A swarm of small satellite-operated lasers could deflect asteroids headed for a catastrophic collision with Earth, a discovery that could radically change asteroid deflection technology. Researchers at the University of Strathclyde are floating the possibility that a group of small satellites could fly in formation and cooperatively fire solar-powered lasers at a threatening asteroid. The discovery would overcome difficulties associated with current methods, which focus on large unwieldy spacecraft. “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,” said Dr. Massimiliano Vasile of Strathclyde’s department of mechanical and aerospace engineering. “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,” Vasile said. “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.” Researcher Alison Gibbings with Dr. Vasile. (Image: University of Strathclyde) More than 100 years ago, a Tunguska meteorite demonstrated just how much damage could be caused by an impact. The object, believed to be 30 to 50 m in diameter, devastated a 2000-km area of vegetation when it exploded in the atmosphere. Although the likelihood of an immediate threat from a similar asteroid strike is low, it has been recognized that researching preventive measures is significant. “The Tunguska class of events are expected to occur within a period of a few centuries,” Vasile said. “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. “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 multimegawatt.” The system is scalable, so that more satellites could be added for larger asteroids, and intrinsically redundant, so that if one spacecraft fails, the others can continue. In addition, the laser does not have to be fired from the ground. “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,” Vasile said. Vasile is now investigating whether the same concept could be used to remove space debris. The space-borne lasers could be used to lower the original orbit of debris and reduce congestion. “The amount of debris in orbit is such that we might experience a so-called Kessler syndrome — this is when the density becomes so high that collisions between objects could cause an exponentially increasing cascade of other collisions,” Vasile said. “While there is significant monitoring in place to keep track of these objects, there is no specific system in place to remove them, and our research could be a possible solution.” The research was presented in February to the Planetary Society. For more information, visit: www.strath.ac.uk