National Aeronautics and Space Administration Authorization Act of 2019 This bill reauthorizes the National Aeronautics and Space Administration (NASA) for FY2021. The bill provides for continued use of the International Space Station through 2030 and authorizes NASA programs and activities, including a rocket engine test infrastructure program, a low-Earth orbit commercialization program, a Lunar Discovery Program for lunar science research, a 21st Century Aeronautics Capabilities Initiative, a Skilled Technical Education Outreach Program for secondary school students, and a 21st Century Space Launch Infrastructure Program. NASA shall establish the Planetary Defense Coordination Office to implement a program for surveying threats posed by near-Earth objects equal to or greater than 140 meters in diameter. NASA shall also continue providing opportunities for formal and informal STEM (science, technology, engineering, and mathematics, including computer science) education engagement activities, including under the Established Program to Stimulate Competitive Research (EPSCoR).