The last remaining space shuttle external propellant tank is moved across the 405 freeway in Los Angeles on Saturday. The ET-94 will be displayed with the retired space shuttle Endeavour at the California Science Center. Chris Carlson/AP hide caption

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This artist's concept depicts some of the planetary discoveries made by NASA's Kepler Space Telescope. Tuesday's announcement more than doubles the number of verified planets discovered by the Kepler mission. W. Stenzel/NASA hide caption

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NASA Spots 1,284 New Planets, Including 9 That Are 'Potentially Habitable'
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An artist's rendering of the BEAM inflatable annex attached to the side of the International Space Station. Courtesy of Bigelow Aerospace hide caption

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NASA To Test Inflatable Room For Astronauts In Space
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Bob Ebeling with his daughter Kathy (center) and his wife, Darlene. Howard Berkes/NPR hide caption

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Challenger Engineer Who Warned Of Shuttle Disaster Dies
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A Martian gravity map shows the Tharsis volcanoes and surrounding flexure. The white areas in the center are higher-gravity regions produced by the massive Tharsis volcanoes, and the surrounding blue areas are lower-gravity regions that may be cracks in the crust (lithosphere). MIT/UMBC-CRESST/GSFC via NASA hide caption

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NASA has set a new launch opportunity, beginning May 5, 2018, for the InSight mission to Mars. This artist's concept depicts the InSight lander on Mars after the lander's robotic arm has deployed a seismometer and a heat probe directly onto the ground. NASA/JPL-Caltech hide caption

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Expedition 43 NASA astronaut Scott Kelly (left) and his identical twin, Mark Kelly, pose for a photograph in 2015 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Bill Ingalls/NASA/Getty Images hide caption

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'Everybody Stretches' Without Gravity: Mark Kelly Talks About NASA's Twins Study
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