Concept art of InSight Lander drilling beneath Mars' surface.

WASHINGTON — A small lander that will study the geological composition of Mars beat out a comet-hopping probe and a vessel designed to sail the hydrocarbon seas of Saturn’s moon Titan to become NASA’s 12th Discovery-class mission, the space agency announced Aug. 20.

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Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...