The International Space Station as seen from the space shuttle Atlantis after it undocked from the outpost in November 2009. Despite an end to the space shuttle program, NASA says scientific work is just getting into full gear on the space station. NASA hide caption

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The Virgin Galactic VSS Enterprise spacecraft is seen before its first public landing during the Spaceport America runway dedication ceremony near Las Cruces, N.M., on Oct. 22. Virgin Galactic is one of a handful of private companies that plan to fly paying customers into space. Mark Ralston/AFP/Getty Images hide caption

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Mighty Mouse? Male Alston's mice use high-frequency songs to entice females. Bret Pasch/University of Florida hide caption

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By juicing up special cardiac stem cells, researchers hope to find a way for human hearts to heal when they're injured by a heart attack. PRNewsFoto/Zygote Media Group, Inc. via AP hide caption

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An artist's depiction of NASA's Spirit rover on the surface of Mars. Spirit became unresponsive in March 2010. NASA announced it had ended attempts to communicate with the rover on May 24, 2011. NASA hide caption

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Jody Banks displays a selaginella plant at her desk at Purdue University. Banks says selaginella represents an important step in the evolution of plants and produces secondary metabolites that could have medical applications. Andy Jessop/The Purdue Exponent hide caption

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An ash plume rises from the Icelandic volcano Eyjafjallajokull on April 14, 2010. Arni Saeberg hide caption

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Charles Lotter is an operator of Tower Bridge in London and can work all night if a bridge lift is required. Sleep experts say that even people who routinely work night shifts will experience times when they get sleepy in the middle of the night. Peter Macdiarmid/Getty Images hide caption

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In November 1940, just months after its completion, a large section of the Tacoma Narrows Bridge crashed into Puget Sound in Tacoma, Wash. The bridge collapsed under high winds — a failure that shocked engineers at the time. AP hide caption

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Stone artifacts dating back 15,500 years suggest humans may have arrived 2,000 years earlier than previously thought. Courtesy of Michael R. Waters hide caption

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