NASA's Mars helicopter attached to Mars 2020 rover

Engineers attached NASA's Mars Helicopter, which will be the first aircraft to fly on another planet, to the belly of the Mars 2020 rover today in the High Bay 1 clean room at the Jet Propulsion Laboratory in Pasadena, California.

How human networks drive inequality, social immobility

To understand why people succeed or fail, look at their circle of friends. Like it or not, said Stanford economist Matthew Jackson, people's fates are closely connected to their human networks.

Image: 115 years of flight

For most of human history, we mere mortals have dreamt of taking to the skies—from the myth of Icarus, to kites in China, to the development of hydrogen-filled balloons in the 8th century, to early experiments with gliders ...

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