WASHINGTON — An astronaut told U.S. lawmakers July 25 that the greatest impediment to research and science aboard the international space station (ISS) is the limited amount of time crew members can devote to these pursuits.

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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...