SAN FRANCISCO — NASA’s dwindling corps of astronauts may not be large enough to staff the international space station, support the development of commercial crew vehicles and help space agency officials draft plans for future exploration missions beyond low Earth orbit.

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Debra Werner is a correspondent for SpaceNews based in San Francisco. Debra earned a bachelor’s degree in communications from the University of California, Berkeley, and a master’s degree in Journalism from Northwestern University. She is a recipient...