National Aeronautics and Space Administration Authorization Act of 2018 This bill reauthorizes the National Aeronautics and Space Administration (NASA) through FY2019. The bill authorizes NASA programs, activities, and reports, including those regarding the International Space Station (ISS); launch, crew, and cargo vehicle critical path redundancy; space suits; earth observation; land remote sensing data collection; Landsat systems; the Goddard Institute for Space Studies; in-space nuclear fission power; civil supersonic transportation research; unmanned aircraft systems research; commercially provided space products and services; commercial in-space infrastructure; and NASA-funded institutes. NASA shall: continue the operation of the ISS; establish a research office at the Johnson Space Center to build upon its expertise in human space flight missions for future challenges; partner with private sector and philanthropic organizations to search for technosignatures, such as radio transmissions, in the search for life's origin and future in the universe; establish the 21st Century Aeronautics Research Capabilities Initiative; more effectively and efficiently share its electromagnetic spectrum with U.S. nongovernmental entities operating or proposing to operate space objects; and restrict contracting with contractors who have a history of poor performance on space contracts. The bill extends NASA's authority to lease nonexcess properties through 2020. The National Space Council shall publish a report that relates the strategic national importance of space to the inherent risk of exploring and using it.