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Using high energy lasers could reduce the cost of shooting down missiles and UAVs, while improving accuracy

The Middle Eastern nation of Israel is currently in the midst of a dire real world test of the most ambitious missile defense system in history -- Iron Dome.  While the system cost billions to deploy, in the recent conflict along the Gaza Strip border it has paid off. The system has intercepted an estimated 80 to 90 percent of missiles that are directed at populated targets (as the enemy's missiles are improvised and hand-launched, many land harmlessly in the desert; the system ignores those marks).

In the U.S., Lockheed Martin Corp. (LMT), one of the world's largest defense contractors, is testing a high-tech missile defense system that could one day replace or supplement missile-based interceptor systems like Iron Dome.

The Lockheed system is dubbed the "Area Defense Anti-Munitions (ADAM) system" and packs a powerful 10-kilowatt laser capable of destroying targets up to 2 km (1.24 mi) away.

In a field test of ADAM, the system "successfully engaged" (sounds like a hit, but not necessarily destruction of) an unmanned aerial vehicle at a distance of 1.5 km (0.9 mi).  The system also "destroyed" not one, but four "small-caliber rocket targets" at a range of 2 km.

Adam UAV target
This is the image seen from the ADAM system as it locks onto the UAV.

Lockheed Martin developed the entire modular software/hardware package that powers targeting and interception.  The system uses radar to locate threats and the built-in laser to eliminate them.

Paul Shattuck, Lockheed Martin’s director of directed energy systems for Strategic and Missile Defense Systems comments, "Lockheed Martin has applied its expertise as a laser weapon system integrator to provide a practical and affordable defense against serious threats to military forces and installations.  In developing the ADAM system, we combined our proven laser beam control architecture with commercial hardware to create a capable, integrated laser weapon system."

Adam wagon
An artist's rendering of the 10 kw laser-based ADAM interceptor system

An important limitation of the system is its line-of-sight (LOS) requirement.  As the destructive force is delivered via a laser light beam, it can only target projectiles it can "see".  This shortcoming may lead traditional interceptors to be used closer to populate regions (where exploding missiles directly overhead could endanger citizens), but supplemented by laser-based interceptor system on the border of a hostile neighbor entity/state.

The capability to intercept UAVs is particularly interesting.  While the U.S. has long had a relative hegemony on the emerging combat technology, which it has fielded in combat operations in Iraq, Pakistan, and Afghanistan, of late several hostile nation-states have been working to develop UAVs of their own.  Most notably Iran, known for voicing strong anti-American, anti-Israeli sentiments, showed off his "Messenger of Death" drone bomber, which it is developing, aided by reverse engineering of a seized U.S. UAV flier.

Source: Lockheed Martin

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RE: Slowly but surly!
By Solandri on 12/1/2012 3:40:19 PM , Rating: 4
In fact, thats the main thing I think we lack between us and the original Enterprise or a Babylon 5 sort of Earth ship; energy so cheap as to be an afterthought. If it weren't so expensive to kick things in to orbit, then everything else for a ship that didn't care to leave the solar system is in place or close to in place.

No it's not. Space is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. The energy needed to reach another star in a reasonable timeframe completely dwarfs the energy needed to reach orbit.

The nearest star, Proxima Centauri, is 4.24 light years away. Say you wanted to travel there within 100 years. Say you can accelerate and decelerate (when you get there) instantaneously (this minimizes trip time and simplifies some of the math). The average velocity you needed for the trip is then 4.24 light years / 100 years = 0.0424c = 12,711 km/sec.

To put something into low earth orbit, you "only" need to reach about 8 km/sec. Energy goes as the square of velocity, so to get a spacecraft to the nearest star within 100 years, you'd need (12711/8)^2 = 2.5 million times as much energy as needed to put the craft into low earth orbit.

The ISS weighs about 450 tons and can support about a half dozen people. Yeah it needs to be resupplied, but ignore that. Say your interstellar spacecraft weighs 1000 tons. To send that to Proxima Centauri in 100 years, you'd need 1.47x10^20 Joules. In terms of nuclear explosions, that's about 35,000 megatons. And that's a minimum. All that energy has to be directed straight back to propel your craft (or straight forward when decelerating). Any of it which goes sideways (like in a nuclear explosion) is wasted, and thus increases your overall energy requirement.

We may be able to get people to another planet within this century. But getting people (or at least their descendants) to other star systems is still centuries away. Barring some technological breakthrough which doesn't violate causality like warp drives do.

RE: Slowly but surly!
By lagomorpha on 12/1/2012 10:36:45 PM , Rating: 3
4.24 light years / 100 years = 0.0424c = 12,711 km/sec.

Fortunately for the crew, at 0.0424c it would only seem like 99.9100716 years due to time dilation. So that saves them almost 33 days which is something...

RE: Slowly but surly!
By eldakka on 12/2/2012 10:12:05 PM , Rating: 2
To put something into low earth orbit, you "only" need to reach about 8 km/sec. Energy goes as the square of velocity, so to get a spacecraft to the nearest star within 100 years, you'd need (12711/8)^2 = 2.5 million times as much energy as needed to put the craft into low earth orbit.

Not quite.

It takes much, much greater energy to escape the planetary well under the influence of gravity than it does to accelerate in deep space.

In climbing to orbit you have to fight against gravity of the earth, which strength reduces proportional to the square of the distance.

So if it takes E energy to accelerate from 0 to 100 at the surface of the earth, then you try the same thing again 1,000,000km away, it would take several orders or magnitude less energy to accomplish the same acceleration.

Using the amount of energy it takes to get to orbit is not a good estimate of how much energy it'd take to accelerate in interplanetary space with reduced gravity effects.

RE: Slowly but surly!
By Calin on 12/3/2012 4:02:52 AM , Rating: 3
Just for your information, speed needed to reach orbit is about 8 kilometers a second, speed to escape Earth gravity well is about 11.2 km/s. To escape Sun's gravity (starting from Earth) you need about 42 km/s.
Compared with the 12,000 km/s you need to reach another star, the 42 km/s to escape Sun's gravity is nothing. Compared to the several successful jumps "out of the Earth gravity well with a human crew" (the voyages to the Moon), it's about four times as much speed, or 16 times as much energy.
As for actually escaping Sun's gravity well, we only have two spacecrafts that did it, the Voyagers (at 15 and 18 billion kilometers). They were launched 35 years ago, and at the target speed of 12,000 km/s needed to reach another star, they have traveled about a million seconds of the 100 years, or 12 days out of a century, or if you want, half of one thousandth part.

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