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Mercury is getting its first man-made visitor in more than 30 years. NASA’s Messenger space probe is heading for a rendezvous with the planet, where sunlight is 11 times as bright as here on Earth and temperatures can swing from a metal-­melting 450 C in the sunlight to lows of �180 C in the shade.

In the first of several encounters, Messenger (an acronym for MErcury Surface, Space ENvironment, GEochemistry, and Ranging ) is scheduled to fly by Mercury on 14 January 2008 at a little more than 25 000 kilometers per hour, ­coming within 200 km of the planet’s surface. Because it must perform scientific observations and relay them to Earth while in the scorching glare of Mercury’s tight solar orbit, the craft boasts a multi­layer sunshade and the most advanced communications systems ever deployed in an interplanetary mission.

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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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