How NASA proposes to deflect `killer` asteroids endangering Earth

Washington: What if an asteroid were headed straight for Earth?Well, NASA evidently has us covered. In 2005, in a bill authorizing space-program funds, Congress asked NASA for a plan to identify, track and deflect - yes, deflect - all manner of PHOs (potentially harmful objects) that could pose a threat, ABC News reported.

The directive, according to NASA, is known as the George E. Brown Jr. Near-Earth Object Survey Act, named after the late Democratic chairman of the Committee on Science, Space and Technology, who died in 1999 and didn`t live to see NASA`s asteroid plan on paper. Rep. Dana Rohrabacher, R-Calif., successfully included it in the 2005 bill. With that congressional prompt, NASA considered many science-reality options, including some that bore resemblance to film plots. Among the solutions NASA studied were firing a nuclear missile at the asteroid, landing a nuclear bomb on the surface, drilling into the great space rock and exploding a nuclear bomb there (which Bruce Willis attempted to do in the film, "Armageddon"), and all those same strategies with conventional bombs. The scientists also gamed out some weirder possibilities designed with more warning time in mind. Those included flying a spacecraft near the asteroid for a long time to act as a "gravity tractor" and pull it off course (deemed ineffective, unsurprisingly); using a large mirror to focus sunlight and "boil off" some material from the asteroid; a spacecraft "rendezvous" with the asteroid to "boil off" some material using a "pulse laser"; landing on the asteroid, drilling into it, and "eject[ing] material from PHO at high velocity"; "attach[ing]" a spacecraft to the asteroid and pushing it out of the way; and what NASA called the "Enhanced Yarkovsky Effect" - altering the reflectiveness of a rotating asteroid and counting on the "radiation from sunheated material" to push the asteroid off course. The winner: nuclear bomb. For a fast-approaching comet, the only recourse may be drilling into it and detonating a nuclear bomb . But, in general, NASA favored simply firing a missile at a space rock and detonating it nearby. Landing on the asteroid, or drilling into it, would make for a better explosion, but NASA was wary of fragmenting the big rock. Unfortunately, nuclear explosions in space are banned under a 1967 UN space treaty, so other nations would have to sign off on the plan. ANI