a different course.

Because a ground-fired laser would have to first have to travel through the atmosphere and would only have limited windows in which to hit the asteroid, some have suggested firing a powerful laser from a single large spacecraft. But the University of Strathclyde engineers believe a fleet of small satellites fitted with solar-powered lasers that would be cooperatively fired at close range would be a better option.

While it was initially feared that the plume of gas a debris that results when the laser breaks down the surface of an asteroid would impinge the spacecraft and contaminate the laser to reduce its effectiveness, Dr Massimiliano Vasile, of Strathclyde’s Department of Mechanical and Aerospace Engineering, says laboratory tests have shown that the level of contamination is lower than expected, allowing the laser to function for longer than first thought.

“We could reduce the threat posed by the potential collision with small to medium size objects using a flotilla of small agile spacecraft each equipped with a highly efficient laser which is much more feasible than a single large spacecraft carrying a multi mega watt,” said Dr Vasile. “Our system is scalable, a larger asteroid would require adding one or more spacecraft to the flotilla, and intrinsically redundant - if one spacecraft fails the others can continue.”

Dr Vasile and his team are also investigating whether the concept of a flotilla of satellites could also be used to remove space debris.