Scottish engineers have come up with a new way of dealing with asteroids that threaten the Earth - firing lasers at them from a swarm of small satellites flying in formation.
"The use of high power lasers in space for civil and commercial applications is in its infancy and one of the main challenges is to have high power, high efficiency and high beam quality all at the same time," says Dr Massimiliano Vasile of the University of Strathclyde.
"The additional problem with asteroid deflection is that when the laser begins to break down the surface of the object, the plume of gas and debris impinges the spacecraft and contaminates the laser. However, our laboratory tests have proven that the level of contamination is less than expected and the laser could continue to function for longer than anticipated."
A century ago, the Tunguska meteorite showed just how much damage can be caused by an impact, with an object believed to be 30-50 metres in diameter devastating a 2000-kilometer area when it exploded in the atmosphere.
"The Tunguska class of events are expected to occur within a period of a few centuries. Smaller asteroids collide with Earth more frequently and generally burn in the atmosphere although some of them reach the ground or explode at low altitude potentially causing damage to buildings and people," says Vasile.
"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."
The system is scalable, so that more satellites could be added for a larger threat, and intrinsically redundant, so that if one spacecraft fails the others can continue.
The same technique, says Dr Vasile, could be used to clear upspace debris, lowering the junk's original orbit to reduce congestion.
"A major advantage of using our technique is that the laser does not have to be fired from the ground," he says.
"Obviously there are severe restrictions with that process as it has to travel through the atmosphere, has a constrained range of action and can hit the debris only for short arcs."