Science

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This is the moon as Morse code.

"I grew up wanting to fly," says Graham Bowen-Davies. "I guess I just settled for being an engineer."

He's standing on an indoor track in southern Maryland, watching a giant helicopter take flight. At the end of each of its four spindly arms — arms he helped design and build — a giant rotor churns the air. In the cockpit sits the engine: a 0.7-horsepower, 135-pound graduate student named Kyle Gluesenkamp.

Gluesenkamp is pedaling like crazy to keep the rotors spinning and the craft aloft.

Few things are as rare as a piece of rock that falls from outer space and crashes onto Earth.

Among the most prized of these meteorites are from Mars. Friday, scientists describe the latest one discovered: It's called Tissint, and this weekend you can buy a piece of it.