The International Space Station has now traveled 2.6 billion miles during its more than 100,000 orbits. That's nearly far enough to reach Neptune, the outermost planet. But since retiring the space shuttle in 2011, Americans have paid Russia's space agency Roscosmos billions of dollars for rides into orbit. NASA Administrator Charles Bolden had hoped to end that dependence in 2017-two years later than planned - with private company SpaceX taking its first astronauts to the ISS, followed by Boeing the year after.
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