National Aeronautics and Space Administration Authorization Act of 2018 This bill reauthorizes the National Aeronautics and Space Administration (NASA) for FY2019, provides for the continuation of the International Space Station, and authorizes NASA programs and activities, including a low-Earth orbit commercialization program, a lunar discovery program, an unmanned aircraft systems operation program, a 21st Century Aeronautics Research Capabilities Initiative, and a small satellite launch services program.