posted on Sep, 28 2006 @ 10:05 AM
I can actually speak with a tad bit of authority on this subject, as I attended an IEEE conference where one of the tracks was a whole lecture on the
use of HEW weapons, and I can say with 99% certainty that High Energy Weapons of any sort, including "laser beams" are impractical across that
distance. Here's why: HEWs heat, not cut or bore. - Lasers, as weapons, are not intended to cut through objects, bore through them, or anything of the sort.
Their purpose is to heat up the target to the point where its operation thermal threshold is exceeded and the device is thusly disabled.
Cannot track well through atmospheric particles - Despite how clear or stable the air appears to be, it is, in fact, exponentially
detrimental to tracking with a laser. As we are all well aware, a laser is composed of highly concentrated photons. Over short distances, the sheer
volume of photons are able to mostly burn through the dust and vapor floating in the air. However, it is important to note that some photons are
deflected when this happens, their trajectory might change as subly as a fraction of a degree, or as much as 180 degrees, depending on the angle of
incidence (the angle the photon strikes relative to the surface of the particle it hits) and the ablation (reflectiveness) of the particle. The
important thing to remember is that particles floating in the air are MUCH more massive than photons.
The effect would be akin to throwing a rock at the side of a building. Now, if you had billions of little rocks, equal to the volume of, say, a
stadium, and were able to forcefully project them at a building the size of a house, you would still end up destroying the house and sending a LOT of
rocks out the other side, in roughly the same direction, but a portion of the rocks would be lost during impact, or deflected, leaving fewer rocks
most likely travelling at a different angle.
This is one of the reasons when you shine a beam of light (like a flashlight), the light spreads out further and weaker the longer the distance. A
laser is little more than a very very powerful concentrated flashlight, and is thus susceptible to the same trajectory-altering physics.
The end result is that prolongued laser exposure to surface will "dance" at the impact point in a random fashion. The more atmosphere it is beamed
through, the larger the dance will be on the target. As of about two years ago, the best they managed was a two-foot radius dance at a littler under
40,000 feet with two stationary targets, over the course of 30 seconds. It was not a solid dot that slid around the radius, but rather a jumping dot
that sometimes disappeared altogether. For a satellite to remain in orbit, the distance to Earth's surface must be at least 35,768 km, most are
around 45,000 km.
That means over 117,349,081 feet of atmosphere must be passed through. Using only simple math, that equates to a "dance" of 5867 foot radius. Since
the effect is actually exponential, it is unlikely to be that small in reality.
With only a two-foot dance, there is still not enough continuous contact to generate enough heat to disable craft at only 40k feet, within Earth's
comparatively thick atmosphere and hotter temperature, much less the much colder depths of space where there is no air insulation to trap heat.
So effectively to disable a satellite with a HEW, you would have to overcome the random particulates and airflow through the atmosphere, and to do
that, you've either got to be in space, or somehow create a vacuum between your laser and the target for the length of the heating.