U.S. Leadership in Space Act of 2019 This bill sets forth programs, projects, and activities regarding human exploration of space. The bill authorizes the National Aeronautics and Space Administration (NASA) to conduct missions to intermediate destinations, such as the Moon, if each such mission demonstrates or advances a technology or operational concept that will enable human missions to Mars. NASA shall establish the Artemis program management office at the Lyndon B. Johnson Space Center in Houston, Texas. The Artemis program is the NASA program for going back to the Moon and for establishing sustainable exploration there. NASA shall establish a plan for the development and manufacture of advanced spacesuits; may carry out a program to conduct lunar science research, including missions to the surface of the Moon; shall ensure that the International Space Station (ISS) remains a viable and productive facility of potential U.S. use through at least FY2030; shall establish a low-Earth orbit development program to encourage commercial use and development of space by private entities in the United States; must update and improve the cybersecurity of its space assets and supporting infrastructure; and must maintain a Security Operations Center to identify and respond to cybersecurity threats to its information technology systems. The bill extends through 2030 authorization for cash or in-kind payments by the United States to Russia for certain work or services regarding the ISS.