Laser-equipped satellite flotilla could defend Earth from asteroids

Engineers at the University of Strathclyde in Glasgow think they have the perfect plan to deflect Earth-bound asteroids. They want to build a flock of tiny satellites that can fly in formation and fire solar-powered lasers at the giant rock.
So why not just send up one spacecraft carrying a gigantic laser or a massive atomic bomb or Bruce Willis? Lead researcher Massimiliano Vasile says "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."
That last point is important, because when the laser begins to break down the surface of an object, the plume of gas and debris can mess up the spacecraft and contaminate the laser. Though, Vasile does say that "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".
The biggest problem -- which faces both a horde of tiny lasers and a single multi-megawatt laser cannon -- is that high-powered lasers in space are still in their infancy. "One of the main challenges is to have high power, high efficiency and high beam quality all at the same time," Vasile says.
He, and other researchers, have about two decades years to sort that out. Asteroid 99942 Apophis is to make an uncomfortably close call with Earth in 2029, then swing back around for another flyby on 13 April 2036. Nasa has put the odds of Apophis hitting Earth at 1 in 250,000.
The research at Strathclyde won't be wasted, though, if 99942 isn't on a collision course with our planet. The team is now investigating the use of the same concept to remove space debris. The tiny laser flocks could chew up bits of junk, shove others into safer orbits and generally reduce congestion in space.
"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," says Vasile.
Nasa says, "more than 21,000 orbital debris larger than 10 cm are known to exist. The estimated population of particles between 1 and 10 cm in diameter is approximately 500,000. The number of particles smaller than 1 cm exceeds 100 million."

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