March 1, 2003 :: Popular Science :: News
Popular Science magazine presents an inside-look at the Air-Borne Laser missile defense system.
Here’s how it will happen: Six infrared sensors positioned on the fuselage will constantly scan all directions for hot missile exhaust plumes, which they can do autonomously or at the prompt of launch-detecting satellites. When one, or several, is located, the ABL’s multiple separate lasers will swing into action—-all within seconds. A laser ranging pod atop the plane’s cockpit, right now almost four stories above us as we stand on the ground, will spin around to face the first missile—-the one the computer has determined is most threatening —-and measure its distance with a carbon dioxide laser. The track illuminator laser, fired through the 12-inch aperture of the Wall of Fire and into the nose turret, will compensate for aircraft vibration and then pinpoint a specific area of the missile to aim at. The beacon illuminator laser, also fired through the nose turret, where a cassegrain reflector telescope expands the beam’s dimensions to 1.5 meters, will then use the beam-and fire- control unit’s adaptive optics to characterize the missile’s dimensions. (These optics, standard equipment on all the ABL’s turret-fired lasers, extend their range with mirror-flexing technology to compensate for atmospheric turbulence.) Finally, the computer will fire the high-energy laser, which will focus down from 1.5 meters in diameter to a much smaller spot of light by the time it reaches the target. As the laser dwells on the missile’s flank for 2 or 3 seconds, the oxidizer or fuel tank will rupture and the missile will explode.
The article quotes Ted Postel, longtime opponent of missile defenses, with some interesting observations about the ABL:
Others think the laser itself will work but could fail in its prime mission; in other words, that the ABL may be better suited for attacking long-range intercontinental ballistic missiles and satellites than short-range weapons that operate within relatively compact geographic areas. “Theater ballistic missiles have shorter-powered flight time at lower altitudes where the atmosphere is denser,” says Ted Postol, a professor of science, technology and national security policy at the Massachusetts Institute of Technology. “Going against an ICBM would be easier because the missile undergoes longer-powered flight, and the intercept would occur in less atmosphere.”
Postel’s observation is interesting for the following reason: he points out the weaknesses of the ABL—incidentally begun under the Clinton administration as an excuse for not doing more serious missile defenses—and in so doing makes the case for other systems which would be more effective. Longer range ICBMs are indeed more vulnerable than shorter theater ballistic missiles, but for this very reason a space based laser would make additional sense.
(Article)
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