Airborne Laser Successfully Tracks, Hits Missile

fructose writes "The Airborne Laser managed to acquire, track, and illuminate a test missile a few days ago. According to the press release, the Boeing plane 'used its infrared sensors to find a target missile launched from San Nicolas Island, Calif ... issued engagement and target location instructions to the beam control/fire control system ... fired its two solid-state illuminator lasers to track the target and ... fired a surrogate high-energy laser at the target, simulating a missile intercept.' The sensors on board the missile confirmed the 'hit.' Michael Rinn, ABL's program director, said, 'Pointing and focusing a laser beam on a target that is rocketing skyward at thousands of miles per hour is no easy task, but the Airborne Laser is uniquely able to do the job.' The next steps will be to test the high-power laser at full strength in flight and do a complete system test later this year. Its success or failure will determine whether the project gets canceled. Looks like the Real Genius fans out there are finally living the dream."

Comments

Re:Just what we need

[ductonius]

Which is generally isn't above the clouds in the stratosphere.

Hopefully they didn't fake it again

[copponex]

http://www.independent.co.uk/news/world/star-wars-fake-fooled-the-world-1461979.html

I see a press release from the people who claim to have pulled it off... which doesn't mean a thing.

Re:Just what we need

[ductonius]

Nothing, in theory. Just like there's nothing in theory that says the rocket can't have a zillion other systems designed to defeat this laser. In practice, however, the answer is weight. A rocket's weight is around 80-90% fuel with payload being from 2-5%. A small increase in payload weight leads to a great increase in the rocket's size and fuel load.

A rocket designer ends up having to make a series of compromises between the strength of the rocket itself, the payload and the range. If you want to protect your rocket you're going to have to give up payload, give up range or increase rocket size, all of which make them less useful as weapons.

Re:Just what we need

[geckipede]

Changing the output frequency of a giant high energy chemical laser is extremely tricky. Frequency doubling demands a very pure coherence to get good efficiency, and even then "good" in this context means above 50% power converted to the new frequency. With a weapons laser, you're going to have a hell of a cooling problem in the converting medium. Then again, if reflective anti-laser coatings become common, it shouldn't be too difficult to add on a free electron laser system to burn off the mirror layer before the main beam strikes. A free electron laser can change operating frequencies trivially, just by adjusting its internal magnetic field.

Re:How does it aim?

[j. andrew rogers]

Not only mirrors (that occurred to me as well), but have the missile spin so the energy of the laser is spread out over a much larger surface. Spinning would also allow the areas of the missile to cool down somewhat.

All of the "obvious" solutions like you mention generally will not work. The power levels for the lasers are specifically designed to defeat the known technical counter-measures available to a missile designer. This is why laser weapons have a power rating orders of magnitude greater than is strictly required in most conventional circumstances; they are obviating counter-measures before anyone tries to develop them. Among other things, they are designed to ablate the target faster than you can reflect it or physically spin it.

This is also the reason a lot of US military research focuses on hyper-kinetic weapons these days; good ones can defeat all plausible molecular armor and even weak ones can defeat all current armor. The power levels of US weapon systems are getting to the point where any passive counter-measure would have to be very exotic.

In all military advances in offense, the defense will find a way around it (and vice-versa). It's a cat and mouse game. Look at how Iraq tried to foil GPS guided ordinance, they jammed the GPS signals. I don't know how successful they were but given time they might have been successful.

This is based on a media-created myth. The US has never had GPS-guided weaponry, precisely because GPS can be jammed. Therefore, it would not have done much good to have a GPS jammer beyond attracting the attention of missiles designed to destroy RF emitters.

The primary guidance mechanism usually mislabeled as "GPS guided" is ultra-precise inertial guidance, which can't be jammed at all short of altering the physics of the universe. These inertial guidance systems can optionally accept micro-corrections from a GPS input, but only within the (classified) error bounds of the inertial system which are already known to be very small. If the GPS signal deviates from the inertial guidance, the GPS is assumed to be compromised and ignored.

The "GPS-guided weapon" thing is one of many myths about US weapon systems perpetuated by the media. The US never has and never will produce a GPS-guided weapon.