Stardate 20010722.0845 (On Screen): Within two years they intend to do a test where a 10 megawatt laser mounted in a 747 shoots down a SCUD-equivalent missile. Unlike the fantasy son-of-SDI our President is pushing, this is completely plausible. It is not, however, capable of being used as a strategic defense; it's being developed as a theater defense weapon such as the Patriot was claimed to be (though it actually was nearly ineffective) during the Gulf War.
These lasers don't operate from an electric power source; rather, they're using chemical operations (read "flames") to create an energetic burst of light which may only last a second or two. The weapon system would have a limited amount of fuel and thus a limited number of shots, but it could potentially be immense (several hundred) on a jet that large. What I can't figure out is how they're going to aim it. They can't possibly aim it by laying the jet itself; there's no way that could be accurate or responsive enough. Clearly there must be some sort of optics involved. If so, it's going to be replace-per-use; I don't believe anyone can create any kind of optics, glass or mirrors, capable of handling those kinds of power levels without being ruined after one shot (or even part way through the shot). The only other possibility is that they are actually swiveling the entire laser. If so, that's going to be an impressive servo. To hit a 2 meter wide missile at a range of 50 kilometers, you'd need to lay the weapon accurate to about 1/1000th of a degree. It's really hard to do that rapidly when moving a large mass; that laser may weigh a ton and the servo will need to be able to handle at least a ten degree field of fire off the heading of the jet, and they've got to lay and fire in about ten seconds or they'll miss their chance. (discuss)
Update: The inevitable hype: "Retrofitting the jumbo jet to house the giant laser, he noted, is the largest aircraft modification project Boeing has undertaken." I'd venture to say that this is easy compared to modifying a 747 to carry a Space Shuttle on its back.
