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MirrorsMirrors is the best way to deflectMiller 07, (New York Times, Lia Miller, 12/9/07, “The Best Way To Deflect an Asteroid”, http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=%22Nancy+Atkinson+is%22#hl=en&authuser=0&q=related:arstechnica.com/science/news/2008/04/how-to-deflect-an-asteroid.ars+deflecting+asteroids&tbo=1&sa=X&ei=KzkBTpHuGsmBtgetqeTtDQ&sqi=2&ved=0CD8QHzAE&bav=on.2,or.r_gc.r_pw.&fp=4afc07978b3d329f&biw=1246&bih=600, SH) In 1908, an asteroid is thought to have entered the earth’s atmosphere and exploded over a Siberian forest, leveling some 800 square miles of trees in what is known as the Tunguska Event. If we knew today that another asteroid were on a path to intersect with our planet, what could we do? Massimiliano Vasile, a lecturer in aerospace engineering at the University of Glasgow, recently concluded a two-year study comparing nine asteroid-deflection methods, rating them for efficiency, complexity and launch readiness. The best method, called “mirror bees,” entails sending a group of small satellites equipped with mirrors 30 to 100 feet wide into space to “swarm” around an asteroid and trail it, Vasile explains. The mirrors would be tilted to reflect sunlight onto the asteroid, vaporizing one spot and releasing a stream of gases that would slowly move it off course. Vasile says this method is especially appealing because it could be scaled easily: 25 to 5,000 satellites could be used, depending on the size of the rock. The losing ideas — satellites equipped with lasers; detonating a nuclear explosion; pushing the asteroid with a spacecraft, to name a few — might still have their place. Vasile says improved technologies could make others appealing in the future. (In March, NASA released a report on “near Earth objects” that deemed the nuclear-explosion method the most effective.) Michael Gaffey, professor of space studies at the University of North Dakota, says the risk of dying from an asteroid strike is about 1 in 2 million. The problem is that the consequences are tremendous; a half-mile-wide asteroid or larger, of which there are more than 700 that come close to Earth’s orbit, could have an impact equal to 60 billion tons of TNT. While it is not likely to happen, you still want to be prepared. “You don’t panic, you don’t have to run around screaming and waving your hands,” Gaffey says. “But you do need to devote resources to it. Mirrors solveEngineer ‘7 (The Engineer, The Big Picture: Mirrored Army to Protect Earth, 10-15, lexis) A fleet of satellites carrying large mirrors, flying in close formation, could save the Earth from a direct hit by an asteroid, according to space scientists at Glasgow University. The 'Mirror Bee' concept is the best method for deflecting asteroids on a collision course with Earth, said Massimiliano Vasile of the university's Space Advanced Research Team (SpaceART). Vasile and his team studied nine methods of deflecting asteroids but the Mirror Bee option appeared most feasible. It uses concave mirrors mounted on satellites to focus the Sun's rays on to the asteroid and heat its surface so it sublimes into a plume of gas, which will create a thrust. A single mirror would be effective, but it would need to be up to 10km across, Vasile said. Using technology from missions involving constellations of satellites, multiple spacecraft could be flown in formation, with smaller mirrors, to focus the sunlight on to a single spot, 1-1.5m across. 'If we have a satellite with a mirror 2m in diameter, we would need 1,000 of them, and they'd have to focus the sunlight for 90 days to deflect an asteroid,' he said. 'But if we go up to 20m, we'd need 10 satellites and 200 days.' Mirrors deflection ideaLamb Nodate, (Robert Lamb is a senior fellow and deputy director of the Program on Crisis, Conflict, and Cooperation (C3) at CSIS, researching governance and development amid conflict, Howstuffworks.com, “TOP 10 WAYS TO STOP AN ASTEROID”, http://dsc.discovery.com/space/top-10/asteroid-stopping-technology/index-03.html, SH) Mirrors work on vampires and gorgons, so why not monstrous asteroids? Brandishing a mirror against an asteroid actually has much more in common with the nuclear option mentioned before. Strategically positioned mirrors could concentrate solar rays, heat a small portion of an asteroid's surface, and cause it to spew vapors. As this material ejects from the asteroid, it would provide a little thrust to alter the space rock's path. Early ideas called for a colossal single space mirror, but modern revisions lean toward a multiple-mirror system to work in unison. Among scientists, the mirror strategy is referred to as laser sublimation. Solvency – Lasers & MirrorsLaser or mirror ablation solvesSchweickart ‘4 (Russell, Chair of the B612 Foundation, former astronaut, Executive Vice President of CTA Commercial Systems, Inc. and Director of Low Earth Orbit (LEO) Systems and research, and scientist at the Experimental Astronomy Laboratory of the Massachusetts Institute of Technology (MIT), “Asteroid Deflection; Hopes and Fears,” Aug., Presented at the World Federation of Scientists Workshop on Planetary Emergencies, Erice, Sicily, August 2004 http://www.b612foundation.org/papers/Asteroid_Deflection.doc) Again, simplifying for brevity, both the laser and mirror ablation concepts utilize high energy electromagnetic radiation to heat a localized portion of the asteroid surface from a station keeping stand-off position either ahead of or behind the asteroid. Vaporizing the surface will generate a small, but potentially significant thrust opposite to the direction of the gases as they escape the asteroid surface. In the case of the laser a very high temperature must be generated to vaporize the surface and the surface must maintain high temperatures despite the fact that the spot is continually moving out of the laser beam due to asteroid rotation. Clearly a pulsed laser system of higher power could be substituted to partially avoid this effect. One challenge for the laser is to maintain a station keeping position with respect to the asteroid for considerable lengths of time while precisely pointing the laser beam. Additionally to provide the very high energy to power the laser will likely require a space nuclear electric system in order to reliably provide the necessary electricity at reasonable launch weight. Finally an intrinsic problem with all the optical ablation concepts is that the ablating gases from the asteroid will gradually tend to coat all optical surfaces and some self-cleaning design may well have to be built in to the design. Mirror ablation is similar in kind to the laser systems with the exception that concentrated and focused sunlight is heating mechanism. While this requires no or little electrical energy to operate the area of the solar collecting concentrator must be very large, probably several square kilometers. Assuming that the deployment and figure control of such a large surface can be successfully addressed both the station keeping, attitude control, and vapor deposition degradation issues are daunting, to understate the challenge. When all is said and done the launch weight of such an alternative will be substantial if not prohibitive. 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