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Killer Electrons From Outer Space

Accurate space-weather forecasts could come from knowing the cause of superfast electrons in the Van Allen belts

4 min read

31 August 2007—Researchers at Los Alamos National Laboratory, in New Mexico, say they have solved the mystery of satellite-zapping ”killer electrons” that are sometimes produced in Earth’s outer atmosphere. These highly energetic electrons—strong enough to damage electronics and human tissue—pose a danger to spacecraft, satellites, and astronauts. For many years, the mechanism by which they are produced has remained little understood, in spite of physicists’ attempts at solving this puzzle.

Now, Yue Chen, Geoffrey Reeves, and Reiner Friedel say they have conclusively proved that killer electrons come about because very-low-frequency electromagnetic waves—themselves of somewhat mysterious origin—accelerate ordinary electrons in the Van Allen radiation belts to a point where they are traveling at velocities close to the speed of light. The three scientists published their results in the July 2007 issue of the journal Nature Physics .

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Economics Drives Ray-Gun Resurgence

Laser weapons, cheaper by the shot, should work well against drones and cruise missiles

4 min read
In an artist’s rendering, a truck is shown with five sets of wheels—two sets for the cab, the rest for the trailer—and a box on the top of the trailer, from which a red ray is projected on an angle, upward, ending in the silhouette of an airplane, which is being destroyed

Lockheed Martin's laser packs up to 300 kilowatts—enough to fry a drone or a plane.

Lockheed Martin

The technical challenge of missile defense has been compared with that of hitting a bullet with a bullet. Then there is the still tougher economic challenge of using an expensive interceptor to kill a cheaper target—like hitting a lead bullet with a golden one.

Maybe trouble and money could be saved by shooting down such targets with a laser. Once the system was designed, built, and paid for, the cost per shot would be low. Such considerations led planners at the Pentagon to seek a solution from Lockheed Martin, which has just delivered a 300-kilowatt laser to the U.S. Army. The new weapon combines the output of a large bundle of fiber lasers of varying frequencies to form a single beam of white light. This laser has been undergoing tests in the lab, and it should see its first field trials sometime in 2023. General Atomics, a military contractor in San Diego, is also developing a laser of this power for the Army based on what’s known as the distributed-gain design, which has a single aperture.

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