WASHINGTON — An engineering model of a NASA instrument scheduled to fly to space aboard the Japanese Astro-H X-ray observatory in 2014 malfunctioned during testing in Japan, raising the possibility of further delays for a mission whose launch has already been pushed to the right by natural disasters.

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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...