IOTD stories

 
You won't get much thrust out of an ion thruster: compared to a chemical rocket engine, they're not all that impressive. What makes ion thrusters so great is their ability to put out small amounts of thrust very efficiently and for a very long time, and NASA's Evolutionary Xenon Thruster has now been operating for 43,000 hours. That's nearly five years straight.
 
Andrew Choy took this night shot of San Francisco International Airport from a Cessna back in 2005. Gorgeous, right? It was even a finalist for the 2006 Wikimedia Commons Picture of the Year. With all that hectic holiday travel underway, it's nice to see such beautiful shot of one of the busiest airports in the United States.

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