This artist's rendering shows two Saturn-size planets discovered by NASA's Kepler telescope. Scientists say there is evidence of a third planet, a much smaller one, whose diameter appears to be about 50 percent larger than Earth's. NASA hide caption

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Astronauts will spacewalk on Wednesday in an attempt to fix a broken cooling pump aboard the International Space Station. Though a second pump is currently working, NASA officials are worried about the possibility of it shutting down before the broken pump is fixed. NASA hide caption

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Sound Asleep: NASA's Mars rover Spirit, seen here in an artist's rendering, has been hibernating through the the cold and dark Martian winter, and mission scientists aren't sure when its solar panels will have charged the batteries enough for it to wake up. NASA hide caption

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Ring It In: A trip toward Saturn is just one of many space missions scientists might choose to pursue in the coming years. Some researchers want to send a nuclear-powered boat to the methane lakes on one of Saturn's moons, Titan. Cassini Imaging Team/JPL/NASA hide caption

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